JP2003208719A - Optical recording/reproducing medium, stamper for producing optical recording/reproducing medium and optical recording /reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording/reproducing medium with a practically high recording density capable of sufficiently obtaining a push-pull signal amplitude even in pits for executing stable tracking servo without causing fluctuation in recording and reproducing characteristics. <P>SOLUTION: The optical recording and reproducing medium where pits corresponding to recording information are formed along recording tracks is configured such that a format inverting the ruggedness of a pit position detecting format is adopted for a recording format of the pits 3, and the track pitch of the pits is selected to be 4/3 or over and 3/2 or below of the track pitch of a cut-off frequency corresponding to a wavelength λ of reproduction light and a numerical aperture NA of an objective lens used for reproducing recording information of the optical recording and reproducing medium. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing medium in which pits corresponding to recorded information are formed along recording tracks, a stamper for manufacturing the optical recording / reproducing medium, and an optical recording / reproducing apparatus.

[0002]

2. Description of the Related Art As an optical recording / reproducing medium, various optical discs formed in a disk shape and optically recorded and / or reproduced have been put into practical use. Such optical discs include read-only optical discs in which embossed pits corresponding to data are formed in advance on the disc substrate, magneto-optical discs for recording data by utilizing the magneto-optical effect, and phase change of recording films. There is a phase-change type optical disk that records data by utilizing it.

Among these optical discs, writable optical discs such as magneto-optical discs and phase change type optical discs usually have grooves along the recording tracks formed on the disc substrate. Here, the groove is a so-called guide groove formed along the recording track mainly for enabling tracking servo, and a gap between the groove and an opening end of the groove is called a land.

In an optical disk having a groove formed therein, tracking servo is usually performed by a tracking error signal based on a push-pull signal obtained from light reflected and diffracted by the groove. Here, the push-pull signal is obtained by detecting the light diffracted and diffracted by the groove with two photodetectors symmetrically arranged with respect to the track center, and taking the difference between the outputs from these two photodetectors. Is obtained by

By the way, conventionally, in these optical discs, a high recording density has been achieved by improving the reproduction resolution of an optical pickup mounted in a reproducing apparatus. The improvement of the reproduction resolution of the optical pickup is mainly to shorten the wavelength λ of the laser light used for reproducing the data,
This has been achieved optically by increasing the numerical aperture NA of the objective lens that focuses the laser light on the optical disk.

Conventionally, a write-once type CD-R of a CD (Compact Disc) and a rewritable MD (Mi of a magneto-optical disc) are used.
ni Disc), a write-once type DVD-R or DVD + R of a DVD (Digital Versatile Disc), or a rewritable type of DVD, so-called DVD + RW or DVD-RW (both are registered trademarks of an optical disc). A groove recording format has been proposed. For each format of the ISO type magneto-optical disk, a land recording format for recording on a land has been proposed.

On the other hand, DVD-RAM (Random Access Memo)
In ry) etc., as one method for realizing high density of an optical disc, so-called land / groove recording in which the track density is doubled to increase the density by recording on both the groove and the land. A scheme has been proposed.

Further, DVR (Digital Video Recorable) which has been developed as a next-generation optical disk in recent years
Also, for a high density optical disc such as a μ-Disc in which the MD is downsized, a land / groove recording method has been studied, and thereby a high recording density is achieved.

However, when performing land-groove recording on a DVD-RAM or the like, in recording on the land and recording on the groove, the optimum recording / reproducing characteristics cannot be obtained unless the focus points are adjusted during recording / reproduction. There is a drawback in that the optical system is complicated.

In addition, "ISOM 2000 Simulation Of Heat Ge
In "neration And Conduction On Land / Groove Disc", it is clear that the recording beam shape is different between recording on the land and recording on the groove. It is difficult to make them uniform, and there is a problem that there are regions with different recording / reproducing characteristics in the same optical recording / reproducing medium.

Furthermore, in a high-density optical disc such as a DVR, the recording / reproducing characteristics on the land closer to the reading surface, that is, on the land closer to the light irradiation side are good in the case of the DVR,
It has been difficult to maintain good recording / reproducing characteristics in the groove farther from the reading surface, that is, in the case of DVR, farther from the light irradiation side.

Although it is possible at present to directly record a signal on a DVR-ROM (Read Only Memory) disk or the like in such a land-groove recording format, recording on a land and recording on a groove are possible. It is desired to make recording and reproducing characteristics good and uniform.

