JP2002197725A - Recording medium, master disk of recording medium and manufacturing method for recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium wherein distinction between a pit track and a groove track and optical detection of the pit by an optical pickup and the like can be reliably performed and confirmed to the standard of the recording and reproducing characteristics set under the specification of the MD-data2 and the like, to provide a master disk of the recording medium and to provide a manufacturing method for the recording medium. SOLUTION: A pit 201 and grooves 202a and 202b are formed so as to form separate continuous tracks respectively on the surface of a substrate. The information carried by the pit 201 and the information carried by the grooves 202a and 202b are respectively set so that they can be continuously read along the respective tracks. The ratio of a pit track pitch 301 to the track pitch between the grooves 202a and 202b, that is a groove track pitch 302, is specified to be >1.00 and <=1.087.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium in which pits and grooves which can be detected optically or magneto-optically form separate spiral tracks, and a method of manufacturing the same. the method of manufacturing a recording medium the master as well as a recording medium used.

[0002]

2. Description of the Related Art An optical recording medium is mounted on a rotary table of a recording / reproducing apparatus and performs recording and reproduction (reading) based on reflected light of a laser beam applied to a signal recording layer of a substrate. It is set as follows. The optical recording media, read-only CD-ROM (Compact Disc-Read
An optical disk such as an Only Memory, a magneto-optical disk or a phase-change optical disk in which a signal can be rewritten are known.

For example, in a recording medium such as an MD (Mini Disc), as shown in an example in FIG. 9, a groove 700 for recording various information as recording contents and a type and recording capacity of the disc itself are provided. Pit 800 for recording information
Bets has been formed by making full use of precision processing technology of submicron order accuracy. The groove 700 is formed in a groove shape along the circumferential direction of the disk, and is formed in a wobble pattern meandering at a predetermined amplitude in the radial direction of the disk. On the other hand, the pit 800
It is formed in an oval pattern such as a so-called soccer stadium shape. In the case of the pits 800, one track is formed by arranging a large number of pits along the circumferential direction of the disk.

[0004] More specifically, the groove 700 is formed so that various data can be written / read in a data recording area. TOC as the information of the disc itself
(Table Of Contents) information is written in the pit 800 in the lead-in track area. Therefore, the conventional MD
In the optical disk as described above, the area where the pit 800 is formed and the area where the groove 700 is formed are separated concentrically, but they constitute one continuous spiral track.

Generally, the width of the groove 700 is 80 pits.
Although it is set wider than the width of 0, it is intended that the recording / reading of information can be performed more accurately by increasing the width of the groove 700 for recording data. It was done. That is, when data is recorded in the narrow groove 700, noise increases and the S / N ratio decreases. Alternatively, data may be recorded on a land 750 wider than the groove 700. However, since the wobble phases of the grooves 700 adjacent in the radial direction of the disk do not match, the width of the land 750 is reduced. It constantly changes and the fluctuation of the reproduction signal becomes large, which is not suitable for practical use. Therefore, it is desirable to record data in the groove 700 having a wider width.

In the conventional MD, the recording / reproducing time is generally set to 60 minutes or 74 minutes, but in recent years, a longer time of 80 minutes has been proposed. More specifically, the lead-in track area in which pits carrying TOC information and the like are formed based on a unified standard or the like has a radius of r.
= Area of from 14.5mm to 16.0 mm, the data recording area which grooves are formed for data recording and reproducing target is region and each set from a radius r = 16.0 mm to 30.5 mm. The recording / reproducing time is determined by the recording / reproducing speed (linear velocity) of the groove and the track pitch. According to the MD standard, the linear velocity is from 1.20 m / s to 1.40 m / s and the track pitch is 1. 60
± 0.10 μm.

By the way, in addition to such an MD having one spirally continuous track, a simple spiral straight groove and a wobbled plane which is not connected to the straight groove but is separate and separate from the MD. A format called MD Data2 including a wobbling groove formed in a meandering pattern and a pit track not connected to the groove track has been proposed.

