JP4370756B2 - Optical recording / reproducing medium, master for producing optical recording / reproducing medium, method for producing optical recording / reproducing medium, and optical recording / reproducing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a plurality of concave and convex patterns such as pits and grooves set to be optically detectable, and other information patterns and grooves set to be capable of optical recording and reproduction are formed so as to form a spiral track. The present invention relates to an optical recording / reproducing medium, an optical recording / reproducing medium manufacturing master, an optical recording / reproducing medium manufacturing method, and an optical recording / reproducing apparatus.
[0002]
[Prior art]
In an optical recording / reproducing apparatus, an optical recording / reproducing medium is recorded by irradiating a signal recording layer on a substrate with light such as a laser beam while being mounted on a predetermined rotary table and rotated. The reflected light is detected and reproduction is performed. As an optical recording / reproducing medium, an optical disc such as a read-only CD-ROM (Compact Disc-Read Only Memory), a magneto-optical disc capable of rewriting a signal, or a phase change type optical disc is known.
[0003]
For example, in a recording medium such as MD (Mini Disc; registered trademark of Sony Corporation), in general, a groove for recording various information as a recording content, and a pit for recording information such as the type of the disc itself and a recording capacity. Is formed. The groove is formed in a groove shape along the circumferential direction of the disk. For example, when a wobble (wobble) groove is used, the planar pattern is meandering with a predetermined amplitude in the radial direction of the disk. Formed.
On the other hand, the pit is generally formed in a three-dimensional shape in which the planar pattern is a circle or an ellipse, and the width and length are reduced in the depth direction. A large number of pits are arranged along the circumferential direction of the disk to form one track.
[0004]
As an example, the groove is formed in the data recording area, the PIC (Permanent Information & Control Data) area is provided in the lead-in track area, and the pit (Table Of Contents) is used as information of the disk itself as described above. ) It is formed so as to carry information or information such as a pulse signal having a predetermined period. Therefore, in a conventional optical disk such as MD, a region where pits are formed and a region where grooves are formed are mixed, and these constitute a single spiral track as a whole.
[0005]
Generally, the width of the groove is set wider than the width of the pit. This is because the width of the groove for recording data is increased so that information can be recorded / reproduced more accurately. It is to make it. That is, when data is recorded in a narrow groove, noise increases and the S / N ratio decreases. Or, it is generally considered that data is recorded in a land portion wider than the groove. However, in the configuration where the wobble groove is used, the phases of adjacent grooves in the radial direction of the disk do not actually match. The width of the signal always changes and the fluctuation of the reproduction signal increases, which is not suitable for practical use. Therefore, it is desirable to record data in a wide groove.
[0006]
The conventional MD recording / reproduction time was set to 60 minutes or 74 minutes, but in recent years, a longer one of 80 minutes has also been proposed. In a general MD, a lead-in track area in which a pit carrying TOC information or the like is formed based on a unified standard or the like, the distance r from the center is r = 14.5 to 16.0 [mm]. The data recording area in which the groove for data to be recorded / reproduced is set as the area where the distance r from the center is r = 16.0 to 30.5 [mm].
[0007]
The recording / reproducing time is determined by the recording / reproducing speed (linear velocity) of the groove and the track pitch. In the MD standard, the linear velocity is 1.20 [m / s] or more and 1.40 [m / s] or less, The track pitch is 1.60 ± 0.10 [μm].
[0008]
When the recording / playback time setting is changed from 60 minutes to 74 minutes with respect to the recording / playback time, the linear velocity at the time of data reading, and the track pitch in such an MD having a spiral continuous track, Correspondingly, the linear velocity setting at the time of reading is changed from 1.40 [m / s] to 1.20 [m / s], and when the recording / reproducing time is changed from 74 minutes to 80 minutes, the linear velocity is already at the lower limit of the standard. Since the value is 1.20 [m / s], the track pitch setting is required to be changed from 1.60 [μm] to 1.51 [μm]. In order to lengthen (increase) the recording / reproducing time under the condition that the external dimensions of the disc and various characteristics of the optical pickup of the recording / reproducing apparatus are not changed, the linear velocity of reading is reduced or the track pitch is reduced. This is because it is necessary to make it shorter.
[0009]
By the way, in the conventional optical disk such as MD or magneto-optical (MO) disk, the pit track and the groove track are arranged in one spiral, and the pit and the groove have the same track pitch. Is set to Therefore, in the master disc manufacturing apparatus used in manufacturing the conventional optical disc, the pits and the track pitch are almost constant over almost the entire surface of the disc from the lead-in track area where the pits are formed to the data recording area where the grooves are formed. Groove pattern was engraved. Therefore, it is not considered to change the track pitch in the middle, but rather various techniques have been devised for maintaining a constant track pitch as accurately as possible.
[0010]
In particular, in the case of an MD capable of recording / reproducing for 80 minutes, the groove track pitch needs to be 1.50 to 1.51 [μm], which is narrower than the conventional 1.60 [μm]. Become. When the groove track pitch is set to 1.50 [μm], the conventional technique unifies the pit track pitch to 1.50 [μm].
