JP2001101666A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk with which stable tracking control of high accuracy and high-density recording and reproducing are possible. SOLUTION: Grooves 15 and lands 16 are alternately formed at every one rotation and pits 17aG and 17aL indicating address information 13aG and 13aL of the grooves 15 and the lands 16 are respectively formed on the central axes of the grooves 15 and the lands 16 but 17aG and 17aL do not simultaneously exist on both left and right sides of the same place. The pits 17b of zigzag marks 13b formed at the boundaries between the grooves 15 and the lands 16 are so formed as to verge on both central axes of the respective grooves 15 and lands 16 adjacent to each other. At this time, the zigzag marks 13b are formed as a pair of the pits 17b sorted to the right and left from the central axes of the land tracks and the central axes of the groove tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk on which information can be written or rewritten, and more particularly to an optical disk that enables stable tracking control and high-density recording / reproduction.

[0002]

2. Description of the Related Art Generally, in a commercially available recordable optical disk, one of a concave portion (guide groove, generally called a groove) and a convex portion (generally called a land) formed spirally or concentrically. About 0.8 ~
An information recording track is formed at a track pitch of 1.6 μm, and information is recorded in a data area provided on this track. FIG. 5 is a plan view of a general recordable optical disk. The track 2 of the optical disc 1 is formed in a spiral shape (spiral shape), and has a sector structure in which an address area 3 and a data area 4 are paired and periodically divided. In the address area 3, there are address information 3a and tide marks 3b which are formed in advance by the concave and convex pre-pits 7a and 7b, and indicate the address of the succeeding data area 4 and information for detecting the track DC offset. (Illustrated in FIG. 6).

FIGS. 6 and 7 show states of the address area 3 in the case where the data area 4 is formed in the groove 5 and in the case where the data area 4 is formed in the land 6. FIG. 6 is a diagram showing a state of formation of the address information 3a and the puddle mark 3b when the data area 4 is formed in the groove 5. As shown in FIG. 6, the immediately preceding data area (groove)
Subsequent to 4, address information 3a is formed on the center axis of the same track 2 with prepits 7a having the same width as the groove 5,
Subsequently, plein marks 3b are formed on the left and right sides of the center axis of the track 2 to detect tracking DC offset and control tracking by prepits 7b having the same width as the groove 5.

FIG. 7 is a diagram showing a state of formation of the address information 3a and the tider 3b when the data area 4 is formed on the land 6. FIG. As shown in FIG. 7, following the immediately preceding data area 4 formed on the land 6, the same track 2
The pre-pits 8 having a width smaller than the width of the lands 6 on the center axis of
a, address information 3a is formed, followed by a pitting mark 3b on the left and right of the center axis of the track 2 for detecting a track DC offset and controlling tracking by a prepit 8b having a width smaller than the width of the land 6. ing.

[0005] In recent years, since the amount of information has been increased along with the improvement of image quality of video information and the demand for downsizing of recording media has been increasing, it is necessary to improve the recording density of optical disks. For this purpose, for example, Japanese Patent Publication No. 4-276
A method of recording information by forming a recording mark 9 on both the groove 5 and the land 6 as disclosed in Japanese Patent Application Publication No. 10-210 or the like has been proposed. FIG. 8 is an enlarged perspective view of a partially cut-away optical disk medium recorded by this method. This method is generally called land / groove recording. The physical track pitch is the same as the conventional one, so that stable tracking can be maintained, and the information track pitch is reduced by half to about 0.6 to 0.8 μm. Therefore, the density can be doubled as compared with the conventional case. As a method of reducing crosstalk from adjacent information tracks resulting from the information track pitch being reduced to half that of the conventional one, methods such as optimization of groove depth and signal processing are being actively researched and developed.

A method of forming address pits at the boundary between a land track and a groove track and using the information as address information for both land and groove is a DVD-RAM (DVD-RAM).
It is standardized as a Rewritable Disc) BOOK.
In this method, as shown in FIG. 9, address information 13c and address information 13d are arranged while being displaced in the radial direction of the disk. The land track and the groove track are optical disks formed alternately every one rotation. And FIG.
As shown in FIG.
When scanning is performed, the pit 17c and the pit 1 with respect to the laser beam are immediately before the groove 15 and immediately before the land 16.
Since the arrangement with 7d is reversed in the radial direction,
As shown in FIG. 10, the push-pull reproduction signals of the address information 13c and 13d appear with the positive and negative polarities reversed immediately before the groove 15 and immediately before the land 16. This can be used for tracking control as means for determining whether a track for recording and reproducing data is a land or a groove.

[0007]

In the land / groove recording, if address information or the like is formed only on one of the land track and the groove track as in the prior art, the address is recorded and reproduced on the other track. Readout and track DC offset cannot be detected. That is, if the address cannot be read, it becomes impossible to record information on a desired track or sector at an accurate position. The track DC offset appears when a push-pull tracking servo is employed, and occurs due to a lens shift, a disk tilt, or the like. When the track DC offset is present, even if the tracking error signal indicates 0 (zero), the center of the beam is not at the center of the track, which causes a problem in that the recording and reproduction of the information signal is hindered. Was.

