JP3061802B2 - Optical disc, optical disc apparatus, and optical disc tracking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a format of a recognition pattern for recognizing a header portion provided at the head of an information sector of an optical disc to be recorded on both lands and grooves of the optical disc, and an optical disc apparatus for reproducing the optical disc. , And an optical disk tracking method.

[0002]

2. Description of the Related Art Existing phase-change optical disks record data only in grooves called grooves. Land plays a role in guiding during tracking and suppressing crosstalk from the adjacent groove track. If data is recorded on the land, the track density can be doubled while the groove width remains the same. However, it was thought that the recording density would not increase so much even if land / groove recording was used because crosstalk would increase. However, if the step between the groove and the land was set to about λ / 6 (λ is the wavelength of the light source), It can be seen that crosstalk between adjacent tracks can be suppressed, and there has been a history of land / groove recording to increase the density. In particular, there is an advantage that the mastering of the disk is facilitated as compared with the case where the track pitch is narrowed without using the land / groove recording.

An optical disk for performing land / groove recording has a concentric configuration. When recording is performed for one round of the disk, a track jump is performed, and an adjacent track (for example, if a groove track is present, an adjacent land track is used). ) Start writing. In this case, since each sector is always managed by a sector address, for applications where only discontinuous data such as computer data is recorded and reproduced,
Operation can be performed without any trouble using a buffer memory or the like.

[0004] However, rewritable optical discs may handle continuous data such as moving pictures and music in addition to those for computers. In particular, in multimedia applications (applications in which data and video / audio are mixed), it is conceivable to use the same spiral track as a CD so that continuous data can be easily handled.

[0005] In this case, there is a case where the track is formed in a spiral shape so that continuous writing can be performed without using concentric tracks as in an existing magneto-optical disk. However, if the disk is recorded in both lands and grooves in a spiral configuration, only the grooves or lands are traced from the start of the track to the end, and when either one has been recorded or reproduced, the lands and grooves are recorded. You need to switch and record again. However, in this case, when switching between the land and the groove, access from the inner circumference to the outer circumference of the disk is required, and there is a problem that it takes time. For example, in a disk in which this operation is divided into several zones in the radial direction of the disk, even if switching between lands and grooves is performed in units of zones, recording or reproduction must be suspended for a considerable time during access.

FIG. 23 is a diagram showing details of a header section of a conventional land / groove recording disk.
3 (a) shows a case where a header is formed on both the land track 2 and the groove track 1, and FIG. 23 (b) shows a case where a header is formed at the boundary between the land 2 and the groove 1. Reference numeral 4 denotes a header.

[0007] The header portion is an uneven portion physically formed to represent address information of a sector, which is a unit for recording data, and the like. Specifically, a pit having the same height as a land or a pit having the same depth as a groove is formed in a header portion having no track. There are several methods for forming prepits suitable for land / groove. Among them, the main method is a method having a dedicated address as shown in FIG. 23A for each track unit, and FIG. As shown, there are two schemes having an intermediate (shared) address.

In the dedicated address system, dedicated pre-pits are provided for each sector of a land and a groove. Since a lot of information such as whether the sector is a land or a groove can be included, the control on the optical disk device becomes easy. However, the width of the pit needs to be sufficiently smaller than the track width. That is, prepits cannot be formed with the same laser beam as that used to form tracks, and the structure of the medium becomes difficult.

On the other hand, the intermediate address method is a method in which adjacent lands and grooves share prepits. The pits can be formed by shifting the position in the radial direction by １ ／ of the track width using the same laser beam as that used to form the track. However, it is necessary for the optical disk control side to determine whether it is a land or a groove, and the control becomes complicated.

[0010] In the optical disk for recording and reproducing data as described above, it is necessary to solve the problem of the occurrence of track offset in addition to the configuration of lands and grooves for increasing the recording density. This is because the optical disk for recording requires a large laser power, and is not a method of splitting a beam by a three-beam method or the like.
This is because a method of performing tracking with one beam such as a push-pull method was required. Also, in perforated recording of a write-once disc or the like, there is a problem that a tracking operation is disturbed because side spots for tracing tracks after recording become disturbances.

[0011] Push-pull tracking is a method of forming a servo system by detecting a tracking error using the diffraction distribution of a light spot irradiated on a pregroove as shown in FIG. There is a problem that offset occurs due to the above. In FIG. 24, 6
6 is a laser diode, 65 is a half mirror, 67 is an objective lens, 64 is an actuator coil for driving the objective lens, and 9 is a disk motor. For example, a tilt of 0.7 ° or an eccentricity of 100 μm (FIG. 24)
(Equivalent to 100 μm translation of the objective lens 62 indicated by a dotted line therein), and the light distribution 12 on the photodetector 11 shifts, resulting in an offset of about 0.1 μm.

In order to prevent such a phenomenon, various devices have been devised, such as a mechanically and optically highly accurate driving device. In a reproduction-only system such as a CD, 3
Although techniques such as the spot method have been established, this method is not suitable for a recording / recording / reproducing system.

Therefore, conventionally, 1 /
A wobble pit method for preparing pits shifted by two pitches is known. FIG. 25 (a) is “Optical Memory Symposium '85”, p18 of the Optoelectronic Industry and Technology Advancement Association.
FIGS. 1 to 188 are diagrams showing mirror surface correction methods described in “Composite Track Wobbling Optical Disk Memory” and p209 to p214 “Study of Track Offset Correction Method”, and FIG. 25B is used for a correction method using a wobbling pit. FIG. 3 is a diagram illustrating a pit configuration of an optical disc. In the figure, 7 is a mirror surface portion, and 68 and 69 are wobbling pits.

FIG. 26 is a block diagram showing a conventional track offset correction circuit using the mirror portion 7. Numeral 70 denotes a track error detecting circuit for detecting a track error by the push-pull method.
A split detector, 16 is a differential amplifier for obtaining a track error from the two-split detector 70, 20 is a mirror detector for obtaining the detection timing of the mirror 7, and 23 is a track when the light spot passes through the mirror. A sample and hold circuit 47 for holding the error signal, and a differential amplifier 47 for obtaining a difference between the offset information from the sample and hold circuit 23 and the track error signal.