[0011]
However, if both the pit track pitch and the groove track pitch are as narrow as 1.50 [μm], optical detection of the pits may be difficult or impossible. In other words, the MD standard has generally been standardized by determining the characteristics of servo signals such as push-pull signals and RC (Radial Constant) and pits at that time, based on a track pitch of 1.60 [μm]. Yes. Therefore, it is difficult for the track pitch of 1.51 μm to meet the general recording / reproduction characteristics standard defined in the MD standard in terms of push-pull signals, crosstalk, etc., particularly with respect to the pits. The inventors have confirmed by various experiments and analysis thereof.
[0012]
[Problems to be solved by the invention]
On the other hand, in the Japanese Patent Application No. 2000-248385, the present applicant sets the pit track pitch wider than the groove track pitch, and the ratio is set to be more than 1.00 to 1.13 or less. A method for manufacturing master and recording media was proposed. That is, in the prior art, since the groove track pitch and the pit track pitch are set to be the same, optical detection of the pits may be difficult or impossible. In the medium, the recording medium master, and the manufacturing method of the recording medium, the pit track pitch is made wider than the groove track pitch, and the ratio is set to more than 1.00 to 1.13 or less, so that the pit optical pitch is increased. Detection is possible and practical detection accuracy can be obtained.
[0013]
Note that by setting the groove track pitch to 1.50 [μm] or more and less than 1.70 [μm], the allowable range of the track pitch is set to 1.60 ± 0.10 [μm]. It is also possible to record and reproduce various types of information on the recording medium according to the present invention using a recording / reproducing apparatus.
[0014]
For example, in order to realize a recording medium capable of large capacity or long time recording / reproduction such as MD set to allow recording / reproduction for 80 minutes, the groove track pitch should be as narrow as about 1.51 μm. It is required to set and increase the data recording capacity. In this case, when the pit track pitch is set to 1.13 times which is the maximum value of the above ratio, the pit track pitch value is about 1.70 [μm], and the track pitch of both the groove and the pit is generally set. This is adapted to be within an allowable range of 1.60 ± 0.10 [μm], which is a track pitch condition in a typical recording / reproducing apparatus. Accordingly, the pit track pitch and the groove track pitch can be set to a pitch that can be recorded and / or reproduced by a general recording / reproducing apparatus.
[0015]
By the way, in a high-density optical disk such as DVR (Digital Video Recordable) which is currently being studied as an optical recording / reproducing medium having a higher recording density, that is, a large capacity, formats having different track pitches of pits and grooves have been proposed.
[0016]
For example, the BCA (Burst Cutting Area; the area where licensed data etc. are described by barcode) is a groove of 2000 nm, the track pitch of PIC is a rectangular wobble groove of 350 nm, and data recording A format has been proposed in which the track pitch of the region is 320 nm and a sine wave wobble groove or a triangular wave wobble groove is used.
[0017]
In such a configuration, in the boundary area between the BCA area on the inner circumference side, the PIC area, and the data recording area, there is no deterioration in recording / reproducing characteristics, so to speak, in the BCA area, the PIC area, and the data recording area. The problem is that a series of recording and reproduction is possible. However, under the present circumstances, the tracking servo signal at the change point from the PIC area (track pitch 350 nm) to the data recording area (track pitch 320 nm) is disturbed, and the tracking servo becomes unstable. Furthermore, it has been impossible to change the track pitch abruptly from the BCA region (track pitch 2000 nm) to the PIC region (track pitch 350 nm) and apply the tracking servo stably.
[0018]
The present invention solves such a problem, and even in an optical recording / reproducing medium that needs to set a plurality of track pitches, the optical recording / reproducing can stably perform tracking servo without causing deterioration of the recording / reproducing characteristics. It is an object to provide a medium, a method for manufacturing an optical recording / reproducing medium, and an optical recording / reproducing apparatus.
[0019]
[Means for Solving the Problems]
  An optical recording / reproducing medium according to the present invention comprises:,CircleA plurality of concavo-convex patterns are formed on the surface of the board-shaped substrate with two or more track pitches, and along the tracks of the concavo-convex patterns., Wavelength 405 ± 10nmLight for recording and / or playbackWith an objective lens with a numerical aperture NA = 0.85 ± 0.01An optical recording / reproducing medium on which recording and / or reproduction is performed by irradiation, a track is formed in one spiral, and a region between the concavo-convex patterns having a different track pitch among a plurality of concavo-convex patterns is as follows: The transition region in which the track pitch is gradually changed and the track pitch is a change amount of 5 times or more.Then, thatLength in the track directionxBut, The average distance of the transition region from the center of the optical recording / reproducing medium is r _m , Tp is the average track pitch of the plurality of concavo-convex patterns adjacent to the transition region _m And when
  100 mm ≦ x ≦ 2πr _m × 0.04 / Tp _m
StructureLet's make it.
[0020]
  The master for producing an optical recording / reproducing medium according to the present invention is,CircleA plurality of concavo-convex patterns are formed on the surface of the board-shaped substrate with two or more track pitches, and along the tracks of the concavo-convex patterns., Wavelength 405 ± 10nmLight for recording and / or playbackWith an objective lens with a numerical aperture NA = 0.85 ± 0.01A master for manufacturing an optical recording / reproducing medium that is irradiated and recorded and / or reproduced, wherein a track is formed in one spiral, and a plurality of concavo-convex patterns between the concavo-convex patterns having different track pitches. The region is a transition region in which the track pitch gradually changes, and the transition region has a change amount of 5 times or more in the track pitch.Then, thatLength in the track directionxBut, The average distance of the transition region from the center of the optical recording / reproducing medium is r _m , Tp is the average track pitch of the plurality of concavo-convex patterns adjacent to the transition region _m And when
  100 mm ≦ x ≦ 2πr _m × 0.04 / Tp _m
StructureLet's make it.
