JPH1011759A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disk medium capable of surely detecting the junction point between a land track and a groove track in a single spiral land/ groove recording optical disk and also capable of correctly performing a tracking offset compensation. SOLUTION: In a header area 22, physical address area PID is recorded four times and a mirror mark arer 23 constituted of an emboss pit which does not appear in the modulation signal of data and is long and mirrors is arranged hehind the PIDs. Then. the mirror mark area 23 is consistuted of a pattern in which two mirrors exist in a sector including a land/groove polarity changeover and is constituted of such different patterns that one mirror exists and whether a sector is the sector of one sector before the sector including the polarity changeover or the sector of two sectors before the polarity changeover or other sector can be discriminated in the other sectors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable optical disk which records signals on both a recording track of a concave portion formed by a guide groove and a recording track of a convex portion formed between the guide grooves. Things.

[0002]

2. Description of the Related Art Existing phase-change optical disks record data only in grooves called grooves. The land between the groove tracks plays a role in guiding during tracking and suppressing crosstalk from an adjacent groove track. Here, if data is recorded also on the land, the track density can be doubled while keeping the groove width the same, but since the crosstalk increases, the recording density will not increase so much even if land / groove recording is used. Had been However, the step between the groove and the land is λ / 6 (λ
Is about the wavelength of the light source), the crosstalk between adjacent tracks can be suppressed.
There has been a history of high density recording by groove recording. 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 land / groove recording.

[0003] It is known that an optical disk for performing land / groove recording has a concentric configuration. When recording for one round of the disk, a track jump is performed, and an adjacent track (for example, if the current track is a groove track, an adjacent track is used). Start writing). In this case, since each sector is always managed by a sector address, a buffer memory or the like can be used to operate without any problem when only recording and reproducing data which may be discontinuous such as computer data.

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

[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. That is, when switching between lands and grooves, access from the inner circumference to the outer circumference of the disk is required, which takes time. For example, if this operation is divided into several zones in the radial direction of the disk and the land and groove are switched in units of zone,
Recording or playback must be interrupted for a considerable amount of time.

FIG. 7 is a diagram showing details of a header section of a conventional land / groove recording disk.
7A shows the case where the header 6 is formed on both the land track 5 and the groove track 4, and FIG. 7B shows the case where the header 7 is formed at the boundary between the land 5 and the groove 4. I have.

The above-mentioned header portion is an uneven portion physically formed to represent address information of a sector which is a unit for recording data. Specifically, a pit with the same height as the land, or a pit with the same depth as the groove,
It is formed in a header part without a track. There are several methods for forming prepits suitable for land and groove. Among them, the main methods are a dedicated address method having a dedicated address for each track as shown in FIG.
As shown in FIG. 7B, there are two types of intermediate address systems having intermediate (shared) addresses.

In the above-mentioned 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, which is described in JP-A-6-176404. Using the same laser beam as that used to form the track, pits can be formed by shifting the position in the radial direction by ト ラ ッ ク of the groove pitch. 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.

Here, a conventional land / groove recording optical disk is disclosed in, for example, Japanese Patent Application Laid-Open No.
No.-57859 is disclosed.
As shown in FIG. 8, the grooves 4 and the lands 5 are formed by the guide grooves cut on the disk substrate, and the recording film 1 is formed thereon. The recording pits 2 are recorded on the recording films of both the groove 4 and the land 5. The grooves 4 and the lands 5 form continuous recording tracks on the disk. The focused spot 3 of the optical disk device for recording and reproducing the recording medium records / reproduces information while scanning on one of the recording tracks. In the conventional land / groove recording format, since the guide grooves are continuous on the disk, the recording tracks of both the groove 4 and the land 5 are continuous, and each of them forms a continuous recording spiral.

Next, FIG. 9 shows that a groove track 4 corresponding to one circumference of the disk and a land track 5 provided between the grooves and corresponding to one circumference of the disk are alternately connected to each other to form one recording. FIG. 3 is a diagram showing a configuration of an optical disc having a format in which a spiral is formed.
As an optical disc having a format in which the groove tracks 4 and the land tracks 5 are alternately connected to form one recording spiral as shown in FIG.
For example, JP-A-4-38633 and JP-A-6-274
No. 896 discloses this. Here, the format of such an optical disc is a single spiral land / groove format or SS-L
/ G format.