[0013]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In a high density optical disk such as R, the groove portion is far from the reading surface, and it is difficult to improve the recording / reproducing characteristics in this groove portion.

On the other hand, in the manufacturing process of the optical recording / reproducing medium, a method of manufacturing by inverting the concavo-convex pattern formed on the substrate can be considered. That is, in the usual manufacturing process of an optical recording / reproducing medium, a fine stamping pattern is formed on a photosensitive layer on a glass master by photolithography or the like, and then a master stamper made of, for example, Ni is formed by plating or the like.

Then, this master stamper is placed on a mold or the like and an injection molding method of injecting a resin, or on a substrate,
For example, a predetermined fine concave-convex pattern is formed on the surface by a so-called 2P (Photo-Polymerization) method in which an ultraviolet curable resin is applied and the stamper is pressed against the resin layer to form a desired concave-convex pattern. The substrate of the optical recording / reproducing medium can be formed.

Therefore, as described above, when the groove portion is provided on the side far from the reading light and the recording / reproducing characteristics cannot be maintained well, the duplicate stamper of the master stamper, that is, the so-called mother stamper is electroplated. By performing transfer formation by means such as the above, the concavo-convex pattern is reversed and the groove pattern on the substrate is provided on the side closer to the reading light, so that the recording / reproducing characteristics can be improved.

However, in the case of adopting the groove recording or land recording format, if an attempt is made to achieve the same high recording density as in the case of adopting the land groove recording format, the track density becomes twice as high as that in the case of adopting the land groove recording format. That is, the track pitch needs to be halved, and the amplitude amount of the tracking servo signal such as the push-pull signal becomes small, which makes it difficult to perform stable tracking and reproduce the wobble signal.

For example, in the land-groove recording format, the track pitch is 0.60 μm, that is, the land width is 0.30 μm and the groove width is 0.30 μm, and the push-pull signal amplitude is about 90%.

However, in order to achieve the same recording density in the groove recording format, the track pitch is set to 0.3.
If it is 2 μm, the push-pull signal amplitude is about 18%.

In the conventional optical disc, the track pitch is set to about twice to 3/2 of the track pitch of the cutoff frequency of the optical pickup of the reproducing apparatus. Here, the cut-off frequency is a frequency at which the reproduction signal amplitude becomes almost 0. The wavelength of the laser beam used for reproducing the data is λ, and the aperture of the objective lens for converging the laser beam on the optical disc. When the number is NA, it is represented by 2NA / λ.

In the case of the above DVR, numerical aperture NA = 0.8
5. Since the reproduction light wavelength λ = 406 nm, the cutoff frequency (2NA / λ) is 4187 lines / mm,
The track pitch in this case is 0.239 μm.

Assuming that the track pitch of the DVR is 0.32 μm, 4/3 (0.32 / 0.239 =) of the track pitch (0.239 μm) corresponding to the cutoff frequency.
It becomes about 1.339).

Normally, the track pitch is set to be about twice to 3/2 of the track pitch corresponding to the cutoff frequency, in order to realize stable tracking servo and stable wobble signal reproduction. Is required to be obtained at a sufficient level.

A push-pull signal is used as a tracking error signal in recent high-density optical disks, but the push-pull signal amplitude ratio must be about 0.15 or more in order to perform stable tracking servo. Furthermore, it is desired to stably reproduce the wobble signal.

On the other hand, in addition to recording on the groove, a format for recording information such as TOC (Table Of Contents) as pits has been proposed. However, the density of the pits in the circumferential direction is about half that of the pits, so that the tracking servo signal amplitude (push-pull signal amplitude) is halved.

That is, if the DVR track pitch is set to 0.32 μm for high density, the pit push-pull signal amplitude becomes about 9% (18% / 2), which makes tracking servo difficult. .

Incidentally, Japanese Patent Application Laid-Open No. 9-30 filed by the present applicant
In the 6034 publication, in an optical recording medium in which pits are formed on a recording track, when the refractive index of the substrate is n and the wavelength of light used for reproduction is λ, the pit depth is λ / ( 4n) to λ / (2n), the pit width is 0.3 μm to 0.6 μm, and the pit-formed area on the recording track on which the pit is formed is better than the non-pit-formed area. I also propose a configuration to increase.