[0021]
  Furthermore, in the method for producing an optical recording / reproducing medium according to the present invention,,CircleA plurality of concavo-convex patterns are formed on the surface of the board-shaped substrate with two or more track pitches, and along the tracks of the concavo-convex patterns., Wavelength 405 ± 10nmLight for recording and / or playbackWith an objective lens with a numerical aperture NA = 0.85 ± 0.01An optical recording / reproducing medium manufacturing method in which recording and / or reproduction is performed by irradiation, wherein a track is formed in one spiral, and a region between concavo-convex patterns having a different track pitch among a plurality of concavo-convex patterns As the transition region where the track pitch gradually changes, the transition region where the track pitch is a change amount of 5 times or moreThen, thatLength in the track directionxThe, The average distance of the transition region from the center of the optical recording / reproducing medium is r _m , Tp is the average track pitch of the plurality of concavo-convex patterns adjacent to the transition region _m And when
  100 mm ≦ x ≦ 2πr _m × 0.04 / Tp _m
WhenTo form.
[0022]
  Furthermore, an optical recording / reproducing apparatus according to the present invention provides,CircleA plurality of concavo-convex patterns are formed on the surface of the board-shaped substrate with two or more track pitches, and along the tracks of the concavo-convex patterns., Wavelength 405 ± 10nmLight for recording and / or playbackWith an objective lens with a numerical aperture NA = 0.85 ± 0.01An optical recording / reproducing apparatus using an optical recording / reproducing medium which is irradiated and recorded and / or reproduced, wherein the track is formed in one spiral, and the above-mentioned plurality of concave / convex patterns of the optical recording / reproducing medium In the region between the uneven patterns with different track pitches, the track pitch is a transition region in which the track pitch gradually changes, and the transition region in which the track pitch is a change amount of 5 times or moreThen, thatLength in the track directionxBut, The average distance of the transition region from the center of the optical recording / reproducing medium is r _m , Tp is the average track pitch of the plurality of concavo-convex patterns adjacent to the transition region _m And when
  100 mm ≦ x ≦ 2πr _m × 0.04 / Tp _m
AndA series of recording / reproduction is performed on the track of the optical recording / reproducing medium.
[0023]
As described above, in the present invention, a plurality of concavo-convex patterns having two or more track pitches are provided. Particularly, the concavo-convex pattern having the minimum track pitch is provided with other concavo-convex patterns different from the track pitch. The ratio of the track pitch of the pattern is set to exceed 1.00 and equal to or less than 6.25, and a transition area where the track pitch gradually changes is provided in an area between the uneven patterns having different track pitches, thereby making the track 1 One spiral is formed and configured. By adopting such a configuration, for example, a series of recording / reproduction of the concavo-convex pattern corresponding to each BCA or PIC area and a concavo-convex pattern such as a groove in the data recording area, that is, continuous recording / reproduction is performed. It is possible to provide an optical recording / reproducing medium that can be used.
[0024]
That is, in the conventional configuration, when the track pitch of the groove and the track pitch of the BCA or PIC are greatly different, it is necessary not to access this area because the tracking servo is not applied in the area where the track pitch changes. Further, if the ratio of the track pitch is to be kept small, there is a case where recording on the BCA portion is impossible or optical detection of the rectangular wobble of the PIC is difficult or impossible. In this case, a series of recording / reproduction of each pattern is possible, and recording to the BCA section and optical detection of the rectangular wobble of the PIC can be reliably performed.
[0025]
For example, the track point is changed by gradually changing the track pitch from the BCA area (track pitch 2000 nm) to the PIC area (track pitch 350 nm) and from the PIC area (track pitch 350 nm) to the data recording area (track pitch 320 nm). Servo tracking servo can be realized without disturbance of servo signal. With such a configuration, it is possible to provide an optical recording / reproducing medium having good recording / reproducing characteristics and an optical recording / reproducing apparatus using the same.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following examples, the present invention is applied to an optical recording / reproducing medium having a DVR type structure, its master, a manufacturing method, and an optical recording / reproducing apparatus. However, the present invention is not limited to this, and various other types. Can be modified and changed.
[0027]
FIG. 1 is an explanatory diagram showing a schematic cross-sectional configuration of an optical recording / reproducing medium according to an embodiment of the present invention. As shown in FIG. 1, the optical recording / reproducing medium according to the present invention has a plurality of concave and convex patterns on a substrate 1, and first to third concave and convex patterns 11 to 13 in the illustrated example. On the substrate 1, for example, a reflective layer 2, a dielectric layer 3, a recording layer 4, a dielectric layer 5 and a protective layer 6 are sequentially laminated. In this example, the recording is performed from the protective layer 6 side. And, for example, light L such as a laser beam for reproduction, in this case, for example, is irradiated onto each pattern via the optical pickup 14, and the recorded content is reproduced, for example.