In this MD Data2, a land between a straight groove and a wobbling groove forming a double spiral is a recording area. The dimensions of the standard, straight groove and the track pitch between the wobbling groove center (Track Pitch) 0.95
± 0.03μm, double spiral 1 cycle width (Track
Peroid) is 1.9 ± 0.05 .mu.m, a track pitch of pits are defined as 0.95 ± 0.05 .mu.m, which is assumed to machining accuracy of submicron order is required.

[0009]

However, the MD
In the recording medium of Data2 format, the pit width is widened to 0.43 μm, so that the RC (Radial Constant) is used.
The present inventors have confirmed through various experiments and analysis thereof that problems such as reduction of ant) and deterioration of skew characteristics in the disk radial direction occur.

That is, since the pit track pitch is defined as 0.95 ± 0.05 in the MD Data2 standard, if the track pitch is set to, for example, 0.93 and the pit width is set to 0.43 μm, The ends of the pits adjacent in the disk radial direction are in a state of being extremely close to each other, and characteristics such as RC and skew deteriorate.

[0011] In addition, similar to the general tendency, MD D
It is desired that the recording capacity of the ata2 recording medium be further improved. However, if the track pitch is narrowed to meet the demand, the above-described problem occurs. Or it becomes impossible.

Namely, the conventional MD or the like optical or magneto-optical; In (MO Magnet Optical) disk, basically, is formed so as to form a single spiral track of track and a groove of the pit are consecutive The track pitch was set the same for the pits and grooves.
For this reason, various techniques for maintaining a constant track pitch as accurately as possible have been devised, but changing the track pitch of pits and grooves has not been considered. Similarly, on a recording medium of MD Data2,
The pits and grooves have the same track pitch. If the groove track pitch is narrowed to improve the recording capacity in the data recording area, the pit track pitch will also be narrowed, and signals such as RC and skew in the pits will be reduced. The characteristics deteriorate. On the other hand, a pit width as large as 0.43 μm is required in order not to lower the unsymmetry of the pit signal. However, if the pit width is increased in such a manner, the pit track pitch is correspondingly increased. Inevitably, the track pitch of the groove was also widened accordingly, which was against the increase in the capacity of the data recording area.

The present invention has been made in view of such a problem, and an object of the present invention is to conform to recording / reproducing characteristics standards such as RC and skew in pits, which are defined in the MD standard such as the MD Data2 format. Is possible,
And to provide a master disk and a method for their preparation is used for the data recording area is to produce as a large capacity recording medium and it combines both qualities.

[0014]

According to the present invention, a recording medium, a recording medium master, and a method of manufacturing a recording medium are formed by forming pits and grooves on a disk-shaped substrate surface so as to form separate continuous tracks. , The information carried by the pits or grooves is set to be continuously readable along each track, and the ratio of the pit track pitch to the groove track pitch is set to 1.
It is set to be more than 00 to 1.087 or less.

According to another recording medium, a recording medium master and a method for manufacturing a recording medium according to the present invention, pits and grooves form separate continuous tracks on the surface of a disk-shaped substrate, and wavelengths are formed along the tracks. 0.655 ±
A 0.01 μm laser is irradiated by an optical system having an NA of 0.52 ± 0.01 so that information carried by the pits and the grooves is set to be continuously readable, and the track pitch of the pits relative to the track pitch of the grooves is set. The ratio is 1.
It is set to be more than 00 to 1.087 or less.

In the recording medium, the recording medium master and the method of manufacturing the recording medium according to the present invention, or the other recording medium, recording medium master and the manufacturing method of the recording medium according to the present invention, good RC and skew can be obtained from the pit-formed area. In order to achieve both the reading of the pit signal with the characteristic and the achievement of a large capacity of the region in which the groove is formed, the ratio of the pit track pitch to the groove track pitch should be more than 1.00 to 1.087. Set as follows. As described above, in the recording medium according to the present invention, the ratio of the track pitch of the groove to the track pitch of the pits is set to be more than 1.00 to 1.087 or less. This means that the pitch is not constant, and the pitch is changed between the groove and the pit.

The present invention is particularly suitable for a recording medium conforming to the MD Data 2 standard. However, it is needless to say that the present invention is not limited to this.