The SS-L / G format disc is
Since the recording tracks are continuous on the disk, it has a great feature that it is suitable for continuous recording and reproduction of data. For example, in video file applications, continuous recording and reproduction of data is essential. However, in the conventional land / groove recording as shown in FIG. 10, since the land track and the groove track each constitute one recording spiral, for example, when recording / reproducing from the land track to the groove track is continued. In at least one place on one surface of the disk, continuous recording / reproduction is interrupted by an access connecting between a land track and a groove track. The same applies to the case where recording and reproduction are continuously performed from the groove track to the land track. In order to avoid such interruption of recording and reproduction, it is necessary to add a buffer memory, which is a cost increase factor.
This is not necessary if a single spiral land / groove format is used.

In order to apply tracking servo to an SS-L / G format disk, a connection point connecting recording tracks in a groove portion and recording tracks in an inter-groove portion is accurately detected, and the tracking servo polarity is detected there. It is necessary to switch the servo polarity between setting to track the recording track in the groove and setting to track the recording track in the groove.

FIG. 10 is a diagram showing a configuration of a connection point between a recording track in a groove portion and a recording track in an inter-groove portion described in JP-A-7-57302. In the figure, (a) shows an example in which a flat portion is provided at a connection point, and (b) shows an example in which a predetermined bit pattern is provided. Here, in the disk format in which the switching of the servo polarity is detected by the flat portion or the bit pattern, the following problem occurs.
Practical configuration is not possible.

For example, in such a case, the flat portion and the bit pattern can be generally formed only in the header portion of the sector. Therefore, in the format shown in FIG. 10, only one sector can be formed in one round of the disk of the information track. Generally, the number of bytes in one sector is
Since it is not possible to increase the size in consideration of searchability, it is common sense to configure a plurality of sectors in one circumference of the disk. Therefore, one sector in one circumference of the disk is extremely impractical. Further, if a plurality of sectors are formed in one circumference of the disk, the flat portions and the bit patterns must be arranged in each sector. As a result, the flat portions and the bit patterns And discriminate
Needless to say, a method for detecting a new switching point is required. Therefore, in the above-described detection of the switching point, a method of discriminating patterns from a plurality of types as described in the following embodiments is indispensable, instead of determining whether or not a flat portion or a bit pattern exists. It becomes.

As described above, the format shown in the conventional ISO magneto-optical disk in which the pre-formatted identification information indicating the address and the like and the information recording area for recording the user data are separately arranged on the recording track. In the case of adopting the method, there is a problem that the identification information and the connection point between the groove and the groove are erroneously detected as being represented in the same recording form. In the example disclosed in Japanese Unexamined Patent Publication No. 7-57302, there is no place for the pit row as shown in FIG. However, when the identification information to be preformatted is arranged in all the sectors in the recording track, it is necessary to ensure that the connection point between the groove portions and the inter-groove portion can be reliably determined in the method of adding the identification information.

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 land and groove configuration 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.

Particularly, in a recordable optical disk,
A one-beam optical system is used to increase the light use efficiency. One example is the so-called push-pull method. In this push-pull method, various methods for removing the sensor offset due to the lens shift due to the lens shift are being studied.To avoid crosstalk and cross-erase, it is necessary to adjust the track according to the land and groove tracks. It is necessary to perform offset compensation of different magnitudes.

As shown in FIG. 11, the push-pull tracking is a method of detecting a track error using a diffraction distribution of a light spot irradiated on a pre-groove and forming a servo system. There is a problem that offset occurs due to the above. In FIG. 11, 1
0 is an optical disk, 11 is a disk motor, 16 is a photodetector, 17 is a laser diode, 14 is a half mirror, 1
Reference numeral 3 denotes an objective lens, and reference numeral 12 denotes an actuator coil for driving the objective lens. For example, since the light distribution 15 on the photodetector 16 is shifted by an inclination of 0.7 ° or an eccentricity of 100 μm (equivalent to the translation of the objective lens 17 of 100 μm indicated by a dotted line in FIG. 11), a general In this case, an offset of about 0.1 μm occurs.