When it is considered that the address information and the puddle mark are provided on both the land track and the groove track, the puddle mark 3b of the groove track has the same width as that of the groove 5 as shown in FIG. If formed using a beam, it will protrude to the land 6 side, so it is necessary to form using another beam narrower than the groove 5. However, if another beam is used, it is difficult to completely match the center axis of the puddle mark 3b for detecting the track DC offset with the center axis of the groove 5 for recording information data.
Since the subtle deviation hinders the recording and reproduction of data in and from the groove 5, it has not been possible to provide address information and pleated marks on both the land track and the groove track. Also, a DVD-RAM in which address pits are formed at the boundary between the land track and the groove track, and are used as land / groove address information.
In the method standardized as (DVD-Rewritable Disc) BOOK, since the address pits 17c and 17d are not arranged at the center of the track, the center position of the laser beam does not coincide with the center position of the address pit, so that the best reproduced signal is obtained. There was a problem that could not be obtained.

As described above, although land / groove recording has been proposed in recent years, there has been no optical disk on which good address information and information for tracking control are actually formed for recording and reproducing on both tracks. . Accordingly, the present invention provides a spiral or concentric concave and convex portion formed alternately as a track for each rotation, and an address region and a data region in the concave and convex portions formed alternately. An optical disc formed by alternately forming an address information pre-pit row provided on a center line of the concave track in the address area;
The address information pre-pit row provided on the center line of the convex track and the tracking control pre-pit provided between the concave track and the convex track are arranged without being in phase with each other. Providing an optical disk characterized by the above features, it is possible to reliably read out the address information of each of the land track and the groove track and detect the track offset, thereby achieving stable and accurate tracking control and high density. An object of the present invention is to provide an optical disk that realizes recording and reproduction, and to solve the above problems.

[0010]

As means for attaining the above object, as shown in FIGS. 1 and 2, a concave portion (groove) 15 and a convex portion (land) are formed spirally or concentrically.
16 are alternately formed as tracks for each rotation, and an address area (address information prepit row + tracking control prepit) is provided in the concave track 15 and the convex track 16 formed alternately. Area) and a data area (an area where data is recorded) are alternately formed, and a center line (center axis) G of the concave track 15 is provided in the address area.
C, address information prepit strings (groove address information) 13aG and 17aG provided on
6 of address information pre-pits (land address information) 13aL, 17aL provided on the center line (center axis) LC of No. 6
And the tracking control pre-pits (tread marks) 13b and 17b provided between the concave track 15 and the convex track 16 do not match each other in phase (that is, the groove address information, the land address information and the And an optical disk, wherein the marks are not arranged adjacent to each other). The tracking control pre-pits are composed of a tracking control pre-pit row.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an optical disk according to the present invention, address information is formed on both the center axis of a land track and the center axis of a groove track by using concave and convex prepits.
Subsequent to the address information, a land DC-offset is detected, and a puddle mark represented by a concave pre-pit or a series of concave pre-pits for facilitating land / groove discrimination is formed at the boundary between the land track and the groove track. Address and track DC offset, and land / groove discrimination can be performed in both the channel and the groove.

Here, an embodiment of the optical disk of the present invention will be described with reference to the drawings. 1 and 2 are partial plan views showing a rewritable optical disk which is an embodiment of the optical disk of the present invention. 1 and 2, the width of the groove 15 and the width of the land 16 are each 0.5 to 0.6 μm, and the ratio of the width of the groove 15 to the width of the land 16 is approximately 1: 1.
Address information of groove 15 (groove address information)
Pit 17aG indicating 13aG and pit 1 indicating address information (land address information) 13aL of land 16
7aL has a pit width of 0.5 μm to
The pits are formed on the central axes GC and LC of the land 15 and the groove 16, respectively, with a pit length of about 0.6 μm and a pit length of about 0.4 μm. The respective central axes of the pits 17aG and 17a coincide with the respective central axes GC and LC. And
The pit 17b of the puddle mark 13c for track offset detection and land / groove discrimination formed at the boundary between the land 15 and the groove 16 has a pit width of the groove 15b.
0.5 to 0.6 μm, the same as the width of the pit, and the pit length is 0.4 μm.
m and land 1 and groove 1 adjacent to each other
5 so as to be in contact with both central axes GC and LC.

As described above, the address information 13aG, 13a
Since the pits 17aG and 17aL indicating L are formed on the extension lines of the center axes GC and LC of the land track and the groove track, the address is reliably read regardless of whether recording or reproduction is performed on either the land 16 or the groove 15 track. Can be done.

The puddle mark 13c is connected to the land 16
Are formed as a pair of pits 17c distributed to the left and right from the center axis LC of the track 15 and the center axis GC of the track 15 of the groove 15. Therefore, the pits 17c are adjacent to each other regardless of whether the recording or reproduction is performed on either the land 16 or each track of the groove 15. While sharing the pit 17c between the tracks, the magnitude of the reflected light can be compared in the conventional manner, and the deviation from the track center, that is, the track DC offset can be detected.