[0028]
In this example, the DVR type configuration is adopted as described above, and the planar configuration of each pattern is such that, as shown in FIG. A second pattern 12 having a narrower track pitch than the second pattern 12 is formed as a rectangular pit pattern in the above-described PIC region, and a third pattern 13 having a narrower track pitch is formed. In the recording area, for example, a wobble groove is formed as a sine wave.
[0029]
The BCA region has a distance from the center, that is, the radius r is between r = 21.3 [mm] to 22.2 [mm], and the PIC region is between the radius r = 22.24 [mm] to 23.2 [mm]. The data recording areas are respectively formed within a radius r = 23.2 [mm] to 58.5 [mm].
[0030]
In the present invention, the ratio of the track pitches of these patterns is selected to be more than 1.00 and not more than 6.25. In the example shown in FIG. 1, the track pitches of the first to third concavo-convex patterns 11 to 13 are set to Tp, respectively.₁, Tp₂And Tp_ThreeThen, Tp₁= 2000 nm, Tp₂= 350 nm, Tp_Three= 320 nm, and the ratio of the track pitch of the first and second concavo-convex patterns to the track pitch of the third concavo-convex pattern 13 having the smallest track pitch is 1.09 and 6.25, respectively.
[0031]
Thus, the ratio of the track pitch of each pattern is set to be a value exceeding 1.00 and not exceeding 6.25. When this optical recording / reproducing medium is a so-called DVR, the groove track pitch of the data recording area is 320 nm. This is to make it possible to obtain a large capacity capable of recording / reproducing for a longer time by narrowing the pitch.
[0032]
In the present invention, a transition region in which the track pitch gradually changes is provided at the boundary portion between the plurality of uneven patterns set for each track pitch. That is, in the first transition region 14 shown in FIG. 2, the tracking pitch is gradually changed from 2000 nm to 350 nm, and in the second transition region 15, the tracking pitch is gradually changed from 350 nm to 320 nm. Thus, it was possible to avoid the deterioration of the recording / reproducing characteristics.
[0033]
The process of forming each concavo-convex pattern by gradually changing the track pitch in this way will be described in detail with reference to FIG. 3 showing the configuration of an example of an optical recording apparatus.
An optical recording / reproducing medium or an optical recording / reproducing medium master according to an embodiment of the present invention is provided by a method of exposing a pit or groove pattern by this optical recording apparatus, a method of manufacturing an optical recording / reproducing medium including the same, or the like. Since they are embodied, they will be described together below.
[0034]
As shown in FIG. 3, the optical recording apparatus includes a light source 20 such as a laser, a mirror 21 and a mirror 22, a drive circuit 26, a voltage frequency controller 27, a position sensor 30, a laser scale 31, a slide servo 32, and an air slider 33. The moving optical table 40, the turntable 34 on which the master substrate 51 is placed, the spindle shaft 35, and the spindle servo 36 are included. An alternate long and short dash line c indicates the rotation axis of the spindle shaft 35.
[0035]
As the light source 20, for example, a recording laser having a wavelength λ = 266 nm for performing a predetermined pattern exposure on the photosensitive layer 52 on the master substrate 51 can be used. It is not limited only to the light source. The laser light B emitted from the laser light source 20 travels straight as a parallel beam, is reflected by the mirror 21 and the mirror 22, changes its direction, and is guided to the moving optical table 40.
[0036]
On the moving optical table 40, two wedge prisms 23 and 25 and one acoustooptic modulator / acoustic deflector (AOM / AOD) 24 sandwiched between the two prisms 23 and 25 are arranged. The acoustooptic modulation deflector 24 is arranged so that the laser beam incident as a parallel beam satisfies the Bragg condition with the grating surface of the acoustooptic element, and the beam B emitted from the wedge prism 25 is horizontal. The wedge prisms 23 and 25 are arranged so that the height does not change. As an acoustooptic element used for the acoustooptic modulation deflector 24, tellurium oxide (TeO) is used.₂) Is preferred.
[0037]
A predetermined signal is supplied from the drive circuit 26 to the acousto-optic modulation deflector 24. This signal is a DC signal of a certain level when a groove is formed. The drive circuit 26 is supplied with a high frequency signal from a voltage frequency controller (VCO) 27. A control signal is supplied to the voltage frequency controller 27. The control signal from the voltage frequency controller 27 is a zero-level direct current (DC) signal when forming a BCA DC groove, and a biphase rectangular signal when forming a PIC rectangular wobble groove. When forming a Sin wobble groove in the data recording area, the signal is 956.5 kHz. The 956.5 kHz signal records address wobble information.
[0038]
The acousto-optic modulation deflector 24 utilizes the fact that the intensity of the first-order diffracted light in Bragg diffraction is approximately proportional to the ultrasonic power, and modulates the ultrasonic power based on the recording signal to generate the light of the laser beam B. Modulate. As described above, in order to realize Bragg diffraction, the Bragg condition; 2 d sin θ = nλ (where d: lattice spacing, λ: laser light wavelength, θ: angle between laser light and lattice surface, n: integer) The positional relationship and attitude of the acoustooptic modulation deflector 24 with respect to the optical axis of the laser beam are set so as to satisfy the above.
