JPH0917033A - Optical disk and its signal reproducing method as well as optical disk device - Google Patents

Abstract

PURPOSE: To make it possible to increase the capacity of an optical disk by forming rugged pits as information in both of groove parts (recessed parts) and land parts (projecting parts) and decreasing crosstalks. CONSTITUTION: Both of the recessed parts 103 and projecting parts 104 of the grooves 101 for laser beam tracking are formed as recording tracks. The preformats 102 disposed on the optical disk are formed in the recessed parts 102 of the grooves for tracking and are constituted as the convexo-concave pits larger than the width of the recessed parts. The preformats 102 formed in the recessed parts are reproduced in the case the recessed parts 103 of the optical disk are subjected to recording and reproducing. The preformat signals of the recessed parts of the one zone and the preformat signals of the recessed parts of the other zone are reproduced in the case the projecting parts 104 are subjected to recording and reproducing. The crosstalk components from both are considerably large as the preformats are formed to protrude largely. The reproduction of such components is sufficiently possible and the discrimination of the tracks and sectors of the projecting parts is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc which is an optical information recording medium for recording / reproducing information by irradiating a laser beam, and more particularly to an optical disc, a signal reproducing method for the optical disc and an optical disc device.

[0002]

2. Description of the Related Art An optical disk recording system using a laser beam is capable of large-capacity recording and non-contact high-speed access.
Optical disks are classified into a read-only type known as a compact disk and a laser disk, a write-once type that can be recorded by a user, and a rewritable type that can be repeatedly recorded by a user. Among them, the write-once type and rewritable type optical disks are used as external memory of computers or as document / image files.

In the signal reproduction on the currently used optical disc, the optical disc is irradiated with laser light,
A reproduction signal is detected from a laser beam that has been modulated and reflected by the optical disc. For example, in a reproduction-only type, a reproduction signal is extracted by using a change in the amount of reflected light from pits having irregularities formed on a disk. In the write-once type, a small pit formed by laser irradiation or a change in the amount of reflected light accompanying a phase change is used for reproduction. In a rewritable magneto-optical disk, the magnetization state of the recording film is read out as a change in the plane of polarization using the magneto-optical effect of the recording film. As with the write-once type, the other rewritable type, a phase change optical disk, uses the change in the amount of reflected light due to the phase change for reproduction.

In such an optical disk technology, 1.2 formed on a transparent resin or glass substrate has been conventionally used.
A laser beam focused along a spiral groove having a pitch of μm to 1.6 μm is tracked to record information C
The SS servo system is adopted. In this method, one track is divided into several tens of sectors, and a pre-format concave-convex pit indicating the track address of the sector is recorded at the beginning of each sector. The track used for recording uses a so-called groove recording or land recording method in which recording is performed in either a concave portion (groove) or a convex portion (land) of a groove. To form.

In order to improve the recording density of an optical disc, a land / groove recording method in which recording is performed not only on one of the concave and convex portions of a track but on both the convex and concave portions of the track is promising and has already been proposed. K. Kayanum
Its effectiveness was reported by a. (SPIE
Proceeding Vol. 1316, PP35)
However, if the track pitch is made narrower than the current level and further preformatted uneven pits are to be formed in both the land and groove, the width of the concave and convex parts is narrow, so good unevenness is formed in both parts. There is a problem that it is very difficult to form pits and crosstalk between preformats occurs.

For this reason, conventionally, as a measure for reducing crosstalk between preformats in a narrow track, Japanese Patent Laid-Open No. 1-286122 proposes to alternately shift the arrangement of adjacent preformats. Further, as a preformat forming method for a narrow track, Japanese Patent Laid-Open No. 5-218471 and Japanese Patent Laid-Open No. 5-166739 propose a method of forming a preformat that extends beyond the groove width.

[0007]

However, the above-mentioned measures for reducing crosstalk are limited to the case where only one of the concave portion and the convex portion is used, and uneven pits are formed in both the concave portion and the convex portion. If it does, it cannot be applied as is. Similarly, the above-described preformat forming method is also limited to the case where recording is performed only on one of the concave portion and the convex portion, and cannot satisfy the above-mentioned requirements.

[0008]

It is an object of the present invention to form an uneven pit in both a groove portion and a land portion, and to reduce crosstalk to realize a large capacity optical disc and a signal reproduction. A method and an optical disk device are provided.