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 system or a recording / reproducing system.

Therefore, a wobble pit method for preparing pits shifted from the track pitch by about 1/2 pitch in the radial direction of the disk is conventionally known. FIG. 12 shows the reproduction output signal in the wobble pit, which was announced in “Optical Memory Symposium '85”, pages 181 to 188, “Composite Track Wobbling Optical Disk Memory”, edited by the Photonics Industry Promotion Association. in this case,
As shown in FIG. 12, for the track center b, a
When the light spot passes through a portion closer to the upper pit 8 as shown in FIG. 5, an output signal as shown by a dotted line e is obtained from the wobble pit, and when the light spot passes through a portion closer to the lower pit 9 as shown in FIG. Is obtained, and a value obtained by subtracting the signal amplitude value of the pit 9 at the subsequent stage from the signal amplitude value of the pit 8 at the preceding stage indicates the magnitude and direction of the track shift amount. 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. However, in this case, since a track error signal due to the wobble pit cannot be continuously obtained, a sufficient control band is generally secured by using the push-pull method together.

[0022]

Since the conventional single spiral land / groove recording optical disk medium is constructed as described above, when the sector recording format is to be adopted, the connection point between the land track and the groove track is determined. There is a problem that it is difficult to reliably detect.

In a recordable optical disk apparatus, 1
Since an optical system that performs tracking with a beam is used, there is a problem that an offset occurs in the tracking sensor due to the shift of the objective lens.

The present invention has been made in order to solve the above problems, and has a single spiral land /
In an optical disk of a groove format, an optical disk having a physical format capable of improving the reliability of reading identification information is obtained in order to reliably detect a connection point between a land track and a groove track and switch the polarity of tracking servo. The purpose is to:

It is another object of the present invention to provide an optical disk medium having a physical format capable of accurately performing tracking offset compensation for an objective lens shift even when a one-beam tracking detection method is used.

[0026]

According to the optical disk of the present invention, both a groove formed circumferentially on a disk substrate and an inter-groove between the grooves are used as information recording areas.
In an optical disc in which one recording spiral is formed by alternately connecting recording tracks of the groove corresponding to a circumference and recording tracks of the inter-groove corresponding to one circumference of the disk, the recording tracks are an integral number. The recording sector includes a header area preformatted so as to represent address information and the like, and the header area includes address information of the recording sector and has a track pitch from a track center of the recording sector. And a mirror area consisting of the address information of the recording sector and a mirror area including a mirror, and a half of the track pitch of the recording sector from the center of the recording sector to the inner circumference of the disk. The mirror mark area of the header area. In the sector that includes two mirrors in the sector including the polarity switching, the other sector includes one mirror and is located immediately before the sector including the polarity switching. Alternatively, the sector immediately before the polarity switching,
Alternatively, it is constituted by a different pattern that can be distinguished from other sectors.

Further, the length of the mirror included in the mirror mark area is longer than the length which can be sufficiently distinguished from the longest pit length of the data portion.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. Embodiment 1 FIG. The present embodiment relates to an optical disk medium of a single spiral land / groove recording (SS-L / G) format divided into a plurality of zones by a circumferential boundary.

Hereinafter, a sector area layout for the optical disc medium according to the first embodiment will be described.
A sector is a unit of data that a disk drive can read and write at one time. FIG. 1 is a diagram showing a configuration of a sector of an optical disk medium according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a layout of sectors of the optical disk medium according to the first embodiment of the present invention.
As shown in the figure, one sector (2697 bytes) records a pre-pit area (133 bytes) including two areas of a header area (128 bytes) and a mirror mark area (5 bytes), and 2048 bytes of user data. And an information recording area (2564 bytes).
The information recording area is a gap (17 to 19 bytes), VF
O3 (50 bytes), data area (2418 bytes),
It consists of guard data (30 bytes) and a buffer (47 to 49 bytes). Errors in the sector length due to errors in the write clock and disk rotation speed are corrected by the buffer at the end of the sector.