[0039]
In this optical recording apparatus, a first concave / convex pattern 11 having a 2000 nm track pitch groove array in the BCA area, a second concave / convex pattern 12 having a 350 nm track pitch rectangular wobble groove array in the PIC area, and a data recording area. The linear velocity in the longitudinal direction of the track is 5.28 m / sec so that the third concave-convex pattern 13 which is a wobbling groove wobbled by a sine wave is formed in the photosensitive layer 52 in a spiral pattern. While controlling the rotation speed of the turntable 34 so as to be s, the feed pitch of the moving optical table 40 is 2000 nm in the BCA area, 350 nm in the PIC area, and 320 nm in the data recording area.
[0040]
The moving optical table 40 detects the position by the position sensor 30 and performs exposure at timings and pitches corresponding to the respective areas, so that the latent images of the above-described concavo-convex patterns of the BCA, PIC, and data recording areas are obtained. It is possible to expose the photosensitive layer 52 on the master 51 at a predetermined pitch. Further, the operation of the slide servo 32 and the air slider 33 is controlled based on the wavelength detected by the laser scale 31 (for example, 0.78 [μm]), and the feed pitch of the moving optical table 40 is instantaneously changed. However, as described above, in this example, a region in which the feed pitch is gradually changed and the track pitch is gradually changed is provided in the boundary region between the regions.
[0041]
That is, during the BCA area (radius r = 21.3 [mm] to 22.2 [mm]), the pattern exposure corresponding to the first concavo-convex pattern 11 is performed with a feed pitch of 2000 nm, and the track pitch changes first. In the transition region 14 (radius r = 22.2 [mm] to 22.24 [mm]), the feed pitch is gradually changed from 2000 nm to 350 nm. The feed pitch is 350 nm in the PIC region (radius r = 22.24 [mm] to 23.2 [mm]), and the feed pitch is in the second transition region 15 (radius r = 23.2 [mm]). Is gradually changed from 350 nm to 320 nm. A data recording area (radius r = 23.2 [mm] to 58.5 [mm]) is formed at a feed pitch of 320 nm.
[0042]
The laser beam B modulated and deflected as described above passes through the magnifying lens 28 and is irradiated to the photosensitive layer 52 of the master 51 by the mirror 29 and the objective lens 37, and the desired BCA and PIC and the latent area of the data recording area groove are irradiated. Form an image.
[0043]
Subsequently, the master 51 is subjected to development processing, and the exposed portion of the photosensitive layer 52, that is, the resist is dissolved to perform development. That is, although not shown, in a state where the master 51 is placed on the turntable of the developing machine, the developer is dropped on the surface of the master 51 by rotating with the turntable to develop the resist on the surface, and the BCA region ( A first concavo-convex pattern composed of a groove of 2000 nm track pitch), a second concavo-convex pattern composed of a rectangular wobble groove in a PIC area (350 nm track pitch), and a wobbling groove formed as a sine wave wobble in the data recording area. A master for producing an optical recording / reproducing medium can be obtained in which each concave / convex pattern is formed as a single spiral pattern.
[0044]
The magnifying lens 28 has a focal length of, for example, 50 [mm], and the numerical aperture NA of the objective lens 37 is, for example, 0.9, so that the track pitch of each of the concave and convex patterns can be satisfactorily maintained. It is.
[0045]
In this way, optical recording / reproduction that enables recording / reproduction of an optical recording / reproducing medium having a DVR type configuration by a DVR type recording / reproducing apparatus and that can accurately read a series of information in the BCA area, the PIC area, and the data recording area is possible. A master for producing an optical recording / reproducing medium for a medium can be obtained.
[0046]
Next, a process of creating a stamper capable of forming a large number of optical recording / reproducing medium substrates from the master for manufacturing the optical recording / reproducing medium will be described with reference to the process diagrams of FIGS. FIG. 4A shows an enlarged cross-sectional configuration of a main part of an optical recording / reproducing medium manufacturing master 60 created by the above-described optical recording apparatus and developing machine. 4A shows only the first and second uneven patterns 53A and 53B, it goes without saying that the third uneven pattern is also formed in the extended region.
[0047]
On the master 60 for manufacturing the optical recording / reproducing medium, a conductive film layer made of a nickel film is formed by an electroless plating method or the like, and the master 60 on which the conductive film layer is further formed is attached to an electroforming apparatus. As shown in FIG. 4B, a plating layer 54a made of nickel or the like is formed on the conductive film layer by an electrical plating method so as to have a thickness of about 300 ± 5 [μm]. Subsequently, as shown in FIG. 4C, the nickel plating layer 54a is peeled off from the master 60 with a cutter or the like, and the photosensitive layer 52 such as photoresist on the signal forming surface of the nickel plating layer 54a, that is, the concavo-convex pattern forming surface, is cleaned using acetone or the like. Then, the stamper 54 is produced. The stamper 54 has first and second concavo-convex patterns 55A and 55B in which the concavo-convex pattern is reversed from the patterns of the first and second concavo-convex patterns 53A and 53B formed on the photosensitive layer 52 by the exposure of the optical recording apparatus described above. It is formed.
[0048]
Further, from this stamper 54, a mother stamper 56 having an uneven surface is produced. That is, after applying a predetermined release layer or the like to the pattern surface of the stamper 54, applying a plating layer by an electroplating method or the like, and further peeling the plating layer with a cutter or the like, as shown in FIG. 4D. The mother stamper 56 in which the first and second concavo-convex patterns 57A and 57B in which the concavo-convex pattern is reversed from that of the first and second concavo-convex patterns 55A and 55B described above can be produced.