FIG. 27 is a block diagram showing a conventional offset correction circuit using wobbling pits 68 and 69. Reference numeral 22 denotes a wobble pit detection circuit for obtaining wobble pit detection timing, and reference numerals 23 and 24 denote wobble pits 68 and 69. A sample and hold circuit for holding the amount of reflected light obtained when the light spot passes through 69;
Reference numeral 27 denotes a differential amplifier for obtaining a difference between the outputs of the sample and hold circuits 23 and 24, and reference numeral 28 denotes an addition for adding the track error signal obtained by the differential amplifier 27 to a track error signal by a normal push-pull method. Circuit.

FIG. 28 is a diagram showing control characteristics when a track error signal obtained by wobble pits and a track error signal by a normal push-pull method are used at the same time. G2 is a tracking open loop characteristic by a wobble pit, and G2 is a tracking open loop characteristic by a pull method.

In the case of the conventional mirror surface offset correction shown in FIG. 25A, a mirror surface portion 7 is provided by cutting a part of the guide groove. In this case, a correction circuit for mirror offset correction as shown in FIG. 26 is required. Two signals received by the two-segment photodetector 70 are input to the differential amplifier 16 to become a tracking signal, and one sum signal becomes an information signal and is guided to the mirror detector 20 to sample the signal level. For generating a timing signal. Tracking signal ΔT obtained by differential amplifier 16
Includes the error ΔTg, the true track error ΔTs, and the track offset δ due to the disk tilt, etc., so that ΔT = ΔTs + ΔTg + δ... The sample and hold circuit 23 holds the tracking signal of the mirror unit 7 for each sector, and outputs △ Tg + δ of the tracking signal △ T. Therefore, if the output of the sample-and-hold circuit 23 is corrected by the differential amplifier 47 according to the equation 1, a tracking signal of only ΔTs is formed to form a closed-loop servo system, and accurate track tracking is performed.

In addition to the above-described method of mirror surface correction,
There is a correction method using a wobble pit described below. As shown in FIG. 25 (b), this method can be performed by forming a pair of pits distributed to the left and right from the center of the track using an ultrasonic optical deflector at the time of forming the master. At the time of recording / reproducing, a track error is detected by comparing the magnitude relationship of the reflected light when the light spot has passed, and the output difference between the sample and hold circuits 23 and 24 shown in FIG. By the differential amplifier 27.

In this case, as shown in FIG. 29, when the wobble pit is used, that is, when the light spot passes through the upper pit 68, an output signal as shown by a dotted line is obtained. When the signal passes through the closer one, an output signal with the phase inverted by 180 ° as shown by the solid line is obtained, and the value obtained by subtracting the signal value of the following pit from the signal value of the preceding pit indicates the magnitude and direction of the track shift amount. Becomes This means that the true light spot passage position can be detected, and a more advanced servo system can be configured as compared with the system using only the diffraction distribution by the pre-groove.

Further, a tracking method has been devised which maintains the characteristics of the wobble pit method as described above and maintains perfect compatibility with a system using a push-pull tracking which is a general conventional method. ing. The sector configuration of this system is divided into an index field in which pits are formed in advance as shown in FIG. 23B and a data field to be used later by the user. Further, in the index field, wobble pits are newly provided together with address information and the like, or are arranged also as sector detection marks, and at the same time, a tracking pre-groove is also formed.

With such a sector configuration, it is possible to detect a true track deviation amount in wobble pits, and to correct an offset in push-pull tracking. In this case, as shown in FIG. 28, in the open loop characteristic of the tracking servo, the tracking gain by the wobble pit is increased in the low frequency region, and the tracking gain by the push-pull method is increased in the high frequency region. As a result, no matter which drive device is used, data can be recorded / reproduced while always keeping the light spot at the center of the track, and it is possible to prevent a situation in which compatibility between the recorded disk and the drive device is poor.

[0022]

In the above-mentioned conventional optical disk apparatus, information has been recorded on both lands and grooves in order to improve the recording density. However, in such an optical disk, in order to avoid the complexity at the time of disk mastering, the information track is shifted from the information track by a half pitch in the disk radial direction so that the information can be read from either the land or the groove. It was necessary to provide an address pit string in the header. For this reason, as a result, one header is shared by the land and the groove, and it is difficult to determine whether the land is currently being scanned or the groove is being scanned simply by reading the address. In the case of a spiral disk having a configuration in which a land and a groove are continuous every other rotation, it is necessary to determine whether the next sector is a land or a groove. In particular, if this determination is incorrect, the servo will be deviated, so that it is necessary to reliably detect the land / groove polarity.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is an optical disk capable of recording data on both lands and grooves, in which the polarity inversion can be determined from the recognition pattern of the subheader. It is another object of the present invention to obtain an optical disk device for the optical disk and a tracking method for the optical disk.

[0024]

In an optical disk according to the present invention, a continuous information track is formed in a switching portion appearing every other rotation while a land track and a groove track are switched, and this information track is formed in a radial direction. An optical disc divided into a plurality of zones according to the position of the information recording track, the information recording track is divided into a plurality of sectors each having an information recording unit length in the scanning direction, and a sub-header portion is provided at a leading portion of each sector. A plurality of sub-headers are arranged with a shift of about 1/2 pitch in the radial direction with respect to the scanning direction of the information recording track, and a recognition pattern for obtaining the polarity inversion timing of the information recording / reproducing portion of the sector is provided in the sub-header. It is characterized by being arranged.

Further, a continuous information track is formed at the switching portion appearing every other rotation while the land track and the groove track are switched, and this information track is divided into a plurality of zones according to the position in the radial direction. An optical disc, wherein the information recording track is divided into a plurality of sectors each having an information recording unit length in the scanning direction, and a subheader is provided at the head of each sector, and the subheader is arranged in the scanning direction of the information recording track. A plurality of discs are shifted by about 1/2 pitch in the front and rear in the radial direction, and a recognition pattern for obtaining the timing of reversing the polarity of the information recording / reproducing portion of the sector is track-accessed to the optical disc arranged in the sub-header section. Recognize the above recognition pattern from the output signal, and based on the recognition result, a tracking error signal Wherein the optical tracking method of switching the polarity.