[0018]

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

[0019] Figure 1 illustrates a schematic structure of an optical recording apparatus used in the process of manufacturing the master disk recording medium according to an embodiment of the present invention. Note that the recording medium or the recording medium master according to the present embodiment is embodied by a method of exposing a pattern of pits or grooves by this optical recording device, a method of manufacturing a recording medium including the same, and the like. Hereinafter, they will be described together.

The recording medium according to the present embodiment is an MD Data2 as shown in FIG. 2, and includes a pit track composed of an array of pits 201 in a lead-in track area of an inner peripheral portion and an outer peripheral side thereof. In the data recording area, a groove track composed of the groove 202a of the straight pattern and the groove 202b of the wobble pattern are formed on the substrate surface without being connected to each other as spiral tracks.

Among these tracks, the pit track is a single track, and the groove track is a double track of the groove 202a and the groove 202b. On the substrate surface, for example, a radius r = 14.
The area of 5 to 16.0 mm is the lead-in track area,
An area of r = 16.0 to 30.5 mm is allocated to the data recording area. The distance between the center of the adjacent groove 202a and the center of the groove 202b is called a groove track pitch 302.

The width of the pit 201 in the disk radial direction is
In order to secure a push-pull signal (servo signal) amount that conforms to the recording / reproducing characteristic standard such as RC and skew in the pit, for example, MDD such as 0.43 μm is used.
The width is set to be wider than the width of the groove 202a or the groove 202b corresponding to the standard of data2. The width of the groove 202a or the groove 202b in the disk radial direction is set to, for example, 0.28 μm.

The groove 202 and the pit 201 are set at the same depth. However, it goes without saying that they are not necessarily limited to the same depth.

The ratio between the pit track pitch 301 and the groove track pitch 302 is more than 1.00 to 1.0.
It is set to be a value of 8 or less. When the recording medium is MD Data2, the absolute value of the track pitch between the groove 202a and the groove 202b is desirably a value less than 0.95 μm, such as 0.92 μm. This is because by reducing the groove track pitch 302 formed in the data recording area, it is possible to obtain a large capacity capable of recording and reproducing for a longer time than a general MD.

However, the present invention is not limited to this, and it goes without saying that a wide track pitch of 0.95 μm or more may be used unless recording / reproducing is performed for a long time. On the other hand, the pit track pitch 301, for example, when the groove track pitch 302 is 0.92μm 0.95
μm, or when the groove track pitch 302 is 0.95 μm, the pit track pitch 301
Can be set to, for example, 0.98 μm.
Alternatively, the groove track pitch 302 is set to 0.92 μ
m, and the pit track pitch 301 can be 0.98 μm. At this time, the ratio between the two track pitches is 0.950 μm / 0.92 μm, respectively.
= 1.033, 0.98 μm / 0.95 μm = 1.03
2, 0.98 μm / 0.92 μm = 1.065, and both values are in the range of more than 1.00 to 1.087 or less.

With such a setting, it is possible to further improve the data recording capacity as a magnetic recording medium while enabling reading / writing by a general recording / reproducing apparatus, and to optically detect the pit 201. It can be assured. However, it goes without saying that the combination of the value of the pit track pitch 301 and the value of the groove track pitch 302 and their ratio are not limited to only the above-described combinations.

In the method for manufacturing a recording medium according to the present embodiment, a step of manufacturing a glass master of a recording medium, a step of manufacturing a stamper using the same, and a step of manufacturing a recording medium using the same are described below. In particular, the following description focuses on the technology relating to the formation of the pits 201 and the grooves 202a and 202b.

The optical recording device includes a laser light source 1, an electro-optic modulator (EOM) 2,
Automatic light amount controller 3, photodetector 4, analyzer 5, beam splitters 6a, 6b, modulation optical systems 7a, 7b, λ
/ 2 polarizing plate 8, transmission / reflection mirrors 9a and 9b, moving optical table 10, turntable 12 on which glass master 11 is placed, spindle servo 13, voltage frequency controller 1
4 and a drive circuit 15 are provided as main parts thereof. A master for a recording medium is manufactured by the following general configuration and operation of the optical recording apparatus, and further, MD Data 2 according to the present embodiment can be manufactured using the master.