[0009]

The optical disk of the present invention comprises:
Both the concave and convex portions of the laser light tracking groove are used as recording tracks, and the pre-format provided on the optical disc is formed in the concave portion of the tracking groove, and this pre-format is an uneven pit larger than the width of the tracking groove. Is characterized in that. Further, the optical disc of the present invention uses both the concave and convex portions of the laser light tracking groove as recording tracks, and the preformat provided on the optical disc is a shape in which the concave portion of the tracking groove is meandering in the radial direction. And

In this case, the pre-format forming zone is divided into two zones in the direction of forming the tracking groove for each of a plurality of sectors formed on the optical disk, and the pre-format is alternately arranged every other track of the tracking groove.
It is preferably formed in one zone.

Further, the signal reproducing method of the present invention reproduces the preformat signal of the preformat forming zone when reproducing the preformat signal of the concave portion provided on the optical disk, and reproduces the preformat signal of the convex portion when reproducing the preformat signal of the convex portion. It is characterized in that the pre-format is discriminated by reproducing the crosstalk pre-format signal from the recessed pre-format forming zone of the two zones in which the format is formed.

Further, in the optical disk device of the present invention, at least the preformat signal reproducing means of the optical disk concave portion and the convex portion from the crosstalk preformat reproduction signal from the concave preformat forming zone of the two zones in which the preformat is formed. The present invention is characterized by having a convex portion preformat information determining means for determining preformat information.

[0013]

When recording / reproducing to / from the concave portion of the optical disk, it is sufficient to reproduce the preformat formed in the concave portion. The preformat is formed in only one zone. With respect to the above, since the formed zones are different, it is possible to satisfactorily reproduce without receiving interference from the concave portions on both sides.

On the other hand, when recording / reproducing is performed on the convex portion, the preformat signal of the concave portion of one zone and the preformat signal of the concave portion of the other zone are reproduced. The crosstalk components from both are considerably large because the preformat is formed so as to largely extend, and it is sufficiently possible to reproduce them. If the crosstalk component from both of these zones is reproduced and further subjected to signal processing, it can be used as a preformat and the track and sector of the convex portion can be discriminated.

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a detailed view of a part of the optical disc according to the first embodiment of the present invention, showing a pre-format formed in a tracking groove 101 provided in the optical disc 10. In the figure, the left and right sides of the figure are the radial direction of the optical disc, and the concave portions 103 and the convex portions 104 of the plurality of tracking grooves 101 are alternately arranged in this portion of the optical disc. In this embodiment, the pre-format concave / convex pit 102 is formed into a circular shape, an elliptical shape, or an oval shape, and the length of the optical disc in the radial direction is made larger than the width of the groove 101 for laser light tracking, and the center of the groove 101 is formed. The concavo-convex pits are formed so that their centers coincide with each other. As a result, a part of the outer peripheral portion of the preformat concave-convex pit 102 is formed so as to extend to the portion of the convex portion 104 adjacent to the concave portion 103 of the groove 101.

Further, the preformat forming zone is divided into two zones in the lengthwise direction of the groove, the preformat 102 is provided only for one of the recesses 103, and the adjacent recesses 103 are The preformats are alternately formed so that the preformats 102 are present in different zones.

FIG. 2 is a detailed view of a part of the optical disc according to the second embodiment of the present invention, showing the same part as FIG. In this embodiment, the preformat 202 is a so-called wobbling type preformat 202 in which the concave portion 203 of the tracking groove 201 is meandered in the radial direction toward the convex portions 204 on both sides while keeping the groove width constant.
Is formed as. The meandering frequency is set sufficiently higher than the tracking band. Therefore, when this part is reproduced, as will be described later, the meandering cycle is faster than tracking tracking, so the fluctuation component of the groove is detected as a change in reproduction light amount. . Also in this embodiment, the preformatted area 202 is divided into two zones in the length direction of the groove, and only one of the recesses 203 of each tracking groove is provided, and the adjacent recess is provided in each zone. The preformats are formed so that they are alternately formed.

The preformats shown in FIGS. 1 and 2 are usually formed on a transparent substrate. A magneto-optical recording medium or a phase change recording medium is formed and used on this substrate. In the magneto-optical recording medium, as shown in FIG. 4, at least a first dielectric layer 402, a magneto-optical recording layer 403, and a second dielectric layer 404 are formed on a disk substrate 401. Also, as shown in FIG.
On the disk substrate 501, at least the first dielectric layer 5
02, a magneto-optical recording layer 503, a second dielectric layer 504, and a metal reflection layer 505 are sequentially formed.