Further, at the switching portion appearing every other rotation, one continuous information track is formed while the land track and the groove track are switched, and this information track is divided into a plurality of zones according to the position in the radial direction. An optical disc, wherein the information recording track is divided into a plurality of sectors each having an information recording unit length in the scanning direction, and a subheader is provided at the head of each sector, and the subheader is arranged in the scanning direction of the information recording track. When the information is read from an optical disk device using an optical disk in which a recognition pattern for obtaining the timing of the polarity inversion of the information recording / reproducing portion of the sector is arranged in the subheader portion, the plural patterns are arranged shifted by about 1/2 pitch in the radial direction. Reproducing means for reproducing a reproduced signal, and recognizing a recognition pattern from the reproduced signal reproduced by the reproducing means. Recognizing means for, characterized by an optical disk apparatus having a switching means for switching the polarity of the tracking error signal based on the result of said recognition means.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an optical disk according to the present invention, a plurality of sub-headers including a recognition pattern and an address number constituting a header are shifted from the scanning direction of an information track back and forth by 1/2 pitch. By arranging, track offset and polarity inversion are detected.

Further, the optical disk apparatus and the optical disk tracking method according to the present invention enable the polarity inversion to be determined based on the information obtained from the recognition pattern not only during information recording / reproduction, but also during access.

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. Embodiment 1 FIG. FIG. 1 is a diagram showing an optical disc according to Embodiment 1 of the present invention.
FIG. 1A shows a sector arrangement of an optical disk in which a land and a groove form a continuous spiral, wherein 1 is a groove, 2 is a land, and 3 is a header formed at the head of the sector. . FIG. 1B shows a sector arrangement of an optical disk in which a land and a groove are continuous every other rotation, and reference numeral 4 denotes a header portion of a sector where the land and the groove are switched.

FIG. 2 is a diagram showing a zone configuration of the optical disk according to the first embodiment. In the drawing, the zones are divided into three zones A, B and C for simplification.

FIG. 3 is a configuration diagram showing a header portion of a sector which is a unit for recording and reproducing information on the optical disk according to the first embodiment of the present invention. FIG. 3A is a schematic diagram showing a pit arrangement. FIG. 3B is a schematic diagram showing the recording data arrangement inside the header. In FIG. 3, reference numeral 5 denotes a subheader describing addresses A to D, 6 denotes a header composed of a plurality of subheaders, and 7 denotes a mirror portion for detecting a track offset.

FIG. 4 shows that the offset caused by the polarity inversion in the first embodiment is corrected by the mirror surface detection method.
A diagram showing a method of correcting the sensor offset generated in a normal push-pull method by wobble pits,
8 is an optical disk, 9 is a disk motor, 10 is an optical head, 11 is a two-divided photodetector, 12 is a light amount distribution of a light spot incident on the photodetector 11, and 13 is a photocurrent at the photodetector 11 as a voltage. IV amplifier for conversion, 14
Is a polarity inversion circuit, 15 is an addition amplifier for detecting the amount of reflected light from the disk, 16 is an addition amplifier for generating a tracking error signal, 17 is a PLL and data detection circuit for extracting data, and 18 is a wobble pit. A pattern matching circuit capable of performing pattern matching including; 19, a polarity inversion position detection circuit for determining whether to perform polarity inversion; 20, a mirror surface detector for generating detection timing of the mirror surface portion 7; A wobble pit detection circuit for obtaining a detection timing.
A sample-and-hold circuit for holding a sum signal, which is the amount of reflected light, when a light spot passes through two wobble pits; 26, an addition amplifier for adding a correction value obtained by mirror detection to the original tracking error signal;
Is a differential amplifier for operating the sample and hold circuits 24 and 25, and 28 is an adder for adding the tracking error signal generated by the wobble pit to the original tracking error signal.

FIG. 5 is a diagram showing a pit configuration of a header portion of the optical disc according to the first embodiment.
A VFO 30 for facilitating L pull-in and facilitating detection of an address or the like in the header portion, 30 is a recognition pattern for recognizing the header portion, and 31 is address data indicating a sector address.

FIG. 6 is a diagram showing a pit configuration of a plurality of subheaders in the header portion of the optical disk according to the first embodiment.

FIG. 7 shows an example of the configuration of the recognition pattern 30 in the header portion of the optical disc according to the first embodiment. In the drawing, A, B, and C are examples of different recognition patterns.

FIG. 8 is a diagram showing the VFO 29, the recognition pattern, and the scanning trajectory of the light spot at the time of track access in the header portion of the optical disk according to the first embodiment.

FIG. 9 is a diagram showing an example of the configuration of a subheader in the header section of the optical disc according to the first embodiment.

FIG. 10 is a diagram showing the configuration of the recognition pattern 30 in the sub-header.
33 is an ID describing the order of the matching pattern, etc., 3
Reference numeral 4 denotes a zone determination unit indicating the order of the zone to which the matching pattern 30 belongs, and reference numeral 35 denotes a mirror surface for performing offset correction.

FIG. 11 shows one recognition pattern 30 for example.
It is a figure which shows the example of a structure at the time of being comprised by 4 bytes.

FIG. 12 shows, for example, one recognition pattern 30.
It is a figure which shows the example of a structure at the time of being comprised by 3 bytes.

FIG. 13 shows one recognition pattern 30 for example.
It is a figure which shows the example of a structure at the time of being comprised by 2 bytes.

General land / groove disk (optical disk for recording data in both land and groove)
Is formed in a spiral shape as shown in FIG. In this case, the land track 2 is connected to the land track 2 even after making one round. The same applies to groove track 1. Therefore, two spirals, a spiral with only lands and a spiral with only grooves, are formed. On the other hand, in an optical disk on which continuous information tracks need to be formed, as shown in FIG. 1 (a), the track 2 of the land changes to the track 1 of the groove and the track 1 of the groove changes to the land 1 every round. To track 2 One spiral in which the land and the track are switched for each lap.

In the optical disk shown in FIG. 1B, data is recorded on one spiral track like a CD, and there is an advantage that a track jump method may be the same as that of a CD. Conventional spiral optical discs must incorporate a special track jump method, such as moving the optical head to the beginning of the groove track after scanning all land tracks, so the recording speed suddenly drops in such places On the other hand, when a track is formed by a mastering device, a simple spiral may be drawn.

On the other hand, in the optical disk shown in FIG. 1B, it is necessary to shift the position to be irradiated with the laser beam by the track pitch in the radial direction for each round. However, the most problematic point is that it is necessary to switch the tracking polarity between the land and the groove every round in the optical disk of FIG. In particular, the reverse of the offset, which occurs when the polarity is switched, becomes a problem.