FIG. 3 is a diagram showing a layout of a header area of the optical disk medium according to the first embodiment of the present invention.
As shown in the figure, the header area includes PID1, PID2,
It consists of PID3 and PID4 areas. PID1 is VF
O (Variable Frequency Osci)
llator) 1, address mark (AddressM)
ark: AM), Physical id (Pid)
1. IED (ID Error Detection)
code) 1 and Postamble (PA).
PID2 is VFO2, AM, Pid2, IED2, P
A. PID3 is VFO1, AM, Pid3,
It consists of IED3 and PA. PID4 is VFO2, A
M, Pid4, IED4, and PA. PID1 and P
ID2 is arranged on the boundary between the groove track and the inter-groove track adjacent on the outer peripheral side. PID3 and PID4 are arranged on the boundary between the groove track and the inter-groove track adjacent on the inner peripheral side. The mirror mark area is arranged between PID4 and the gap. The mirror mark area is arranged on the boundary between the groove track and the inter-groove track adjacent on the inner peripheral side.
Note that the number described in each area in FIGS. 2 and 3 indicates the number of bytes in that area.

The VFO will be described. The header area has two VFO1s and two VFO2s. There is one VFO 3 in the information recording area. These VFOs are used to generate a read channel bit clock.
L (Phase-Locked Loop) is used for the pull-in operation. VFO1 and 2 are pre-pitted, while VFO3 is written at the time of data recording. As shown in FIG. 3, VFO1 is 36 bytes, and VFO2 is 8 bytes. PID1 and PID2 pairs, PID3 and PI
The set D4 is radially offset. The VFO1 in PID1 and PID2 is compared with the VFO2 in PID2 and 4 by PLL.
A longer area is desirable because it is where the retraction starts.

V used in the optical disk medium of the present embodiment
The FO uses a pattern of 1000100010001. Conventionally, for example, ISO138142
(130 mm optical disk standard: modulation method is 1-7 modulation)
The VFO used at 10
1010 is used. According to this, since 8-16 modulation is used in the present embodiment, 10010010
01 ... can obtain the highest frequency,
There is a disadvantage that the amplitude of the reproduction signal from the disk is reduced.
In a conventional ISO standard optical disc, there is a sector mark (SM) before the VFO, and it is easy to find the head of the sector. Therefore, even in the VFO having the highest frequency, it is easy to pull in the PLL. However, in the present embodiment, since the head of the sector is a VFO, it is difficult to catch it. On the other hand, if the frequency is too low, that is, if the interval of “1” is too wide, it is difficult to generate the channel bit clock by the PLL. In order to minimize both problems, the above-mentioned pattern "100010001..." Is used. This pattern is common to VFOs 1, 2, and 3.

It is assumed that the number of bytes of VFO1 is k bytes. In the case of using so-called 8-16 modulation for converting 8-bit data into 16 bits as a modulation method, k × 8 × 2 = 1
The length is 6 k channel bits (channel bits represent bits after modulation). Since “100010001...” Is used as the VFO pattern, the space and mark change points are 16 k / 4 = 4 k
(Location). The size of the VFO described in ISO138142 is 26 bytes. In this case, the space and the change point of the mark are 26 × 8 × 3/2/2.
= 156 (locations). According to this, 4k = 156
If k = about 39 bytes, it is sufficient. Therefore, in the present embodiment, the length is set to 36 bytes from the establishment time of the slice level of the PLL or the auto slicer.

The address mark (AM) will be described. AM is provided between VFO and Pid in the PID area. This is for achieving byte synchronization after completing bit synchronization in the previous VFO. Also, the AM is configured using a pattern that does not appear in the modulation rule so that the device does not erroneously capture data and the like in the user data area.

A description will be given of Pid. The Pid area following the address mark has the number of sectors, that is, a physical address. Its size is 4 bytes, the first 3 bytes contain the number of the preceding sector, and the other 1 byte contains various information for that sector. It is desirable that the address information is an integer from the viewpoint of easy management and construction of the control F / W. If it is 2 bytes, it is 2536 to 65536
Can be managed, and one sector is 2048 user bytes, so that 2048 × 65536 = 1342177
28, and a capacity of about 134 Mbytes can be managed.
However, the capacities of various storage media at present are on the order of giga, and this is not sufficient. Therefore, if there are three bytes, it is 2 24 which is 16777216
2048 × 16777216 =
34359738368, and the capacity of about 34.36 Gbytes can be managed. Therefore, the address is set to 3 bytes for sector management.