[0049]
Next, an optical recording / reproducing medium for evaluation was produced as follows. First, a substrate for an optical recording / reproducing medium is manufactured by injection molding from a mother stamper 56 using a transparent resin of polycarbonate (refractive index 1.59), and first to third pits, grooves, etc. formed on the surface thereof. The concavo-convex patterns 11 to 13 are transferred. The molded substrate thickness is about 1.1 mm.
[0050]
On this signal forming surface, as described in FIG. 1, the reflective layer 2 made of Ag alloy or the like, ZnS-SiO₂And the like, a recording layer 4 made of a phase change material such as GeSbTe alloy, and a ZnS-SiO₂A dielectric layer 5 made of, for example, is sequentially formed by sputtering. Thereafter, an ultraviolet curable resin or the like is applied onto the dielectric layer 5 by a spin coating method, and the ultraviolet curable resin is irradiated with ultraviolet rays and cured to form, for example, a protective layer 6 having a thickness of 0.1 mm. . Through the above steps, an optical recording / reproducing medium having a phase change recording layer having a DVR structure is manufactured.
[0051]
[Example]
DVR discs having different BCA, PIC, and data recording area track pitches were manufactured by the method for manufacturing an optical recording / reproducing medium having the DVR configuration described above. The operation of evaluating the concave / convex pattern of the optical recording / reproducing medium is evaluated using a DVR evaluator equipped with an optical pickup having a wavelength of 406 nm and a numerical aperture NA = 0.85.
[0052]
In this example, tracking was performed by a differential push-pull (DPP) method using three laser beams irradiated at predetermined intervals. FIG. 5 shows a main configuration of an optical system of an evaluation machine for a DVR type optical recording / reproducing medium.
[0053]
In FIG. 5, reference numeral 61 denotes a light source such as a semiconductor laser having a wavelength λ = 406 nm. A laser beam emitted from the light source is converted into parallel light by a collimator lens 62, and zero-order light (main beam) and ±± The beam is divided into three beams of primary light (sub beam). These three beams (P-polarized light) are transmitted through a polarizing beam splitter (PBS) 64 and a quarter-wave plate 65 as circularly polarized light, and are picked up by an optical pickup 66 including an objective lens having a numerical aperture NA = 0.85. The light is condensed on a predetermined recording track of the optical recording / reproducing medium 10. The center spot of the main beam is used for recording / reproducing recorded information, and the light spot of the sub beam is used for detecting a tracking error.
[0054]
In FIG. 5, reference numeral 68 denotes a rotating means for rotating the optical recording / reproducing medium 10 as indicated by an arrow d. An alternate long and short dash line e indicates the rotation axis of the optical recording / reproducing medium 10.
[0055]
Then, the reflected light from the optical recording / reproducing medium 10 passes through the optical pickup 66 and the quarter-wave plate 65 again, and the circularly polarized light becomes S-polarized light and is reflected by the polarization beam splitter 64 and enters the combination lens 71. .
[0056]
The laser light incident on the combination lens 71 is incident on the photodiode 72 through a lens that gives astigmatism to the laser beam, is converted into an electric signal corresponding to the intensity of the beam, and is a servo signal, that is, a focus error signal and tracking. An error signal is output to the servo circuit. The photodiode 72 has a divided detector 73 (A to H). The return light of the main beam is incident on the quadrant detectors A to D located at the center of the detector 73, and the return light of the sub beam is incident on E to H located on both sides of the detector 73.
[0057]
  As described above, in this example, the tracking servo signal is obtained by the differential push-pull method.
  That is, the signals A to H output from the detectors A to H of the detector 73 are added and subtracted as follows in a predetermined circuit system (not shown) to output the following signals. That is,
  Reproduction signal (MO signal) of optical recording / reproduction medium = (A + B + C + D)
  Pit reproduction signal (for example, EFM signal) = (A + B + C + D)
  Push-pull signal = (B + C)-(A + D)
  Differential push-pull (tracking servo) signal
                  = (B + C)-(A + D) -k{(EF) + (GH)}
                                (K is a predetermined constant)
And
[0058]
As a result of evaluating the recording / reproducing characteristics by the above-described evaluation machine, it is possible to realize a stable tracking with a sufficiently wide track pitch in the BCA region with a track pitch of 2000 nm, and a medium such as a manufacturing code or ID recorded in the form of a barcode in advance. I was able to reproduce the authentication code information. In the PIC region with a track pitch of 350 nm, the linear velocity, recording power, reproduction power, recording pulse (waveform) of an amplitude ± 100 nm rectangular wobble groove, and so-called the reflection layer 2 to the dielectric layer 5 described in FIG. Various information necessary for recording / reproducing of the medium, such as whether the recording unit has a single-layer structure or a two-layer structure, could be stably reproduced. Further, the above-described wobble signal of various information can be stably reproduced using the push-pull signal. In a data recording area with a track pitch of 320 nm, stable tracking servo and wobble groove address information could be stably reproduced. It was also possible to stably reproduce a wobble signal with an amplitude of ± 12 nm of ADIP (Address in pregroove) using a push-pull signal.
[0059]
In addition, recording / reproduction is performed with 1-7 modulation RF signals (A + B + C + D) in the wobble groove portion (recording area close to the reading surface) of the data recording area, and the jitter can be reproduced below 10% on the entire disk surface. The characteristics were realized.