In an optical disk for recording and reproduction, CLV rotation is performed in order to keep the number of rotations constant, or the disk is divided into several zones in the radial direction of the disk as shown in FIG. A method has been proposed in which the variation in linear speed is reduced by changing the number of revolutions. In the case of CLV rotation, the header portion of each sector is not aligned in the radial direction as compared with the zone division in FIG. 2, so that crosstalk interference reproduced from prepits in the header portion when recording data on lands and grooves is problematic. Becomes Therefore, a disk having a zone configuration as shown in FIG. 2 is generally used.

Further, as shown in FIG. 3, the configuration of the header portion in each sector is such that different addresses are reproduced for lands and grooves by sub-headers being alternately recorded while being shifted in a 1/2 track pitch radial direction. It is possible to do. On the other hand, in the conventional configuration of the address pits as shown in FIG. 23A, it is necessary to move the cutting machine for manufacturing a disk in units of 1/2 pitch.
In the configuration shown in FIG. 3B, the same address is reproduced in the land and the groove. Therefore, there is a problem that it is impossible to determine whether the light spot is the land reproduction or the groove reproduction only from the reproduction signal.

In the method shown in FIG. 3 according to the first embodiment, the information content of the address pits is configured to be shifted by 1/2 track alternately as shown in FIG. 3 (b). Address determination becomes possible. For example, when playing groove track 1,
The data is reproduced in the order of address A-address B-address A-address B. In the case of the land track 2 adjacent thereto, reproduction is performed in the order of address C-address B-address C-address B. The difference can be determined.

Further, the address pits are alternately arranged as wobbling pits, and the mirror surface portion 7 is also formed. An unnecessary offset of the push-pull sensor method can be removed.

Here, as a method of removing the offset,
Conventionally, there are a mirror surface correction method and a wobble pit correction method that have been proposed. In a general recordable / reproducible optical disc, as a configuration in which a groove is not provided partially,
A header portion of a sector is formed in that portion, and information such as a sector address is written in advance in concave and convex pits. In the case of land / groove recording, if this uneven pit is configured as shown in FIG. 3, the address pit itself can be used as a wobble pit.

However, a particularly problematic point is shown in FIG.
As shown in FIG. 1 (b), in an optical disc in which lands and grooves continue every other track, a header 4 for which the tracking polarity must be switched exists once per rotation as shown in FIG. 1 (b). Here, a more detailed decomposition of the tracking error signal ΔT up to the servo compensation circuit obtained by the push-pull method is as follows. ΔT = ΔTs + ΔTg + δ + ΔTt + ΔTi + ΔTh Equation 2 ΔTs: True tracking error signal ΔTg: Offset generated by objective lens shift δ: Offset generated by disc tilt ΔTt: Light detection ΔTi: Offset from detector to polarity reversal circuit ΔTh: Offset from polarity reversal circuit to servo compensation circuit

The true tracking error signal .DELTA.Ts has the opposite polarity when switching from a groove to a land or from a land to a groove, so that a correct track error signal can be obtained by inverting the signal by a polarity inversion circuit. For this reason, ΔTs is a portion where there is no problem even if the polarity is inverted. However, since the offset ΔTg due to the lens shift and the offset δ due to the disk tilt occur independently of the land and the groove, if the polarity is inverted as it is, an offset in the opposite direction will be applied. It is necessary to correct the amount of ΔTg and δ obtained by the Bling pit and the mirror surface correction method each time the polarity is inverted. Also, in the method using ΔTg estimated from the objective lens position sensor of the optical head or the method of storing ΔTg for one round of the track in the memory before the tracking operation and then correcting the ΔTg, the ΔTg can be reduced even when the polarity is reversed. Correction is performed without inversion.

Since .DELTA.Tt and .DELTA.Ti need only be corrected once before the operation of the apparatus or at the time of shipment from the factory, they are generally corrected together with .DELTA.Th by, for example, offset adjustment of a servo circuit. Often have. However, △ Tt and △ Ti are inverted by the inverting circuit at the time of polarity inversion, whereas △ Th is not inverted, so that offset errors in the opposite direction of △ Tt and △ Ti occur. There is. Therefore, as shown in FIG.
A circuit 23 that samples and holds a tracking error signal when the light spot passes through the mirror surface is provided at a stage subsequent to the polarity inversion circuit 14, and the original tracking error signal is corrected by the differential amplifier 26 using the output of the sample and hold circuit 23. This makes it possible to perform correction including ΔTt and ΔTi.

By providing the sample-and-hold circuit 23 dedicated to polarity inversion as shown in FIG. 4, even if, for example, an address pit or a recognition pattern of a sector with polarity inversion cannot be detected, the previous polarity inversion is performed. Since the offset correction value at the time can be used, disturbance of the servo operation due to the polarity inversion can be prevented. For example, in the case of FIG. 4, the subheader 5 is detected by the PLL and data detection circuit 17 and the pattern matching circuit 18, and the offset caused by the push-pull sensor is corrected by the tracking error signal due to the wobble pit. For sectors with polarity reversal,
The presence / absence of polarity inversion is detected by the polarity inversion position detection circuit 19, the sample / hold circuit 23 is operated at the timing from the mirror surface detector 20, and the offset is corrected by the differential amplifier 26.

Therefore, for example, when the mirror surface detection timing at the time of polarity inversion cannot be obtained due to a scratch on the disk, etc.
Stable operation is compensated for by using the offset value at the time of polarity inversion retained one cycle before and remaining in the sample and hold circuit 23 as it is. In addition, even if the data cannot be detected due to a scratch or the like one cycle before, the value obtained one cycle before can be substituted and the previous history can be used continuously. This is because the polarity reversing sectors are aligned in the radial direction of the disk as shown in FIG. 2, so that the mounting error of the photodetector 11, the offset ΔTt generated by the stray light in the optical head, the polarity from the photodetector 11, Inverting circuit 1
This is because not only the offset ΔTi up to 4 and the offset δ due to the disk tilt but also the rotation angle with respect to the disk eccentricity, the offset ΔTg generated by the objective lens shift has almost the same value. . The correction of the offset at the time of the polarity reversal involves a large amount of change as compared with the correction of the offset in a normal sector, and therefore, the correction is an essential operation.