The IED will be described. IED
The area is an area for a code for detecting whether or not Pid has an error as described above. Its size is 2 bytes. If an error is detected by this code, four Pids are arranged in the header area at the head of one sector, and an address can be specified by a Pid in which no error is detected.

The PA will be described. In the pre-pit area, a portion having a pit is called a mark portion, and a portion having no pit is called a space portion. When the PID is recorded, the end of the IED may be a mark part or a space part. For this reason, if the VFO is recorded immediately after the IED without inserting the PA, the VFO pattern cannot be uniquely determined depending on whether the end of the IED is a space or a mark. PA is provided for this purpose, and the end of PA always ends with a space. For this purpose, several PA patterns are prepared according to the modulation rule.

Next, a method of adding the address value of the PID in the header area will be described. FIG. 4 shows Embodiment 1 of the present invention.
FIG. 3 is a schematic diagram for explaining the arrangement of PID areas in recording sectors of an optical disc medium and its address value.
The address of the groove 4 is added to the PIDs 1 and 2, which are arranged in the header area 22 before the information recording area 20 and displaced from the center of the groove to the outer periphery by の of the groove width. The address of a land is the one of the recording track of the land.
In the header area before the information recording area of the recording track of the groove on the outer circumference side, PIDs 3 and 4 which are displaced from the center of the groove to the inner circumference side by 1/2 of the groove width are added. As a result, the addresses of the lands are added to the PIDs 3 and 4 arranged in the header area before the information recording area, displaced from the center of the lands by の of the groove width toward the outer periphery.

This is because the tracking offset generated when cutting the master disc is considered to be smaller when cutting the groove address and the land address at the same time when cutting the recording track of the groove. From the viewpoint of the tracking offset characteristics, if the tracking offset is smaller when cutting the groove address when cutting the groove recording track and cutting the land address when cutting the land recording track, the cutting can be performed separately. .

Next, a description will be given of a method of adding an address at a connection portion between a land and a groove, which is arranged once in one round of the disk in the radial direction of the disk and exists. FIG. 5 is a schematic diagram for explaining the arrangement of the PID area in the recording sector at the boundary between the optical disk medium land and the groove and the address value thereof according to the first embodiment of the present invention. SS
-In the L / G format disc, there is a boundary line connecting the recording track of the groove and the recording track of the land at one place in the radial direction. The arrangement of the header area is the same as the arrangement of the header area except for the boundary, and the front part is one groove width from the groove.
/ 2 is displaced toward the outer peripheral side. The rear portion is displaced from the groove toward the inner peripheral side by half the groove width. In addition to the addition of the address value, the groove address is added to the front identification signal which is displaced from the groove immediately before the information recording portion to the outer periphery by の of the groove width in the same manner as the portion other than the boundary portion. The address of the land is added to the rear identification signal which is displaced from the land immediately before the information recording portion by half the groove width toward the outer peripheral side.

As shown, when the address of a certain recording sector (groove in this figure) is #n (integer) and the number of sectors in one track is N (integer), the address #
The sector address of one round of the track from sector n is #
(N + N). When the circuit has made another round, # (n + 2
N), and thereafter, # (n + 3N) and # (n + 4N), except for the boundary portion, the physical shape of the sector alternates with the glue brand, but the address value linearly changes. When looking at the continuity before and after the boundary, the sector of the groove is the first half of the header area displaced from the groove toward the outer periphery by half the groove width, and the sector of the land is 1 / the width of the groove from the land.
The address can be specified from the latter half header area displaced to the outer periphery by two.

With the arrangement of the header area as described above, track offset correction can be performed. When a pair of track offset detection pits displaced by a fixed amount from the track center to the left and right is provided as in a sample servo optical disk, the tracking offset amount can be detected. When the light beam passes through the middle of the track offset detection pit pair, the reproduced signal amplitude of the detection pit pair becomes equal. If you are offtracking to one side,
Since the reproduction signal amplitude of the pit on one side increases and the reproduction signal amplitude of the pit on the other side decreases, the light beam passes through the center of the track by detecting and correcting the track offset amount of the light beam. Can be controlled as follows. In the present invention, the same principle and effect are
It can be incorporated into a single spiral land / groove recording format.