However, in this case, in order to apply to a high recording density optical recording / reproducing medium having a track pitch of about 4/3 of the track pitch corresponding to the cutoff frequency as in the above-mentioned DVR, etc. It is necessary to consider the density in the direction along the recording track direction, the depth and width of the pits, and it has been desired to realize a high-density optical recording / reproducing medium capable of reliably maintaining good recording / reproducing characteristics. .

The present invention solves the above problems,
A practical high recording density optical recording / reproducing medium and a stamper for manufacturing an optical recording / reproducing medium, which can obtain a sufficient push-pull signal amplitude even in the pit portion for stable tracking servo without causing fluctuations in recording / reproducing characteristics. ,
Another object is to provide an optical recording / reproducing device.

[0030]

According to the present invention, in an optical recording / reproducing medium in which pits corresponding to recording information are formed along recording tracks, the recording format of the pits is reversed from the unevenness of the pit position detection format. The pit track pitch is the wavelength λ of the reproducing light for reproducing the recorded information on the optical recording / reproducing medium.
And the track pitch of the cutoff frequency corresponding to the numerical aperture NA of the objective lens is set to 4/3 or more and 3/2 or less.

Furthermore, the present invention provides a stamper for manufacturing an optical recording / reproducing medium for manufacturing an optical recording / reproducing medium in which pits corresponding to recording information are formed along recording tracks, in which a pit pattern corresponding to the pits is formed. The recording format is formed by reversing the irregularities of the pit position detection format, and the track pitch of the pit pattern is set to the wavelength λ of the reproducing light for reproducing the record information of the optical recording / reproducing medium and the numerical aperture NA of the objective lens. 4/3 or more of track pitch of corresponding cutoff frequency 3 /
Configured as 2 or less.

Furthermore, the present invention constitutes an optical recording / reproducing apparatus using the optical recording / reproducing medium having the above-mentioned structure.
That is, in an optical recording / reproducing apparatus using an optical recording / reproducing medium in which pits corresponding to recording information are formed along recording tracks, the recording format of the pits of the optical recording / reproducing medium is reversed to the unevenness of the pit position detection format. The track pitch of the pits of the optical recording / reproducing medium is the track pitch of the cutoff frequency corresponding to the wavelength λ of the reproducing light for reproducing the recorded information of the optical recording / reproducing medium and the numerical aperture NA of the objective lens. Of 4
It is configured as / 3 or more and 3/2 or less.

As described above, in the present invention, the pit recording format is configured as a space position detection format in which the irregularities of the pit position detection format are reversed, and the pit track pitch is recorded on the optical recording / reproducing medium. Extending the recording track by adopting a high-density structure in which the track pitch is 4/3 or more and 3/2 or less based on the cut-off frequency corresponding to the wavelength λ of the reproducing light for reproducing information and the numerical aperture of the objective lens. The pit density, that is, the pit duty, in the circumferential direction of the disk-shaped medium is 50%.
Will be increased. As a result, in the high density optical recording / reproducing medium, it is possible to surely obtain good tracking servo characteristics by increasing the push-pull signal amplitude.

The pit position detection method has a lower density in the circumferential direction of the pits, that is, a direction along the extension direction of the recording track, that is, a so-called pit duty, than the edge detection method which is generally used at present.

For example, in the case of the 2-7 modulation method (3T-8T), the pit duty of 3T is 33.3%.
The pit duty of T is 12.5%. In the case of 2-7 modulation pit position detection, the average pit duty becomes 22.7%, the push-pull signal amplitude decreases, and stable tracking servo becomes difficult.

On the other hand, in the present invention, the pit position detection format is formed as a space position detection format with the irregularities reversed. In this space position detection format, the unevenness of the pit position detection method is reversed, so that the pit duty is 77.3%, the push-pull signal amplitude does not decrease so much, and stable tracking servo becomes possible.

Further, assuming that the pit length of the pit position detection format is, for example, about 0.5T mark length, and adopting the space position detection format in which the unevenness is converted, the pit duty can be further improved. It is possible to set it to about 89.4%.

Therefore, when the structure of the present invention is applied to a high recording density optical recording / reproducing medium having a narrow track pitch, a sufficient push-pull signal amplitude can be stably obtained,
It is possible to avoid deterioration of recording / reproducing characteristics.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following examples, and various modifications are possible within the scope of the present invention. It goes without saying that the configuration can be adopted.

As described above, in the present invention, the pits corresponding to the recording information are formed along the recording track, and the format thereof is the space position detecting system in which the irregularities of the pit position detecting system are reversed.