The system having a dedicated correction circuit at the time of polarity reversal using mirror surface detection is operated in combination with the correction by wobble pits as shown in FIG. In this case, the tracking error signal from the wobble pit is generated by the differential amplifier 27 and added to the original tracking error signal, thereby performing the tracking operation with the wobble pit having no offset in the low frequency region as shown in FIG. Even in this case, since the offset correction amount at the time of polarity inversion has a larger change than the correction amount in a normal sector, only the offset by the mirror surface is extracted and the correction is performed by feedforward. Therefore, the correction loop based on the wobble pit does not require a sudden change even when the polarity is inverted, and is a smooth change that can be sufficiently corrected by the control loop G2 in FIG.

In the above-described correction operation, a pattern matching signal is generated from the reproduction address data 31 by reproducing the address pits in the subheader 5 shown in FIG. 5, and the polarity inversion circuit 14 is first inverted with this signal. The tracking error signal at the time of passing through the mirror surface is held by the pattern matching signal and the generated sample hold timing signal. Such an offset correction operation naturally involves no polarity inversion of the tracking error signal.
This is also performed on a disc as shown in FIG. This is because the push-pull tracking error detection method is offset by a lens shift or the like. In the offset correction operation and the polarity inversion operation described above, when a malfunction occurs, the servo is deviated and the like, which hinders the reproduction operation of the entire sector.

Therefore, in the header section, as shown in FIG. 5, the recognition pattern 30 is formed by a pit row longer in the disk line direction than the normal address pits. A pattern that is not used in the modulation method in is used. This makes it easy to distinguish between the normal data and the recognition data, and simplifies the configuration of the pattern matching circuit.

In recent years, a modulation method for recording and reproducing information sometimes uses a block code. For example, in this case, a ROM table for converting 8-bit data to 16 bits is prepared. For example, a combination in which the minimum / maximum inversion interval satisfies a predetermined value and the fluctuation of DSV (Digital Sum Value) is reduced. By selecting and recording in the ROM, encoding becomes possible. The decoding operation can be performed by performing the above operation in reverse. In the case of such a block modulation method, there is a combination of patterns that are not included in the modulation pattern. Therefore, if this pattern is used as the recognition pattern 30, when the recognition pattern 30 is subjected to pattern matching, it is separated from other information recording data. It is possible to do. In addition, by using a pit string that is long in the disk line direction (for example, the shortest pit length is longer than that used in the information recording portion), it is possible to reduce the error rate when the recognition flag is detected.

In these recognition patterns 30,
If a different pattern is described for each zone as shown in FIG. 7, it is possible to determine to which zone the currently scanned light spot belongs, thereby controlling the rotation of the disk motor 9. It can be done reliably.
For example, if the rotation of the optical disk on which recording is performed is incorrect, especially on a medium having a strong linear velocity dependence such as a phase change disk, the recording characteristics do not match in the relationship between the laser power and the linear velocity, and information such as overwrite operation is not obtained. May not be recorded properly. Therefore, the determination of the zone must be performed more reliably. In the case of FIG. 7, three cases of A, B, and C are shown. However, in actuality, any method may be used. For example, a method of preparing recognition patterns 30 that differ by the number of zones on the disk is the simplest. When the number of combinations of the recognition patterns is smaller than the number of zones, for example, a method of repeating A, B, C, A, B, and C can cover to some extent. This is because, if the number of rotations in the past zone is known, it can be determined from the number of changes in the recognition pattern based on the number of rotations.

Further, as shown in FIG. 10, if the ID number is described in the recognition pattern 30, the detection reliability of the recognition pattern 30 is further improved. For example, in the case where a plurality of recognition patterns 30 exist in one subheader 5 as shown in FIG. 6, or in the case where a plurality of subheaders 5 themselves exist as shown in FIG.
By reading this ID, the location of the recognition pattern 30 in the header section 6 can be determined, whereby the wobble pit detection timing and the mirror surface section 35 in FIG.
In addition to the detection timing of the mirror portion 7 in FIG.

Further, by comparing the IDs 33 in a plurality of reproduced recognition patterns, it is possible to reconfirm whether the reproduced data is the recognition pattern 30 or not, thereby improving the reliability of the recognition pattern 30. For example, if it is determined whether or not the reproduced IDs 33 are sequentially incremented, it is possible to determine that the recognition pattern 30 having the ID 33 that has not been incremented is an incorrect pattern.

Further, in these recognition patterns 30, unlike the case shown in FIG. 7, as shown in FIGS. 11 to 13, a pit dedicated for matching, an ID 33, a zone determination section 34, a mirror section 35, and the like are provided. It is possible to have
By these combinations, for example, the 4-byte configuration is changed to
It can be realized by a YTE configuration or the like. The mirror portion 35 shown in FIGS. 10 and 11 indicates the start and end of a plurality of matching patterns in addition to the removal of the track offset. The mirror portion 35 also forms a part of the matching pattern. I have.

As described above, the above-described recognition pattern 30
As a matter of course, the data detection is easier than the normal reproduction data and the address information in the header section 6. In addition, because the configuration has been made to increase the reliability,
It is possible to surely provide necessary information at the time of land / groove recording, thereby enabling tracking operation and rotation control without error.

Embodiment 2 The above-described zone recognition and land / groove recognition can also be performed by reading the contents of the address data. For example, by reading the address of the disk, the zone is divided into predetermined zones in a certain radial direction, and if the number of sectors per round in each zone is constant, the polarity inversion is performed by the arrangement of the sector numbers in the zone. Presence or absence can be detected. For example, assuming that the number of sectors per round in a certain zone is m and address 0 is the first sector for which polarity inversion is performed, polarity inversion is performed in a sector having a sector address of m × n (n is an integer). Done. Therefore, if the sector address is detected and decoded, basic information such as recognition of land or groove can be estimated.

However, there is a possibility that the recognition of the basic information as described above may be mistaken due to a reading error or the like at the time of reproducing the address data. Even if the current address cannot be read, the address itself is incremented, for example, by one, so that the address is predicted or corrected by reading the address in one or a predetermined number of previous sectors. However, the same problem arises in the case of the first track pull-in or in the pull-in after the track access in some cases. Further, it is desirable that the above basic information can be reproduced even when tracking servo is not applied. With the focus on, the recognition pattern 30
Is read out, the rotation control can be performed earlier, and a normal track crossing signal can be obtained even on a disk in which lands and grooves are alternately switched.