The laser light source 1 oscillates, for example, a Kr laser beam having a wavelength λ = 413 nm as a light source for exposing a resist formed on the surface of the glass master 11. However, it goes without saying that the light source for exposure is not particularly limited to such a laser light source.

Laser light 2 emitted from laser light source 21
0 is first modulated by the electro-optic modulator 2, and furthermore, for example, a half goes straight with a parallel beam and passes through the transmission / reflection mirror 6.
a, 6b and arrives at the photodetector 4. The photodetector 4 detects the amount of the received laser light. The photodetector 4 automatic light quantity control device 3 a modulation in the electro-optical modulator 2 based on the detected amount of light is feedback-controlled, the light quantity of the laser beam output from the electro-optical modulator 2 to be constant.

On the other hand, the laser beams reflected by the transmission / reflection mirrors 6a and 6b and turned at substantially right angles and divided into two parallel beams of s-polarized light are modulated optical systems 7a and 7a, respectively.
After that, the direction is further changed by the reflection mirrors 9a and 9b, and the light is guided to the movable optical table 10.

[0032] In this case, more specifically, the modulation optical system 7
The laser light that passes through the signal processing circuit 1
AOM (Acoustic Optical Modulator) 70a is controlled based on a control signal and a data signal input via the 07a so that the moving optical table 10 can expose a straight groove pattern or a pit pattern. Is done. On the other hand, the modulation optical system 7
The laser beam that passes through b is transmitted by the AOM 70b
The moving optical table 10 is controlled to have a constant intensity so that the wobbling groove pattern can be exposed.

Then, the laser beam 21a emitted from the AOM 70a passes through a λ / 2 polarizing plate and passes through a reflection mirror 9a.
Optical table 1
It is guided to the polarization beam splitter 102 within 0. On the other hand, the laser beam 21b output from the AOM 70b
Is reflected by the reflection mirror 9b and changes its direction, and the AOD (Acoustic Optical Deflecto) in the movable optical table 10 is changed.
r; acousto-optic deflector) is guided to 101.

As signals for exposing the pattern of the pit 201, 1 to 7 modulation correction signals are used.
A constant level DC (for example, 1 V) signal can be used as a signal for exposing the patterns of the grooves 202a and 202b. The lens systems L11 and L12 are disposed before and after the AOM 70a, and the lens systems L21 and L22 are disposed before and after the AOM 70b, respectively, to collect the incident laser light and convert the emitted laser light into a parallel beam. It is desirable to do so. AOM70a, 7
As an acousto-optic element (not shown) used for Ob, tellurium oxide (TeO2) is preferable.

The moving optical table 10 has an AOD 101,
It includes a polarizing beam splitter 102, a driving circuit 103, reflection mirrors 104a and 104b, a beam magnifying lens 105, and an objective lens 106.

The laser beam 21a incident on the moving optical table 10 passes through the polarizing beam splitter 102, passes through the beam expanding lens 105, is reflected by the reflecting mirror 104a and changes its direction. The light is focused on the surface of the glass master 11. On the other hand, the laser beam 21b which come incident exposure pattern is further optically deflected by AOD101 way wobbled, reflecting mirrors 104b and the polarization beam splitter 1
The light is successively reflected by the laser beam 02 and is condensed on the surface of the glass master 11 by the objective lens 106 via the beam magnifying lens 105 and the reflection mirror 104a. Note that the focal length of the magnifying lens L3 may be, for example, 80 mm, and the numerical aperture (NA) of the objective lens may be, for example, 0.9.

Here, in the moving optical table 10, the direction of the laser beam 21a is changed by the reflecting mirror 104a. At this time, no modulation or the like is performed, and the laser beam 21a position is focused into a spot shape on the surface moves. On the other hand, A
The OD 101 is composed of one acousto-optic element 111 and wedge prisms 112a, 112 arranged before and after the acousto-optic element 111.
b, which are arranged such that the lattice plane of the acousto-optic element 111 and the wedge prisms 112a, 112b satisfy the Bragg diffraction condition and do not change the horizontal height of the optical axis. Acousto-optic element 111
As it can be preferably used tellurium oxide (TeO2). The AOD 101 is controlled by the drive circuit 103.