In FIG. 1A, S is an example of a space position modulation signal according to the space position detection method, and 3 is a schematic view of the shape of a pit corresponding to this signal S. In addition, FIG. 1B schematically shows a modulation signal S ₁ according to the pit edge position detection method corresponding to the space position modulation signal and the shape of the pit 3 corresponding to the signal S ₁ . In FIG. 1B, the signal S ₁ is partially shown by arrows 3T _M , 3T _S , 8T _M ,
The areas indicated by 8T _s and 4T _M indicate 3T mark, 3T space, 8T mark, 8T space, and 4T mark, respectively.

Further, in FIG. 1C, the modulation signal S ₂ by the pit position detection method corresponding to the space position modulation signal and the edge position modulation signal is
The case where the pit length is approximately the same as the 1T mark and the shape of the pit 3 corresponding to the signal S ₂ are schematically shown.

Further, in FIG. 1D, the modulation signal S _{2 according} to the pit position detection method has a pit length of 1T.
A modulation signal S ₃ and a pit 3 corresponding to the modulation signal S ₃ when the length of the mark is half, that is, a length corresponding to 0.5T is shown. In FIG. 1E, the space position modulation in which the unevenness of the modulation signal S ₃ is inverted is shown. The signal S ₄ and the corresponding pit 3 are shown. In FIG. 1E, the space of each pit 3 of the space position modulation signal S ₄ has a length corresponding to 0.5T.

As can be seen by comparing these, FIG.
When the space position detection method shown in Fig. 1 is adopted, the pit duty is significantly improved as compared with the pit edge detection method and the pit position detection method, and in the space position detection method shown in Fig. 1E in which the space is further shortened, the pit duty is It can be seen that it is further improved.

FIG. 2 shows a schematic plan structure in which the pits 3 are recorded by the above-mentioned space position detection method, and the optical recording / reproducing medium is provided with the grooves 4, in this case, wobbled grooves.

In the configuration of the present invention, the wavelength of the reproducing light for reproducing the recorded information on the optical recording / reproducing medium is λ, and the refractive index of the medium from the incident side of the reproducing light of this optical recording / reproducing medium to the pit is n. Then, the phase depth x of the pit is set to λ / 13.71n ≦ x ≦ λ / 5.18n (1), and the ratio of the width w of the pit to the track pitch p of this pit is set to 0. 406 ≦ w / p ≦ 0.531 (2)

That is, for example, as shown in a schematic sectional view of one example in FIG. 3, on the substrate 1, on the side close to the light incident surface,
That is, in the illustrated example, the pits 3 and the grooves 4 are formed so as to project upward, and for example, the reflective layer 5, the first dielectric layer 6, the recording layer 7, and the second dielectric layer are formed thereon. 8 and the light-transmissive protective layer 9 are sequentially laminated to form the optical recording / reproducing medium 10.

Reference numeral 54 denotes an optical pickup such as an objective lens, and the pit 3 is irradiated with incident light L for reproduction such as laser light. In this case, the protective layer 9 serves as a medium that extends from the light incident surface to the pit, the refractive index thereof is n, and the wavelength of the reproducing incident light L is λ, and the above equations (1) and (2) are used.
And are used. In FIG. 3, w indicates the width of the pit and p indicates the track pitch of the pit.

The modulation method of the space position detection method described in FIG. 1 is an example of 2-7 modulation.
The present invention can also be applied to the case of other 1-7 modulation system or EFM modulation system.

Next, an example of the manufacturing process of such an optical recording / reproducing medium will be described with reference to the manufacturing process drawings of FIGS.

In FIG. 4A, reference numeral 11 denotes a master substrate made of glass or the like. A photosensitive layer 12 made of a photoresist or the like is adhered and formed on the surface of the master substrate 11, and a pit pattern 13 and a groove pattern having a pattern corresponding to recorded information are formed by performing predetermined pattern exposure and development by an optical recording device described later. 14 is formed, for example, so as to expose the surface of the master substrate 11, that is, as a so-called concave pattern in which the photosensitive layer 12 is removed.

Thereafter, although not shown, a conductive film made of a nickel film or the like is deposited on the entire surface of the patterned photosensitive layer 12 by electroless plating or the like, and then the conductive film is coated. The master substrate 11 thus attached is attached to an electroforming device and, for example, 3 is formed on the conductive film layer by electroplating.
A nickel plating layer is formed to have a thickness of about 00 ± 5 μm.