Now, it is assumed that the light beam enters the identification signal area of the next groove recording sector from the information recording area in the specific groove recording sector. Since the head of the identification signal is shifted to the outer periphery of the disk by の of the groove width, a tracking error signal corresponding thereto is output. After a while, since there is an identification signal shifted by １ ／ of the groove width on the inner circumference of the disk, a tracking error signal corresponding to the identification signal is output.
Ideally, if these two error signals are detected symmetrically, it means that the center of the track is being scanned. Therefore, it is possible to control the servo around the track center by using the repetition of the identification signal shifted to the inner circumference and the outer circumference.

In the optical disk of the single spiral system configured as described above, since the tracking polarity is switched once per rotation, if the tracking switching point cannot be detected, a track shift occurs.
Not only will the sector immediately after the polarity switch become unreadable,
Since the track access is performed again, there is a problem that a rotation wait or the like newly occurs. Therefore, it is needless to say that the timing at which the tracking polarity is inverted must be reliably detected. However, compared to a magneto-optical disk or the like having a zone CAV configuration in which the disk rotation speed is always constant, in an optical disk using a phase change medium having a high linear velocity dependence, the disk rotation speed must be changed for each zone. Therefore, the polarity switching timing of the tracking does not always appear at a constant time interval, and a means for accurately detecting the polarity inversion timing is required. Therefore, by providing the following mirror mark area, the above timing can be accurately detected.

Here, the mirror mark area will be described. At the end of the header area is a mirror mark area. This area was created to quickly find the joint between the land track and the groove track. This area is composed of 5 bytes and is configured by combining a mirror section and a groove. The mirror is neither a prepitted groove nor a mark. The groove is a prepitted groove.
Further, a code indicating the first or last sector of the track is recorded by a combination pattern of the mirror portion and the groove, and by reading this code, the track boundary between the groove and the land can be specified. The combination pattern employs a relatively rough mark so that it can be easily read. Such a mirror pattern is the same pattern between sectors adjacent in the disk radial direction in one zone. For this reason, the mirror section is also a mirror section in a track adjacent to the mirror section, and the mirror sections are continuously arranged in the radial direction in the same zone. For this reason, the reflected light from the light spot is totally reflected as compared with a land portion of the information recording area or a portion where no pit is formed in the embossed area, and the recognition becomes easier.

FIG. 6 shows the mirror mark area 23.
In the figure, (a) shows a pattern of a mirror mark area in a sector in which tracking polarity switching is required, and (b) shows a mirror in a sector immediately before the sector for which polarity switching is performed. (C) shows the pattern of the mirror mark area in the sector immediately before the sector for which the polarity is switched, and (d) shows the pattern of the mirror mark area in the other sectors.

As shown in FIG. 6, in the pattern of the mirror mark area 23, a mirror (mirror surface) 28 having a length of 1.5 bytes or 2 bytes is used. By using such a long mirror pattern (mirror pattern), detection becomes easier. However, if the length of the mirror 28 is too long, it is difficult to obtain a track crossing signal when the light spot accesses the track direction at a high speed, so that there is a problem that the counting accuracy in performing the track count is deteriorated. Occurred. Therefore, here, the maximum length of the mirror is set to be 2 bytes or less. Further, as shown in FIG. 6, not only the sector including the polarity reversal and the other sectors are determined, but also the sector immediately before or two sectors before the sector including the polarity reversal can be determined. I have. With this configuration, in the sector including the polarity reversal, even if the pattern in FIG. 6A cannot be determined due to a scratch on the disk or the like, the previous or next previous sector is recognized. Then, when the embossed area 19 is recognized, it can be inferred that this sector is a sector including polarity inversion.
With this configuration, it is possible to reliably detect the timing at which the tracking polarity is reversed and to improve the detection reliability. Since the mirror mark area is always located at the rear of the header area of each sector, the position of the mirror mark area can be determined after recognizing the header section during reproduction.