In particular, in a disk in which a land and a groove are continuous every other rotation, the operation must always be performed after always recognizing whether the next sector is a sector with polarity reversal, and the recognition operation is extremely performed. is important.
If erroneous address information is read by reading erroneous address information due to a scratch on the disk or the like, the servo will be deviated. Therefore, in an optical disk with such a polarity inversion, it is easy to recognize the presence or absence of this polarity inversion,
A reliable detection method is essential.

In an optical disk for recording,
Generally, a tracking method using one beam is used, so that a wobble pit for offset detection,
It has a mirror surface, and it is also important to obtain these detection timings. Further, the detection of the offset timing and the determination of the polarity must be performed reliably even in a state where a track shift has occurred. Correction processing of these track shifts should be performed at the time when a track offset occurs, and therefore, even if there is a slight track shift, the reproduction of the recognition pattern 30 must be reliably performed. . Needless to say, servo detection can be performed more stably if detection is possible even when tracking is not applied.

For this purpose, as shown in FIGS. 5, 6 and 9, the recognition pattern 30 is stored in one sub-header 5.
They are alternately shifted by one track pitch in the disk line direction. If the recognition patterns 30 are shifted by one track pitch in this way, the recognition patterns 30 are aligned in the radial direction of the disk within the same zone, so that the entire header section 6 is in a state as shown in FIG. I have.
With such a configuration, even if the tracking operation is biased during reproduction and the light spot is shifted to the inner circumference side or the outer circumference side of the disc, any of the recognition patterns 30 in one subheader 5 can be reliably reproduced. In particular, since the above-described header section 6 is arranged at a position shifted by about 1/2 pitch with respect to the information track, if one side cannot be reproduced with respect to the track offset, the sub-header 5 on one side becomes unreproducible. Then, there is a problem that the track offset cannot be removed in addition to the land groove determination.
Also, even when tracking is not applied,
The scanning of the light spot is, for example, as shown in FIG. 14, so that the reproduction can be sufficiently performed. If the scanning is alternately shifted by one track pitch as described above, the reproduction becomes easier.

However, when the recognition patterns 30 are arranged at equal intervals as shown in FIG. 14, for example, when tracking is not performed, if the light spot follows the scanning locus of β in the figure, Although the recognition pattern 30 in the second and fourth subheaders 5 can be reproduced,
In the case of the scanning locus of α in the figure, there is a possibility that the recognition pattern 30 cannot be reproduced. Here, the probability of becoming the scanning locus of α in the figure is considered to be sufficiently smaller than that in the case of the scanning locus of β in the figure. It is desirable to eliminate the possibility of the failure as much as possible, since it also leads to the failure of the pull-in.

Therefore, as shown in FIG. 15, for example, it is conceivable to provide a mirror surface portion 7 between the sub-headers 5 to shift the intervals between the sub-headers 5 so that the intervals between the recognition patterns 30 do not become constant. In this case, not only when the light spot traces the scanning trajectory of β in the figure, but also in the case of tracing the scanning trajectory of α in the figure,
Recognition pattern 3 of the third and fourth subheaders 5 from the left
0 can be reproduced.

In order not to make the interval between the recognition patterns 30 constant, in addition to the above-described insertion of the mirror surface portion 7, the VFO 29
It can also be dealt with by changing the length of. In this case, it is possible not only to increase the interval between the second and third subheaders 5 from the left but also to further increase the detection probability by changing the third and fourth intervals. Further, the detection probability of the recognition pattern 30 can be further increased by increasing the insertion frequency of the recognition pattern 30 to three or four instead of two in one subheader 5 as shown in FIG. is there.

As described above, the recognition pattern 30 can be reproduced even when the tracking servo is not applied, and the rotation control during the track access can be performed by obtaining the belonging information of the zone included in the recognition pattern 30. It has become possible.

Also, by reading the recognition pattern 30, it is also possible to obtain the detection timing of the mirror portion 7, so that the track offset can be removed in advance during track access or servo pull-in, so that the pull-in operation is smooth. (A pull-in operation with an offset of zero is possible).

Here, at the time of track access,
In general, the number of tracks to a target sector is calculated, and the number of tracks of a tracking error signal is counted to reach the target sector. At this time, the moving speed is calculated from the cross-track waveform of the tracking error signal, the speed is controlled so as to move at a predetermined speed, and the eccentricity of the disk is calculated using a sum signal equivalent to the reflected light amount. For example, subtraction of the amount of reverse swing is performed to perform accurate counting.

However, in the optical disk shown in FIG. 1A in which the land and the groove are continuous every other rotation, the track error signal reverses every other rotation, and
The tracking error signal 53 shown in FIG. 6 is reproduced. When the track count operation is performed in such a state,
In addition to the occurrence of a track count error in the reverse rotation portion in the figure, when performing the servo pull-in, there is a possibility that the track may be pulled into an adjacent track due to a difference in tracking polarity in the reverse rotation portion in the drawing. Therefore, the original tracking error signal 53 can be converted into the corrected correct tracking error signal 57 by calculating the polarity inversion timing 56 from the reproduced subheader recognition pattern 55 obtained from the reproduction envelope 54. It has become possible. In such a state, it goes without saying that the tracking pull-in operation is stabilized and the track count operation can be performed accurately.

When such a recognition pattern 30 is reproduced before the tracking operation or during the track access, the optical disk apparatus adopts the configuration shown in FIGS. FIG. 17 is a block diagram for performing rotation control in a state where the light spot is not tracking. 58 is a zone determination circuit, and 59 is a rotation control circuit. Here, from the intermittent reproduction envelope signal 54 obtained during the track traversal, the pattern matching circuit 18 detects the recognition pattern 30 via the PLL and the data detection circuit 17, and the zone determination circuit determination circuit 58 Then, based on the result of the zone assignment described in the recognition pattern 30, an instruction of the number of rotations is given to the rotation control circuit 59. With such a configuration, even during track access, rotation control can be performed in the middle, so that settling time can be shortened. The same applies to the case of pulling in a track.