Subsequently, the nickel plating layer is peeled off from the master substrate 11 on which the nickel plating layer is thickly deposited by a cutter or the like, and the photosensitive layer on which the concavo-convex pattern is formed is washed with acetone or the like. As shown in FIG. 4B, a stamper 15 on which a reversal pit pattern 13n in which the pit pattern 13 on the master 11 is reversed and a reversal groove pattern 14n in which the groove pattern 14 is reversed, that is, a so-called master stamper is formed. It

After that, for example, a release agent is applied to the surface of the stamper 15 on which the concavo-convex pattern is formed, and then the stamper 1 is formed by, for example, an electroplating method, as shown in FIG. 4C.
A mother stamper 16 to which the uneven pattern 5 is transferred is formed.

The mother stamper 16 has a predetermined pit pattern 13 and a groove pattern 14 formed in a concave shape similar to the pattern of the photosensitive layer 12 on the master substrate 11 described in FIG. 4A. Therefore, the groove formed on the substrate by injection molding or the like from the mother stamper 16 has a pattern protruding from the substrate, and the groove surface can be on the side close to the incident side of the reproduction light.

The depth, width and track pitch of the pit pattern of the stamper 15 or the mother stamper 16 are also selected similarly to the above optical recording / reproducing medium.

That is, the refractive index of the medium from the light incident surface of the optical recording / reproducing medium to the pit is n, the wavelength of the incident light for reproducing the recorded information of the pit is λ, and the phase depth of the pit pattern 13 is x. , Λ / 13.71n ≦ x ′ ≦ λ / 5.18n.

As shown in an example in FIG. 4C, when the width of the pit pattern 13 is w'and the track pitch is p ', 0.406≤w' / p'≤0.531.

Next, the specific exposure process for the photosensitive layer 12 on the master 11 described in FIG. 4A will be described.
It will be described in detail together with a configuration example of the optical recording device.

First, the structure of this optical recording apparatus will be described. In the above-mentioned pattern exposure step, a method of converging a laser beam with an objective lens and exposing a photoresist on a master substrate is generally adopted. An example of such an optical recording device is shown in FIG.

In FIG. 5, reference numeral 20 denotes a light source such as a gas laser. The light source is not particularly limited,
Although it can be appropriately selected and used, in this example, a laser source that oscillates a recording laser beam of a Kr laser (wavelength λ = 351 nm) was used.

The laser light emitted from the light source 20 passes through an electro-optic modulator (EOM) 21 and an analyzer 22,
Beam splitter BS2 and beam splitter BS
It is partially reflected by 1. Beam splitter BS2
The laser light that has passed through BS1 and BS1 is detected by a photo detector (PD) 24, and is fed back to the modulator 21 in comparison with a comparison voltage in a control unit such as a recording light power control circuit (not shown).

The laser beams LB ₁ and LB ₂ reflected by the beam splitters BS1 and BS2 are modulated optical system OM1.
And OM2. In the modulation optical system OM1, the laser light is condensed by the lens L11 and the AOM is formed on the focal plane thereof.
1 (Acousto-Optic Modulator) is arranged.

An ultrasonic wave corresponding to the recording signal is input to the AOM 1 from the driver 25, and the intensity of the laser light is intensity-modulated based on the ultrasonic wave. Laser light is AO
Only the first-order diffracted light of the diffracted light which is diffracted by the diffraction grating of M1 is transmitted through the slit.

The first-order diffracted light subjected to the intensity modulation is reflected by the lens L.
After being condensed by 12, the light is reflected by the mirror M1 and the traveling direction is bent by 90 °, and then the λ / 2 wave plate HW
It is introduced horizontally to the movable optical table 40 via P and along the optical axis, and enters the polarization beam splitter PBS.

Similarly, in the modulation optical system OM2, the laser light is condensed by the lens L21, is incident on the AOM2 arranged on the focal plane thereof, and is based on the ultrasonic wave corresponding to the recording signal input from the driver 26. The intensity of the laser light is modulated. The diverged laser light is similarly condensed by the lens L22, reflected by the mirror M2, bent in the traveling direction by 90 °, and introduced horizontally to the movable optical table 40 along the optical axis.

When a groove is formed by the laser beam LB ₂ and this groove is used as a wobbled groove, it is optically deflected by the deflection optical system OD on the moving optical table 40 and then reflected by the mirror M4. The traveling direction is bent again by 90 ° and enters the polarization beam splitter PBS.