The driving circuit 103 is, for example, 84.672.
center frequency 224 based on the address information signal of kHz.
A control signal formed by FM-modulating a high-frequency signal of MHz is output to the AOD 101. By the control signal, A
OD101 is controlled to change the Bragg diffraction angle,
The wobbling that carries the address information is generated in the laser beam 21b. The two beam spots of the laser beam 21a and the laser beam 21b are condensed on the glass master 11 while being controlled such that the pitch between their center lines is constant at a value such as 0.92 μm. You.

Since the predetermined inner peripheral area on the surface of the glass master 11 is an area allocated to the lead-in track area, the modulation by the modulation optical system 7a is controlled in this area to control the light of the laser beam 21a. Pattern exposure of the pit 201 is performed by a pulse. The pit track pitch 301 at this time is, for example, 0.95 μm or 0.95 μm.
The pitch is set to be larger than the groove track pitch 302, such as 8 μm.

As described above, while changing the pitch between the track of the pit 201 and the tracks of the grooves 202a and 202b, the laser beam is formed so that the pit track and the two groove tracks are formed in separate spiral patterns without being connected to each other. The resist on the glass master 11 is irradiated with the beam 21a or the laser beam 21b to form desired pits 201 and latent images of the grooves 202a and 202b.

Subsequently, the glass master 11 is subjected to a development process to dissolve the exposed portion of the resist and to perform development.
More specifically, the undeveloped glass master 11 is placed on a turntable of a developing machine (not shown), and a developer is dropped on the surface of the glass master 11 while rotating the turntable to develop a resist. , Groove 202
The glass master 11 obtained by patterning a and 202b can be obtained.

Subsequently, a conductor layer of a nickel (Ni) thin film is formed on the concave / convex pattern of the resist on the glass master disk 11 by using an electroless plating apparatus (not shown). The conductor layer is attached to an electroforming apparatus (not shown) the glass master 11 formed, to form a nickel plating layer on the conductive layer by electroplating.

Subsequently, the nickel plating layer was peeled off from the glass master 11 with a cutter or a peeling squeegee.
Further, the resist remaining on the surface on which the nickel plating layer has been formed is washed with a solvent such as acetone to obtain a stamper (not shown).

By using the stamper, a fine pattern of pits 201 and grooves 202a and 202b corresponding to signal patterns is transferred onto the surface of a substrate 43 made of transparent plastics such as PC (polycarbonate). .

Then, a dielectric layer 4 made of silicon nitride (Si 3 N 4) is formed on the recording surface of the substrate 43 as shown in the sectional view of FIG.
6a, a magneto-optical recording layer 47 made of TbFeCo, a dielectric layer 46b made of silicon nitride, and an aluminum alloy (A
1-Ti), a 2P film is formed on the reflective layer 44 so as to cover almost the entire surface of the substrate.
The resin was smooth coating, it is cured by light irradiation of the UV lamp, a protective film 45.

In this way, MD Data 2 as a recording medium according to the present embodiment can be completed. It is needless to say that the material for forming the dielectric layer and the magneto-optical recording layer of MD Data2 is not limited to the above, and various other materials can be applied.

EXAMPLE According to the method of manufacturing MD Data 2 described above, three (three types) magneto-optical disks for evaluation (Type-A, Type-B, Type) having different pit track pitches 301 and groove track pitches 302 were used.
-C).

In manufacturing these evaluation magneto-optical disks, first, three types of master disks 11 were manufactured. At this time, the exposure conditions of the grooves 202a and 202b were such that the groove track pitch 302 was 0.95 μm or 0.92 μm, the exposure power (laser power) was 1.0 mW, and the wobble amount of the groove 202b was ± 20 nm. On the other hand, the exposure conditions of the pit 201 were such that the pit track pitch 301 was 0.95 μm for Type-A, 0.98 μm for Type-B, 1.00 μm for Type-C, and the exposure power was 0.5 mW. Laser beam 2 at this time
The linear velocities of 1a and 21b with respect to the surface of the glass master were 2.00 m / s. The resist thickness was the same for all three types of masters 11 corresponding to the three types of evaluation magneto-optical disks.