The tracks on the lands 16 and the tracks on the grooves 15 are alternately formed for each rotation. As shown in FIG. 11, when the laser beam scans L → M at the center of the tracks, the tracks immediately before and after the grooves 15 are formed. Immediately before the land 16, the arrangement of the pits 17c of the puddle mark 13c with respect to the laser beam is reversed in the radial direction, so that the push-pull reproduction signal of the puddle mark 13c is, as shown in FIG. Immediately before the land 16, the positive and negative polarities appear to be reversed. This can be used for tracking control as means for determining whether a track for recording and reproducing data is a land or a groove.

Next, tracking control of the optical disk recording / reproducing apparatus for recording / reproducing the optical disk of the present embodiment will be briefly described with reference to the configuration diagram shown in FIG. It should be noted that FIG. 2 shows only a portion related to tracking control of the optical disc recording / reproducing apparatus, and other portions are omitted.
Laser light output from the semiconductor laser 31 is converted into parallel light by a coupling lens 32, then supplied to an objective lens 34 via a beam splitter 33, and collected on the optical disk 11. Then, the light reflected by the optical disk 11 is converted into parallel light by the objective lens 34, the direction is changed by the beam splitter 33, and supplied to the condenser lens (detection lens) 35. The converging lens 35 converges the supplied parallel light to a tracking servo photodetector 36.

Photodetector 3 for tracking servo
6 outputs an equal-sized signal from each detector when the beam spot is accurately positioned on the groove or land to be scanned, and outputs a signal when the beam spot is displaced in the tracking direction from the groove or land to be scanned. The signal output from one of the detectors according to the shift direction is output as a larger signal than the other. This output signal is supplied to the differential amplifier 37 and output as a tracking error signal indicating the difference between the input signals. The tracking error signal is supplied to a servo circuit 38 and subjected to a process such as phase compensation, and then supplied to an actuator drive amplifier 39, and the objective lens 34 is provided in accordance with the tracking error signal.
Drive the tracking actuator 40 for driving, thereby performing beam spot tracking control,
Recording and playback of information.

[0018]

As described above, according to the present invention, in the address area, the address information pre-pit row provided on the center line of the concave track (groove track) and the center line of the convex track (land track) are provided. And the tracking control pre-pits provided between the concave track and the convex track are not aligned with each other, that is, the address information pre-pits provided on the concave track and the convex track are not aligned. Are not adjacent to each other, and the address information and the tracking control pre-pits are arranged without being adjacent to each other, so that stable and highly accurate tracking can be performed even in the recording and reproduction on the groove track and the land track. Control becomes possible. Further, since the land / groove recording can be stably performed by the optical disc of the present invention, the amount of information can be increased by high-density recording / reproduction, and the size of the recording medium can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial plan view showing a rewritable optical disk which is an embodiment of the optical disk of the present invention.

FIG. 2 is a partial plan view showing a rewritable optical disk which is an embodiment of the optical disk of the present invention.

FIG. 3 is a configuration diagram for explaining tracking control of the optical disk recording / reproducing apparatus.

FIG. 4 is a diagram for explaining timing signals (data / address signals) in a data area and an address area.

FIG. 5 is a plan view showing a general recordable optical disc.

FIG. 6 is a plan view showing a state of an address area in a general groove recording method.

FIG. 7 is a plan view showing a state of an address area in a general land recording method.

FIG. 8 is a partially cutaway enlarged perspective view showing an optical disk medium of land & groove recording.

FIG. 9 is a plan view showing a state of an address area in a conventional land & groove recording method.

FIG. 10 is a diagram for explaining a land / groove discrimination reproduction signal in a conventional land & groove recording method.

FIG. 11 is a diagram illustrating a land / groove discrimination reproduction signal in the optical disc of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Track 3 Address area 3a, 13a Address information 3b, 13b Tidori mark 4, 14 Data area 5, 15 Groove (concave, concave track) 6, 16 Land (convex, convex track) 7a, 7b, 8a, 8b Pre-pit 9 Record mark 13aG, 17aG Groove address information (address information pre-pit string) 13aL, 17aL Land address information (land information pre-pit string) 13b, 17b Pinch mark (tracking control pre-pit) 17a, 17b Pit (pre-pit) GC, LC Center axis (center line)

Claims (2)

[Claims] 1. A spiral or concentric concave and convex portion are alternately formed as tracks for each rotation, and an address region and a data region are alternately formed in the concave and convex tracks. An optical disc formed by alternately forming, in the address area, an address information pre-pit row provided on a center line of the concave track, and an address information pre-pit row provided on a center line of the convex track, An optical disc, wherein tracking control pre-pits provided between the concave track and the convex track are arranged without being in phase with each other. 2. The tracking control pre-pit,
2. The optical disk according to claim 1, wherein the optical disk comprises a tracking control pre-pit row.