The magneto-optical recording films 403 and 503 are mainly composed of rare earth transition metal alloys such as TbFe, TbFeCo, and
GdTbFeCo, DyTbFeCo, GdDyTbF
eCo, DyCoTbCo, or the like is used. Dielectric 40
1,403, 501 and 503 are SiN, SiO,
AlN, TaO, etc. are used. As the metal reflection layer 505, Al, AlTi, or the like is used.

In the phase change recording medium, as shown in FIG. 6, at least the first dielectric layer 602, the phase change recording layer 603, and the second dielectric layer 60 are formed on the disk substrate 601.
4 is sequentially formed, or as shown in FIG. 7, at least a first dielectric layer 702, a phase change recording layer 703, a second dielectric layer 704, on a disk substrate 701.
A structure in which a reflective layer 705 is sequentially formed, and further, as shown in FIG. 8, at least a first dielectric layer 802, a phase change recording layer 803, a second dielectric layer 804, and a reflection layer are formed on a disk substrate 801. A structure in which the layer 805 and the third dielectric layer 806 are sequentially formed is adopted.

GeSbTe and Ge, which are mainly chalcogenide materials, are used for the phase change recording films 603, 703 and 803.
Te, InSbTe, or the like is used. Dielectric 601,60
ZnS-SiO _2, SiN as 3,701,703,801,803,806, using SiO, AlN, those mainly composed of such TaO. Reflective layers 705 and 80
As Al, Al, AlTi, Si, Ge or the like is mainly used.

Next, a method of reproducing a preformatted signal from the optical disk according to the present invention will be described. The present invention employs a so-called land / groove recording method in which both concave and convex portions of the optical disk are used for recording and reproduction, and both concave and convex portions of the laser beam tracking groove are used as recording tracks. When reproducing the preformat signal from the recess, it is sufficient to reproduce the preformat signal in the preformat formation zone as it is, and the conventional signal reproduction method can be used as it is, and the change in the reflected light amount from the preformat can be reproduced by the photodetector. Good.

On the other hand, at the time of reproducing the preformat signal from the convex portion, the crosstalk component from the two-zone concave preformat forming zone in which the preformat is formed is picked up. First, the preformatted signal from zone 1 is reproduced, and then the preformatted signal from zone 2 is reproduced.

For example, when information is recorded / reproduced in / from the concave portion 103 of the optical disc 10 of the first embodiment shown in FIG. 1, the preformat 102 formed in the concave portion 103 may be reproduced. Since the preformat is formed in only one zone and the preformats of the recesses 103 on both sides are different, the preformat can be reproduced well without interference from the recesses on both sides.

On the other hand, when recording and reproducing a portion of a certain convex portion 104, the preformat signal from the concave portion 103 of zone 1 and the preformat signal from the concave portion 103 of zone 2 in FIG. 1 are reproduced. The crosstalk component from both is considerably large because the preformat 102 is formed so as to largely protrude. Therefore, it is sufficiently possible to reproduce this. If the crosstalk component from both zones is reproduced and further processed as a signal, it can be used as a preformat and the track and sector of the convex portion can be discriminated.

When information is recorded / reproduced in / from any recess 203 of the optical disc of the second embodiment shown in FIG. 2, the meandering preformat 202 formed in the recess may be reproduced. This pre-format 202 is also formed in only one of the zones, and the pre-formats of the recesses 203 on both sides are different from each other in the formation zone, so that good reproduction can be performed without interference from the zones.

On the other hand, when recording / reproducing an arbitrary convex portion 204, the preformat signal from the concave portion 203 of zone 1 and the preformat signal from the concave portion 203 of zone 2 are reproduced. The crosstalk components from both are quite large because the preformat is formed to meander. Therefore, it is sufficiently possible to reproduce this. If the crosstalk components from both zones are reproduced and further subjected to signal processing, it can be used as a preformat and the track and sector of the convex portion 204 can be discriminated.

FIG. 3 is a block diagram showing an example of the optical disk device for performing the recording / reproducing described above. Optical head 3 for irradiating the optical disc 10 with light and receiving the reflected light
01, and a signal regenerative amplifier 30 for amplifying the received signal light
2, and a signal switcher 30 for switching the signal between the concave portion and the convex portion
3, concave part preformat reproducing means 304 and convex part preformat information judging means 305 for reproducing respective preformats based on the switched concave and convex signals. In particular, the convex portion preformat information determining unit 305 has a function of determining the convex portion preformat information from the crosstalk preformat reproduction signal from the two-zone concave portion preformat forming zone in which the preformat is formed.