In patterning the latent image of the pit 201, the clock frequency is 8.82 MHz and the shortest pulse is 2T = 227 ns.
Using the modulation signal, the correction amount Δ
Obtaining a control signal as shown in FIG. 4 (B) was shortened by C = 80 ns. Based on this control signal, the modulation optical system 7
2T = 147 ns, 4T = 374
By controlling the pulse output to be ns, 8T = 827 ns, a sufficiently large exposure pulse for the pit 201 can be formed.

A stamper was manufactured using each of the three types of masters 11, and three types of magneto-optical disks for evaluation were manufactured using the stampers. Then, these magneto-optical disks were mounted one by one on an evaluation device, and various characteristics were evaluated in each case. The evaluation device used at this time has a reading / writing laser wavelength of 660 n.
equipped with an optical pickup with m and NA of 0.52, MD
This is a general one set to evaluate a Data2 format magneto-optical disk.

First, when the pit width and groove width of each of the three types of manufactured magneto-optical disks for evaluation were measured by a scanning electron microscope, the pit width of each of the magneto-optical disks was about 0.43 μm on average. And the groove width was about 0.28 μm.

Subsequently, various characteristics as a magneto-optical disk were evaluated by an evaluation device. At this time, the items that have the strongest influence on the read / write performance are shown in FIG.
The servo signal amount (Push-Pull signal amount), the RC signal amount, and the items related to the MD Data2 standard as shown in FIG.
Pit modulation (I2 / Itop), S in radial direction of disc
The EW characteristic (Rad. Skew) and the pit reproduction characteristic (Jitter) other than those shown in FIG. 5 were evaluated.

In evaluating such items, the recording laser power was fixed to 8.0 mW as the MO signal, and a pulse train of recording laser pulses with a duty ratio of 50% was used. Recorded at linear velocity. Then, the recorded MO signal is changed to 2.0
Reproduction was performed with the reproduction laser power fixed at 1.0 mW at a linear velocity of m / s, and the jitter, skew, and the like at that time were measured. The jitter was measured by using a time interval analyzer TA320 manufactured by Yokogawa Electric Corporation and standardizing the value of σ to 227 ns. The skew characteristic in the radial direction is set to a range in which the value of the jitter is 15.0% or less by tilting the disk.

FIG. 6 shows the characteristics of the pit 201 evaluated in this manner. FIG. 7 shows various characteristics of the data recording portions formed in the grooves 202a and 202b and the lands 250a and 250b therebetween. FIG. 8 shows the combinations of the pit track pitch 301 and the groove track pitch 302 including the settings other than the magneto-optical disk manufactured for evaluation in the present embodiment and their ratios. From these evaluation results, things like the following has been confirmed.

First, from the results shown in FIG. 6, as the pit track pitch 301 increases from 0.95 μm to 0.98 μm and further to 1.00 μm, the servo signal amount, the RC signal amount, the pit modulation degree, and the Skew characteristic become larger. In any case, the jitter increases and the jitter decreases, and the characteristics become better. The result of any of these settings is M
This satisfies the standard of D Data2.

However, in particular, the pit track pitch 301
When but focusing on the case of 0.95 .mu.m, RC signal of this time (RC = 0.146) and Skew characteristics (Rad
Skew = 0.72) is the lower limit of the MD Data2 standard (RC ≦ 0.14, Rad Skew ≦ 0.70)
It has become about. Therefore, it is considered appropriate that the track pitch of the pit 201 is set to 0.95 μm as the practical lower limit.