[0060]
Further, since the track pitch is gradually changed from 2000 nm to 350 nm in the track pitch transition region (radius r = 22.2 [mm] to 22.24 [mm]) from the BCA region to the PIC region, Tracking was realized. Even in the track pitch transition region (radius r = 23.2 [mm]) from the PIC region to the data recording region, the track pitch was gradually changed from 350 nm to 320 nm, so that stable tracking could be realized. By the above-described method, a series of tracking could be stably realized in the entire region where the track pitch was 2000 nm to 350 nm and 350 nm to 320 nm.
[0061]
Even if the change amount of the track pitch was 2000 nm / 320 nm = 6.25 times as large as the change amount, a series of tracking could be stably realized in the entire region. The ratio of the track pitch of each concave / convex pattern in the BCA area, PIC area, and data recording area is set to be in the range of more than 1.00 to 6.25, and the change of the track pitch between the areas gradually changes. Just do it.
[0062]
In order to achieve high recording density, it is desirable to make the transition region as narrow as possible. For example, it is supposed that the tracking servo can usually follow up to several kHz. Therefore, when the linear velocity is determined, the upper limit of the transition region where the track pitch is changed can be roughly determined from the linear velocity and the servo band frequency.
However, it has been found that depending on the amount of change in the track pitch, the length of the transition region needs to be more than a certain level. This will be described below.
[0063]
For example, assuming that the linear velocity of the optical recording / reproducing medium is about 5 m / s and the tracking servo tracking band is 5 kHz, the length in the track direction obtained from this is:
5/5000 = 0.001 [m] = 1 [mm]
The above is considered sufficient.
[0064]
However, in the track pitch transition area 1 from the BCA area to the PIC area in the above-described embodiment, since the change amount of the track pitch is large, the length of the transition area in the track direction is about 100 mm or more. It was found that good tracking servo characteristics can be obtained.
[0065]
Further, in the track pitch transition area 2 from the PIC area to the data recording area in the above-described embodiment, since the change amount of the track pitch is small, the length of the transition area in the track direction is about 10 mm or more. It was also found that good tracking servo characteristics can be obtained.
[0066]
In the above embodiment, the width in the radial direction of the transition area where the track pitch changes from the BCA area to the PIC area is set to 0.04 mm. In order to increase the recording density, it is desirable to make the recording areas closer to each other. Therefore, it is desirable to make the transition area as short as possible.
Therefore, in the present invention, the average distance of the transition region from the center of the optical recording / reproducing medium is expressed as r._m, Tp is the average track pitch of each concavo-convex pattern adjacent to the transition region_mWhen the length x in the track direction of the transition region is
10 [mm] ≦ x ≦ 2πr_m× 0.04 / Tp_m
Is selected.
[0067]
  As described above, in the transition region where the track pitch changes from the BCA region to the PIC region, the track pitch changes from 2000 nm to 350 nm, that is, in this case, there is a change amount of 5 times or more. The length of the transition region in the track direction is 100mIt was found that stable tracking can be realized when the distance is greater than or equal to m. Therefore, when the amount of change is 2 times or less, such as an area where the PIC area transitions to the data recording area, when the length of the transition area in the track direction is 10 mm or more and the amount of change is about 5 times, It is desirable to be 100 mm or more.
[0068]
Therefore, it can be seen that by setting the length of the transition region in the track direction to 10 mm or more and 100 mm or less, high recording density can be achieved and good recording / reproducing characteristics can be maintained.
[0069]
In the above-described example, the case where the present invention is applied to a large-capacity optical disk such as a DVR has been described. However, the optical recording / reproducing medium, the master disk, or the manufacturing method thereof according to the present invention is not limited to a DVR or the like. Needless to say. In addition, the present invention can also be applied to various optical discs in which pits and grooves are connected in a single spiral shape, such as DVD-RW 4.7 GB. Also, the present invention can be applied to various optical discs having different track pitches in pits, grooves (DC, rectangular wobbles, sine wave wobbles) and other concavo-convex patterns and different track pitches between the regions.
[0070]
【The invention's effect】
As described above, according to the optical recording / reproducing medium, the optical recording / reproducing medium master, and the optical recording / reproducing medium manufacturing method of the present invention, pits and grooves (DC, rectangular wobble, sine wave wobble) are formed in one disc. The other uneven patterns can be set to different optimum track pitches, and sufficient recording / reproduction characteristics can be obtained in the respective formats.
[0071]
In addition, since the change of the track pitch between each area (format) is connected in one spiral shape, a series of tracking is stable in all areas in the optical recording / reproducing apparatus using this optical recording / reproducing medium. Can be realized.
[0072]
Furthermore, by appropriately selecting the length in the track direction of the transition region where the track pitch changes, an optical recording / reproducing medium that sufficiently satisfies the recording / reproducing characteristics and has a high recording density, and an optical recording / reproducing apparatus using the same are provided. can do.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic cross-sectional configuration of an example of an optical recording / reproducing medium.
FIG. 2 is an explanatory diagram showing a schematic plan configuration of an example of an optical recording / reproducing medium.
FIG. 3 is an explanatory diagram illustrating a configuration of an example of an optical recording apparatus.
FIG. 4 is a process diagram showing an example of a method for producing an optical recording / reproducing medium.