The length of the mirror included in the mirror mark area 23 is set to a length that can be sufficiently distinguished from the longest pit length of the data portion. For this reason, it is possible to easily and surely detect the mirror mark, and it is possible to invert the reliable and stable tracking polarity. In addition, the mirror mark can be reliably detected even during track access. Furthermore, if the length of the mirror mark is set to a length that enables a track groove crossing signal to be reliably obtained during track access, the mirror mark can be reliably detected even during track access.

In the above embodiment, the PID
1 and PID2 are displaced toward the outer periphery of the disk, and PID3
Although PID4 and PID4 are configured to be displaced toward the inner periphery of the disk, it is needless to say that PID1 and PID2 may be displaced toward the inner periphery of the disk, and PID3 and PID4 may be configured to be displaced toward the outer periphery of the disk. No.

[0051]

Since the present invention is configured as described above, it has the following effects. In the optical disc of the present invention, the sector including the polarity switching is constituted by a pattern in which two mirrors are present. In the other sectors, one mirror exists and is located immediately before the sector including the polarity switching. Of the SS-L / G disk, the connection between the land track and the groove track of the SS-L / G disk can be easily formed. It became possible to detect. Also, by recognizing the sector immediately before or after the switching point and not recognizing the mirror pattern of the sector including the polarity switching, if the passage of the header area can be confirmed, it is assumed that the sector includes the switching point. Now you can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a sector of an optical disc according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a layout of sectors of the optical disc according to the first embodiment of the present invention;

FIG. 3 is a diagram showing a layout of a header area of the optical disc according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining an arrangement of a PID area in a recording sector of the optical disc according to the first embodiment of the present invention and an address value thereof;

FIG. 5 is a diagram showing a PI in a recording sector at a boundary between a land and a groove of an optical disc according to the first embodiment of the present invention;
FIG. 4 is a schematic diagram for explaining the arrangement of D areas and their address values.

FIG. 6 is a diagram showing a pattern of a mirror mark area of the optical disc according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a header section of a conventional optical disc.

FIG. 8 is a view showing a conventional land / groove recording optical disk.

FIG. 9 is a diagram showing a configuration of an optical disk having a conventional SS-L / G disk format.

FIG. 10 is a diagram showing a configuration of a conventional optical disk recording medium.

FIG. 11 is a diagram illustrating the principle of generation of an offset by a conventional push-pull tracking method.

FIG. 12 is a diagram showing mirrors and wobble pits of a conventional optical disc.

[Explanation of symbols]

1 recording layer, 2 recording pits, 3 focused spots, 4
Groove, 5 land, 6, 7 header, 10 optical disk, 11 disk motor, 12 actuator coil, 13 objective lens, 14 half mirror, 15
Light distribution, 16 light detectors, 17 laser diode, 18
Optical head, 19 embossed area, 20 information recording area, 21 sector, 22 header area, 23 mirror mark area, 24, 25, 26, 27 PDI area, 28
Mirror, 29 groove in mirror mark.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhiko Nakane 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Yoshinori Ishida 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (2)

[Claims] An information recording area includes a groove formed circumferentially on a disk substrate and an inter-groove between the grooves, and a recording track of the groove corresponding to one circumference of the disk and one circumference of the disk. In an optical disc in which recording tracks in the inter-groove portions corresponding to minutes are alternately connected to form one recording spiral, the recording tracks are composed of an integer number of recording sectors, and the recording sectors are, for example, address information. The header area includes address information of the recording sector, and is displaced from the center of the track of the recording sector to the outer side or the inner side of the disk by half the track pitch from the center of the recording sector. And a mirror area including the address information and the mirror of the recording sector, and a track pitch from the track center of the recording sector. The mirror mark area is arranged at the rear of the header area, and is composed of a pattern in which two mirrors are present in a sector including a polarity switch, which is displaced toward the inner circumference side or the outer circumference side of the disk by half the length. In the other sectors, there is one mirror and it is possible to determine whether the sector is one sector before the sector including the polarity switching, two sectors before the polarity switching, or another sector. An optical disc composed of different patterns. 2. The optical disk according to claim 1, wherein a length of a mirror included in the mirror mark area is longer than a length that can be sufficiently distinguished from a longest pit length of a data portion. .