Further, from the results shown in FIG. 7, the groove track pitch 302 is set to be 0.950 μm to 0.92 μm.
, The RC signal amount, pit modulation degree, Ske
Although the w characteristics are deteriorated, all of them satisfy the MD Data2 standard. In order to comply with the MD Data2 standard, the groove track pitch 30
2 is required to be a value within a range of 0.95 ± 0.03 μm. Therefore, the groove track pitch 302
It is preferable that the lower limit is 0.92 μm and the upper limit is 0.98 μm.

The maximum value of the pit track pitch 301 in the above evaluation experiment is 1.00 μm, and the minimum value of the groove track pitch 302 is 0.92 μm. By the groove track pitch 302 with such a setting the pit track pitch 301 to the maximum to the minimum, it is possible to maximize the various properties relating to the reading of the pit 201, and data within a range that satisfies the specifications of the MD Data2 it is possible to maximize the storage capacity of. The track pitch ratio for this combination is
1.00 / 0.92 = 1.087.

The practical lower limit of the pit track pitch 301 is set to 0.95 μm in consideration of a safety factor, and the minimum value of the groove track pitch 302 is set to 0.9.
In the case of 2 μm, both track pitches are practically and the minimum setting in the standard, and the recording capacity of one entire disc can be practically maximized. The track pitch ratio for this combination is 0.95 / 0.9
2 = 1.033.

If the recording capacity is not taken into consideration, the MD
The groove track pitch 302 is set to a value of 0.95 μm or more and 0.98 μm or less within a range conforming to the Data 2 standard, and the pit track pitch 301
Can be set to be more than 1.00 times to 1.087 times or less than the groove track pitch 302, for example, 0.98 μm. However, in practice, there is a strong demand for achieving a large recording capacity, and for that purpose, the groove track pitch 302 is set to 0.1.
It is desirable that the pitch be less than 95 μm, and that the pit track pitch 301 be 0.95 μm or more. Pit 201 and groove 2 for this combination
02a and 202b are 1.00 in track pitch.
It is super.

As described above, the groove track pitch 3
02 is set in the range of 0.92 μm to 0.98 μm, more preferably 0.92 μm to 0.95 μm, and the pit track pitch is set in the range of 0.95 μm to 1.00, and The pit track pitch 301 is changed to the groove track pitch 3
By making the pit 201 more than 1.00 times to 1.087 times or less, the grooves 202a, 202 can be satisfied while sufficiently satisfying the standards of various characteristics relating to the reading of the pit 201.
b to reduce the radial density of the disk
It has been demonstrated that a large-capacity MDdata-2 capable of recording and reproducing for a long time using a recording and reproducing apparatus for D can be realized.

In the above embodiment, the case where the present invention is applied to a large-capacity MD Data2 magneto-optical disk capable of recording and reproducing data has been described. However, the technology of the recording medium according to the present invention is as follows. In addition to the MD Data2 format, it is needless to say that the present invention can be applied to various other optical disks and the like as long as the pits and the grooves are not connected in one spiral.

[0063]

As described in the foregoing, according to the manufacturing method of the recording medium and the recording medium master and recording medium of the present invention, the track pitch of the pits is set wider than the track pitch of the grooves, the ratio 1. More than 00 to 1.
087 or less, optical detection of pits can be reliably performed, and MD Dat
An effect that can be achieved capacity of the data recording area while still conforming to the standards of the recording and reproducing characteristics defined in a2 standards.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an optical recording device used when manufacturing a recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing pits and grooves of a recording medium according to one embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a recording medium.

FIG. 4 is a timing chart showing a 1-7 modulation signal (A) and a control signal (B) used when patterning a latent image of a pit.

FIG. 5 is a diagram showing main specifications regarding recording / reading characteristics in the MD format.

FIG. 6 is a diagram collectively showing evaluation results on pit characteristics in three evaluation magneto-optical disks manufactured in the example.

FIG. 7 is a view collectively showing evaluation results on groove characteristics in three evaluation magneto-optical disks manufactured in Example.

FIG. 8 is a diagram collectively showing combinations of track pitches of pits and grooves of three types of evaluation magneto-optical disks evaluated in the examples, and a ratio of track pitch for each of those combinations.