This convex portion preformat information judging means 3
Here, 05 temporarily stores the preformat reproduction signal from the zone 1 and the preformat reproduction signal from the zone 2 in the memory, and compares them to calculate the track and sector of the convex portion. For example, when the track and sector number information from zone 1 is the 12th sector of the 04435th track and the track and sector number information from zone 2 is the 12th sector of the 04437th track, the track and sector of this convex portion are It is sufficient to configure the logic circuit of the judging means so as to judge that it is the 12th sector of the 04436th track. That is, the desired convex track number is (zone 1 track number + zone 2 track number) / 2, and the desired convex sector number is (zone 1 sector number = zone 2 sector number)
And

[0030]

As described above, according to the present invention, the preformat provided on the optical disk is formed in the concave portion of the tracking groove, and the preformat is formed as an uneven pit larger than the width of the tracking groove. Therefore, the groove / land recording preformat corresponding to the narrow track recording can be realized, and the large capacity recording of the optical disk can be achieved.

Further, according to the present invention, since the preformat provided on the optical disk is formed in a shape in which the concave portion of the tracking groove is meandered in the radial direction, the groove / land recording preformat corresponding to the narrow track recording is similarly provided. Can be realized, and large-capacity recording on an optical disk can be achieved.

In particular, in the present invention, each of a plurality of sectors formed on the optical disk is divided into two zones in the extension direction of the tracking groove, and the preformat is one of the tracking grooves.
By forming two zones alternately for every track,
The preformat formed in the concave portion can also be determined as the preformat of the convex portion, and large-capacity recording of the optical disc compatible with narrow track recording can be achieved.

Further, in the signal reproducing method of the present invention, particularly when reproducing the preformatted signal of the convex portion, the crosstalk preformatted signal is reproduced from the concave preformat forming zone of the two zones in which the preformat is formed. , It becomes possible to determine the pre-format.

Further, in the optical disk device of the present invention, the convex part preformat information judgment for judging the convex part preformat information from the crosstalk preformat reproduction signal from the concave part preformat forming zone of the two zones in which the preformat is formed is carried out. The provision of the means makes it possible to determine the preformat of the convex portion.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part of an optical disc according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of an optical disc according to a second embodiment of the present invention.

FIG. 3 is a block configuration diagram of an optical disk device according to the present invention.

FIG. 4 is a sectional view of an optical disk according to the present invention.

FIG. 5 is a cross-sectional view of another optical disc according to the present invention.

FIG. 6 is a cross-sectional view of another optical disc according to the present invention.

FIG. 7 is a cross-sectional view of another optical disc according to the present invention.

FIG. 8 is a sectional view of another optical disk according to the present invention.

[Explanation of symbols]

 10 optical disc 101 tracking groove 102 preformat 103 concave portion 104 convex portion 201 tracking groove 202 preformat 203 concave portion 204 convex portion Z1 zone 1 Z2 zone 2 301 optical head 304 concave portion preformat reproducing means 305 convex portion preformat information judging means

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G11B 11/10 511 9075-5D G11B 11/10 511D 586 9296-5D 586G 20/12 102 9295-5D 20/12 102

Claims (5)

[Claims] 1. An optical disc in which information is recorded / reproduced / erased by using a laser beam, and both concave and convex portions of a laser beam tracking groove are used as recording tracks, and a preformat provided on the optical disc is the tracking groove. An optical disc, characterized in that the pre-format is concave and convex pits formed in the concave portion of which are larger than the width of the tracking groove. 2. In an optical disc in which information is recorded / reproduced / erased by using a laser beam, and both concave and convex portions of a laser beam tracking groove are used as recording tracks, a preformat provided on the optical disc is the tracking groove. An optical disk having a shape in which the concave portion of the optical disk meanders in the radial direction. 3. A pre-format forming zone is divided into two zones in the direction of forming a tracking groove for each of a plurality of sectors formed on an optical disk, and pre-formatting is performed alternately every other track of the tracking groove. The optical disc according to claim 1, which is formed in the format zone. 4. A concave portion and a convex portion of a groove for laser light tracking formed on an optical disk are used as recording tracks, and at the time of reproducing a preformat signal from the concave portion, a preformat signal of a preformat formation zone is reproduced from the convex portion. During pre-format signal reproduction, the optical disc pre-format signal reproduction is characterized in that the pre-format is discriminated by reproducing the crosstalk pre-format signal from the concave pre-format forming zone of the two zones in which the pre-format is formed. Method. 5. The convex preformat information is determined from at least the preformat signal reproducing means from the concave portion of the optical disc and the crosstalk preformat reproduced signal from the concave preformat forming zone of the two zones in which the preformat is formed. An optical disk device having a convex portion preformat information judging means.