Further, in the case of using the disc shown in FIG. 1A in which the tracking polarity is reversed every other rotation, it is necessary to reverse the tracking polarity.
The configuration is as shown in FIG. In FIG. 18, reference numeral 60 denotes a linear motor, 61 denotes a tracking polarity determination circuit, 62 denotes a track count circuit, and 63 denotes a feed control circuit. In this case, the reproduction envelope signal 54 at the time of track traversal detected by the adder 15 is output from the PLL and the data detection circuit 17.
, The pattern matching circuit 18 detects the recognition pattern 30, the tracking polarity information included in the recognition pattern 30 is recognized by the tracking polarity determination circuit 61, and the polarity inversion circuit 14 detects the tracking error signal. Perform polarity reversal. In addition, the inverting circuit 14
The track count operation is performed based on the corrected tracking error signal 57 corrected by the above, and the feed control of the linear motor 60 is performed via the feed control circuit 63.

Further, even in the state where such tracking is not performed, it is possible to correct the track offset as shown in FIG. 4, and it goes without saying that the track count operation becomes more accurate. This is because, when a track is accessed, the acceleration is applied to the objective lens, and the position of the objective lens is shifted without being determined at the actuator center, thereby causing a sensor offset due to the objective lens shift as described in the conventional example. . For this reason, there is a case where a deviation from a reference voltage necessary for binarization for counting the tracking error signal occurs and the binarization does not work.
For this reason, the correction operation is performed by operating the circuit in FIG. 4 even during track access and obtaining the detection timing of the mirror surface portion from the recognition pattern.

FIGS. 19 to 22 show the configuration of a pattern matching circuit. FIG. 19 shows the configuration of a pattern matching circuit using repetition of a recognition pattern. In the drawing, reference numerals 37 to 40 denote shift registers for serially inputting reproduction data, 41 and 42 denote pattern matching circuits, 43 denotes an AND circuit that outputs when two pattern matching circuits 41 and 42 match, and 46 denotes a subheader 5 itself. , A timing circuit 44, 45 for holding the sum signal level of the wobble pit, and 47 a difference circuit for obtaining the difference between the outputs 44, 45 of the sample and hold circuit. It is a differential amplifier.

FIG. 20 is a diagram obtained by adding an address ID detection circuit 48 for matching from the ID included in the recognition pattern 30 to the matching circuit of FIG.
Is an AND circuit for ANDing the two pattern matching circuits 41 and 42 with the address ID detection.

FIG. 21 is a block diagram of a circuit for judging whether or not the recognition pattern 30 is a recognition pattern when the recognition patterns 30 in two of the four subheaders 5 match each other. It is an inverting circuit.

FIG. 22 is a block diagram of a pattern matching circuit for obtaining a mirror surface detection timing by counting a PLL clock after detecting an address ID. Reference numeral 51 denotes an n-bit counter, and 52 denotes a tracking error signal on the mirror surface. Is a sample-and-hold circuit for holding.

In the above-described pattern matching circuit, the operation is performed by using a matching pit 32 using a modulation pattern not used for recording / reproducing data to determine whether or not the data is the same data. However, there is a possibility that recognition alone may be made erroneously at the time of erroneous detection due to a scratch, track offset, or the like. Therefore,
As shown in FIG. 18, the recognition pattern 30 of the subheader 5
However, it is possible to improve the reliability at the time of detection by utilizing the fact that the same pattern is repeated except for the ID part 33. At this time, for example, only when it is determined that both of the pattern matching circuits 41 and 42 match, the detection timing of the wobble pit can be obtained.

The improvement in reliability using such repetition information is also used, for example, in the subheader 5 to check whether or not the reproduction address data in the subheader 5 is correct. However, since the recognition pattern 30 includes the most basic information such as the motor rotation and the tracking polarity and needs to be detected even in a state where tracking is not performed, it is important to perform a check using a similar repetition pattern. I think that the. Further, if this is checked together with the confirmation of the incremented value in the ID section 33, the reliability can be further improved.

In this case, the address I as shown in FIG.
A D detection circuit 48 is required, and the address ID detection circuit 48 performs matching with, for example, 00011011 and performs determination processing. The pattern matching circuit 41 described above,
At 42, the data matching is performed between A and C and between B and D by the combination of the shift registers in the subheaders shifted from the center of the information track in the disk radial direction and between the front and rear directions. This is because they are compared.

When pattern matching is performed only with the subheader 5 shifted to one side from the information track center, only the comparison between the shift registers A and C as shown in FIG. 21 is required, and the wobble pit is detected by detecting the ID33. It is to get the timing. Here, the ID number is set in an n-bit counter, and the wobble pit detection timing is obtained by counting a predetermined number by a PLL clock. However, when the detection of the subheader 5 is performed partway, the detection order of the wobble pits is reversed, so that the polarity inversion circuit 50 in FIG.
The timing is inverted and used. As a result, an accurate tracking error signal including no offset can be obtained from the sum signal.

Further, in the case of performing mirror surface correction in the same manner as in FIG. 21, it is possible to adopt a configuration as shown in FIG.
In this case, similarly to FIG. 21, the output of the n-bit counter is connected to the sample and hold circuit 52, and the tracking error signal is sampled and held when passing through the mirror surface. With such a configuration, even when the tracking servo is not applied, it is possible to detect the recognition pattern 30 and perform, for example, offset correction in the mirror surface section 7 or switch the tracking polarity.

The system for improving the reliability from the subheader 5 on one side shown in FIGS. 20 and 21 has lower reliability than the system shown in FIG. 19 and the like in which matching is performed from all data. This is effective in a system where a recognition pattern cannot be completely obtained, such as a state where no recognition pattern is available.

[0089]

According to the optical disc of the present invention, since the recognition pattern of the land or the groove is provided in the recognition pattern, the polarity reversal in the disc in which the land and the groove are continuous can be reliably detected, and the land and the groove can be detected. In a track error signal of an optical disk which is continuous every other track, a continuous track crossing signal similar to that of a conventional spiral disk can be obtained.

Further, in the optical disk apparatus and the optical disk tracking method of the present invention, it is possible to reliably detect the polarity reversal in a disk in which lands and grooves are continuous.

[Brief description of the drawings]

FIG. 1 is a diagram showing a header part of a normal spiral disk and a disk in which land grooves are switched every other track in the optical disk according to the first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a zone on the optical disc of the first embodiment.

FIG. 3 is a diagram showing a configuration of a header section in the optical disc of the first embodiment.

FIG. 4 is a block diagram of a track offset correction circuit using a wobble pit and a mirror portion in the optical disc device of the first embodiment.

FIG. 5 is a diagram showing a pit arrangement of a header portion in the optical disc of the first embodiment.

FIG. 6 is a diagram showing an arrangement of recognition patterns on the optical disc of the first embodiment.