FIG. 9 is a diagram showing a schematic configuration of a conventional general single spiral MD.

[Explanation of symbols]

201: pit, 202a, 202b: groove, 1 ...
Laser light source, 2 ... Electro-optical modulator, 3 ... Automatic light intensity controller, 4 ... Photodetector, 5 ... Analyzer, 6a, 6b ...
Beam splitters, 7a, 7b: modulation optical system, 8: λ /
2 polarizing plates, 9a, 9b reflection mirror, 10 moving optical table, 12 turntable, 13 spindle servo, 14 voltage frequency controller, 15 drive circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/125 G11B 7/125 Z 7/26 501 7/26 501 11/105 521 11/105 521F 521E 521H 521G 546 546D (72) Inventor Masayuki Takakuwa F-term (reference) in Sony Corporation 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo 5D029 JB09 WA02 WA09 WA17 WA20 WA26 WB11 WC01 WC10 WD10 WD11 WD22 5D075 EE03 FG18 5D090A01 CC14 FF11 GG02 GG03 GG09 5D119 AA11 AA22 BA01 FA02 JB02 5D121 BB01 BB26

Claims (12)

[Claims] 1. A pit and a groove are formed on the surface of a disk-shaped substrate so as to form separate continuous tracks, and information carried by the pits or the grooves is continuously transferred along each track. A recording medium set to be readable, wherein a ratio of a track pitch of the pit to a track pitch of the groove is set to be more than 1.00 to 1.087 or less. 2. The track pitch of the groove is 0.9.
2. The recording medium according to claim 1, wherein the thickness is set to 2 μm or more and less than 0.98 μm. 3. A pit and a groove are formed on the surface of a disk-shaped substrate so as to form separate continuous tracks, and information carried by the pits or the grooves is continuously transferred along each track. A recording medium master used for forming the pits and the grooves on the surface of the substrate in a step of manufacturing a recording medium set to be readable, wherein a track pitch of the pits relative to a track pitch of the grooves is provided. Characterized in that the ratio is set to be more than 1.00 to 1.087 or less. 4. The track pitch of the groove is 0.9.
4. The recording medium master according to claim 3, wherein the thickness is set to 2 μm or more and less than 0.98 μm. 5. A pit and a groove form separate continuous tracks on the surface of a disk-shaped substrate, and information carried by the pits or the grooves can be continuously read along each track. In manufacturing the set recording medium, the pit and the groove are formed by setting a ratio of a track pitch of the pit to a track pitch of the groove to be more than 1.00 to 1.087 or less. manufacturing method of the recording medium. 6. A pit and a groove form separate continuous tracks on the surface of a disk-shaped substrate, and a laser having a wavelength of 0.655 ± 0.01 μm is applied along the tracks to an NA of 0.52 ±. Irradiating with an optical system of 0.01, it is a recording medium set so that the information carried by the pit and the groove can be continuously read, wherein the ratio of the track pitch of the pit to the track pitch of the groove is A recording medium characterized by being set to more than 1.00 to 1.087 or less. 7. The recording medium according to claim 6, wherein said groove is configured by a double spiral of a straight groove and a wobbling groove. 8. The recording medium according to claim 6, wherein said pit is a single spiral, and said groove is a double spiral. 9. The recording medium according to claim 6, wherein the recording medium itself is a magneto-optical recording medium set so that information can be magneto-optically recorded. 10. A pit and a groove form separate continuous tracks on the surface of a disk-shaped substrate, and a laser having a wavelength of 0.655 ± 0.01 μm is applied along the tracks to an NA of 0.52 ± 0.01. and irradiating the optical system of 0.01,
A recording medium master used for forming the pits and the grooves on the surface of the substrate in a step of manufacturing a recording medium in which information carried by the pits and the grooves is set to be continuously readable. The ratio of the track pitch of the pit to the track pitch of the groove is set to be more than 1.00 to 1.087 or less. 11. The recording medium master according to claim 10, wherein said groove is constituted by a double spiral of a straight groove and a wobbling groove. 12. The recording medium master according to claim 10, wherein the pit is a single spiral and the groove is a double spiral.