FIG. 5 is an explanatory diagram showing a configuration of a main part of an example of an optical recording / reproducing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate, 2 Reflection layer, 3 Dielectric layer, 4 Recording layer, 5 Dielectric layer, 6 Protective layer, 11 1st uneven | corrugated pattern, 12 2nd uneven | corrugated pattern, 13 3rd uneven | corrugated pattern, 14 1st Transition region, 15 Second transition region, 16 Optical pickup, 20 Light source, 21 Mirror, 22 Mirror, 23 Wedge prism, 24 Acousto-optic modulation deflector, 25 Wedge prism, 26 Drive circuit, 27 Voltage frequency controller, 28 Enlarge Lens, 29 Mirror, 30 Position sensor, 31 Laser scale, 32 Slide servo, 33 Air slider, 34 Turntable, 35 Spindle shaft, 36 Spindle servo, 40 Moving table, 51 Master substrate, 52 Photosensitive layer, 53A First Asperity pattern, 53B 2nd asperity pattern, 54a plating layer, 54 stamper 55A, first uneven pattern, 55B, second uneven pattern, 56 mother stamper, 57A, first uneven pattern, 57B, second uneven pattern, 60 master for producing optical recording / reproducing medium, 61 light source, 62 collimating lens, 63 Grating, 64 polarizing beam splitter, 65 1/4 wavelength plate, 66 optical pickup, 68 rotating means, 71 combination lens, 72 photodiode, 73 detector

Claims (4)

A plurality of concavo-convex patterns are formed on the disk-shaped substrate surface with a track pitch of 2 or more, and recording and / or reproducing light having a wavelength of 405 ± 10 nm is applied along the tracks of the concavo-convex patterns with a numerical aperture NA. = 0.85 ± 0.01 An optical recording / reproducing medium on which recording and / or reproduction is performed by irradiation with an objective lens ,
The track is formed in one spiral,
The region between the concavo-convex patterns with different track pitches among the concavo-convex patterns is a transition region where the track pitch gradually changes ,
In the transition region in which the ratio of the track pitch is a change amount of 5 times or more, the length x in the track direction has an average distance r _m from the center of the optical recording / reproducing medium in the transition region. the average of the track pitch between adjacent the plurality of uneven patterns when the Tp _{m,
100mm ≦ x ≦ 2πr m × 0.04} / Tp m
It is assumed
Light science recording and reproducing medium. A plurality of concavo-convex patterns are formed on the disk-shaped substrate surface with a track pitch of 2 or more, and recording and / or reproducing light having a wavelength of 405 ± 10 nm is applied along the tracks of the concavo-convex patterns with a numerical aperture NA. = 0.85 ± 0.01 An optical recording / reproducing medium manufacturing master that is irradiated and recorded and / or reproduced by an objective lens ,
The track is formed in one spiral,
The region between the concavo-convex patterns with different track pitches among the concavo-convex patterns is a transition region where the track pitch gradually changes,
In the transition region where the track pitch is a change amount of 5 times or more, the length x in the track direction is adjacent to the transition region, with the average distance of the transition region from the center of the optical recording / reproducing medium being r _m . the track pitch of the average of the plurality of uneven patterns when the Tp _{m,
100mm ≦ x ≦ 2πr m × 0.04} / Tp m
It is assumed
Light Science reproducing medium manufacturing master. A plurality of concavo-convex patterns are formed on the disk-shaped substrate surface with a track pitch of 2 or more, and recording and / or reproducing light having a wavelength of 405 ± 10 nm is applied along the tracks of the concavo-convex patterns with a numerical aperture NA. A method for producing an optical recording / reproducing medium in which recording and / or reproduction is performed by irradiation with an objective lens of 0.85 ± 0.01 ,
The track is formed into one spiral,
Of the plurality of concavo-convex patterns, a region between the concavo-convex patterns having different track pitches is a transition region in which the track pitch gradually changes.
In the transition region where the track pitch is a change amount of 5 times or more, the length x in the track direction is adjacent to the transition region, with the average distance of the transition region from the center of the optical recording / reproducing medium being r _m . the track pitch of the average of the plurality of uneven patterns when the Tp _{m,
100mm ≦ x ≦ 2πr m × 0.04} / Tp m
It is assumed
The method of manufacturing an optical science recording medium. A plurality of concavo-convex patterns are formed on the surface of the disk-shaped substrate with a track pitch of 2 or more, and recording and / or reproduction light with a wavelength of 405 ± 10 nm is generated along the tracks of the concavo-convex patterns with a numerical aperture NA = An optical recording / reproducing apparatus using an optical recording / reproducing medium that is irradiated with a 0.85 ± 0.01 objective lens for recording and / or reproduction,
The track is formed in one spiral,
Of the plurality of concavo-convex patterns of the optical recording / reproducing medium, a region between the concavo-convex patterns having different track pitches is a transition region in which the track pitch gradually changes,
In the transition region where the track pitch is a change amount of 5 times or more, the length x in the track direction is adjacent to the transition region, with the average distance of the transition region from the center of the optical recording / reproducing medium being r _m . the track pitch of the average of the plurality of uneven patterns when the Tp _{m,
100mm ≦ x ≦ 2πr m × 0.04} / Tp m
It is assumed
Light science recording and reproducing apparatus.

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