FIG. 7 is a diagram showing an example of a recognition pattern on the optical disc of the first embodiment.

FIG. 8 is a diagram showing a pit configuration of a recognition pattern on the optical disc of the first embodiment.

FIG. 9 is a diagram showing a configuration of a recognition pattern on the optical disc of the first embodiment.

FIG. 10 is a diagram showing an internal configuration of a recognition pattern on the optical disc of the first embodiment.

FIG. 11 is a diagram showing a configuration when a recognition pattern on the optical disc of the first embodiment is configured by 4 bytes.

FIG. 12 is a diagram showing a configuration in a case where a recognition pattern on the optical disc according to the first embodiment is configured by 3 bytes.

FIG. 13 is a diagram showing a configuration in a case where a recognition pattern on the optical disc of the first embodiment is configured by 2 bytes.

FIG. 14 is a diagram showing a recognition pattern and a light spot scanning trajectory when traversing a track in the optical disc according to the second embodiment of the present invention.

FIG. 15 is a diagram showing a recognition pattern in which an interval is changed on the optical disc of the second embodiment and a light spot scanning trajectory when traversing a track.

FIG. 16 is a diagram showing a state of reproduction of a recognition pattern and a tracking error signal when a track is traversed on the optical disc of the second embodiment.

FIG. 17 is a block diagram showing a rotation control system at the time of traversing a track in the optical disc device of the second embodiment.

FIG. 18 is a block diagram for performing polarity reversal and track counting operations when traversing tracks in the optical disc device of the second embodiment.

FIG. 19 is a block diagram showing a pattern matching circuit of a recognition pattern in the optical disc device of the second embodiment.

FIG. 20 is a block diagram showing a pattern matching circuit of a recognition pattern that also uses matching by ID in the optical disc device of the second embodiment.

FIG. 21 is a block diagram showing a pattern matching circuit of a recognition pattern using only one side subheader in the optical disc device according to the second embodiment.

FIG. 22 is a block diagram for performing pattern matching and offset correction of a recognition pattern using only one subheader in the optical disc device of the second embodiment.

FIG. 23 is a diagram showing a header section of a conventional optical disc.

FIG. 24 is a diagram illustrating the principle of generation of an offset by a conventional push-pull tracking method.

FIG. 25 is a diagram showing a mirror surface and wobble pits of a conventional optical disc.

FIG. 26 is a block diagram of a track offset correction circuit using a mirror surface of a conventional optical disk device.

FIG. 27 is a waveform diagram of an output signal obtained from a conventional wobble pit.

FIG. 28 is a control characteristic diagram when a tracking error signal obtained by a conventional wobble pit and a push-pull method is used.

FIG. 29 is a block diagram of a track offset correction circuit using wobble pits of a conventional optical disc device.

[Explanation of symbols]

1 groove track, 2 land tracks, 3 headers, 4 headers for switching land and groove, 5 subheaders, 6 headers, 7 mirrors, 8 optical disks, 9 disk motors, 10 optical heads, 11 optical detectors, 13 IV Amplifier, 14, 50 polarity inversion circuit, 15, 28 addition amplifier, 16, 26, 27, 47
Differential amplifier, 17 PLL data detection circuit, 18, 4
1,42 pattern matching circuit, 19 polarity inversion position detection circuit, 20 mirror surface detector, 21, 43,49 AND circuit, 22 wobble pit detection circuit, 23-2
5, 44, 45, 52 sample hold circuit, 29
VFO, 30 recognition pattern, 31 address data,
32 pit for matching, 33 ID, 34 zone judgment part, 35 mirror surface part, 36 head amplifier, 37-4
0 shift register, 46 timing circuit, 48 address ID detection circuit, 51 n-bit counter, 58
Zone determination circuit, 59 rotation control circuit, 60 linear motor, 61 tracking polarity determination circuit, 62 track count circuit, 63 feed control circuit.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Komawaki 2-3-2 Marunouchi 2-chome, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (56) References JP-A-7-29185 (JP, A) International Publication 96/25736 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B ^7/ 007-7/013 G11B 7/09-7/095 H04N 5/85

Claims (3)

(57) [Claims] 1. A continuous information track is formed at a switching portion appearing every other rotation while a land track and a groove track are switched, and the information track is divided into a plurality of zones according to a position in a radial direction. An optical disc, wherein the information recording track is divided into a plurality of sectors each having an information recording unit length in the scanning direction, and a subheader is provided at the head of each sector, and the subheader is arranged in the scanning direction of the information recording track. An optical disc, wherein a plurality of discs are arranged at a distance of about 1/2 pitch in the radial direction and a recognition pattern for obtaining a timing of reversing the polarity of an information recording / reproducing portion of the sector is arranged in the subheader section. 2. A continuous information track is formed at a switching portion appearing every other rotation while a land track and a groove track are switched, and the information track is divided into a plurality of zones according to the position in the radial direction. An optical disc, wherein the information recording track is divided into a plurality of sectors each having an information recording unit length in the scanning direction, and a subheader is provided at the head of each sector, and the subheader is arranged in the scanning direction of the information recording track. A plurality of discs are shifted by about 1/2 pitch in the front and rear in the radial direction, and a recognition pattern for obtaining the timing of reversing the polarity of the information recording / reproducing portion of the sector is track-accessed to the optical disc arranged in the sub-header section. Recognizes the above recognition pattern from the output signal, and based on the recognition result, the polarity of the tracking error signal Switching method of optical disc. 3. A continuous information track is formed at a switching portion appearing every other rotation while a land track and a groove track are interchanged, and the information track is divided into a plurality of zones according to the position in the radial direction. An optical disc, wherein the information recording track is divided into a plurality of sectors each having an information recording unit length in the scanning direction, and a subheader is provided at the head of each sector, and the subheader is arranged in the scanning direction of the information recording track. When the information is read from an optical disk device using an optical disk in which a recognition pattern for obtaining the timing of the polarity inversion of the information recording / reproducing portion of the sector is arranged in the subheader portion, the plural patterns are arranged shifted by about 1/2 pitch in the radial direction. Reproducing means for reproducing a reproduced signal; and a recognition means for recognizing a recognition pattern from the reproduced signal reproduced by the reproducing means. An optical disc device comprising: recognition means; and switching means for switching the polarity of a tracking error signal based on a result of the recognition means.