Then, the laser beam LB ₁ transmitted through the polarization beam splitter PBS and the polarization beam splitter PBS
Laser beam LB whose traveling direction is bent again by 90 °
₂ is made to have a predetermined beam diameter by the magnifying lens L3, is reflected by the mirror M5, and is guided to the objective lens 52. By this objective lens 52, the master substrate 11
Is focused on the photosensitive layer 12 above. Although not shown, the master substrate 11 is rotated by a rotation driving means as indicated by an arrow a. The alternate long and short dash line c indicates the central axis of the substrate 11.

The recording laser beams LB ₁ and LB ₂ are translated by the moving optical table 40. As a result, a latent image corresponding to the concavo-convex pattern corresponding to the irradiation trajectory of the laser light is formed on the entire surface of the photosensitive layer 12.

Here, the deflection optical system OD includes a wedge prism 47 and an acousto-optical deflector (AOD).
Deflector) 48 and wedge prism 49. The laser light LB ₂ enters the acousto-optic deflector 48 via the wedge prism 47, and the acousto-optic deflector 48
Thus, the optical deflection is performed so as to correspond to the desired exposure pattern.

As the acousto-optic element used for the acousto-optic deflector 48, for example, an acousto-optic element made of tellurium oxide (TeO ₂ ) is suitable. Then, the laser beam LB optically deflected by the acousto-optic deflector 48.
₂ is emitted from the deflection optical system OD via the wedge prism 49.

The wedge prisms 47 and 49 allow the laser light LB ₂ to enter the grating surface of the acousto-optic device of the acousto-optic deflector 48 so as to satisfy the Bragg condition, and the acousto-optic deflector 48 causes the laser light LB ₂ to enter. It has a function of preventing the horizontal height of the beam from changing even if LB _{2 is} optically deflected. In other words, the wedge prisms 47 and 49 and the acousto-optic deflector 48 are arranged such that the grating surface of the acousto-optic element of the acousto-optic deflector 48 satisfies the Bragg condition for the laser beam LB ₂ and is emitted from the deflection optical system OD. It is arranged so that the horizontal height of the laser light does not change.

Further, a driving driver 50 for driving the acousto-optic deflector 48 is attached to the acousto-optic deflector 48, and the driving driver 50 has a voltage controlled oscillator (VCO). Oscillato
r) The high frequency signal from 51 is supplied after being modulated with a sine wave. At the time of exposing the photosensitive layer, a signal according to a desired exposure pattern is input from the voltage control oscillator 51 to the driving driver 50, and the driving driver 50 drives the acousto-optic deflector 48 according to this signal. Thus, the laser beam LB ₂ is optically deflected in accordance with the desired wobbling.

Specifically, for example, the frequency is 194.1k.
When address information is added to the groove by wobbling the groove at Hz, for example, a high frequency signal having a center frequency of 224 MHz is generated at a frequency of 19
A sine wave signal is supplied from the voltage controlled oscillator 51 to the driving driver 50 with a control signal of 4.1 kHz.

In response to this signal, the driving driver 50 drives the acousto-optic deflector 48 to change the Bragg angle of the acousto-optic element of the acousto-optic deflector 48, whereby the frequency of 194.1 kHz. The laser beam is optically deflected so as to correspond to the wobbling. As a result, optical deflection was performed so that the spot position of the laser light focused on the photosensitive layer oscillated in the radial direction of the master substrate 11 at a frequency of 194.1 kHz and an amplitude of ± 9 nm.

Here, the polarization beam splitter PBS is
The S-polarized light is reflected and the P-polarized light is transmitted, and the optically deflected laser beam LB ₂ is S-polarized light and is reflected by the PBS.

Since the laser beam LB ₁ emitted from the first modulation optical system OM1 passes through the λ / 2 wave plate HWP, the polarization direction is rotated by 90 °, so P
It is polarized and passes through PBS.

In the examples described later, the numerical aperture NA of the objective lens is 0.9. Tellurium oxide (TeO ₂ ) was used for the acousto-optic elements of AOM1 and AOM2. The signal supplied from the input terminal through the drivers 25 and 26 is a space position signal of 2-7 modulation when forming a pit, and is a DC (direct current) signal of a constant level when forming a groove.

Further, in this example, the modulation optical systems OM1 and O
The optical lenses of M2 include condenser lenses L11 and L2.
The focal length of 1 was 80 mm, the focal lengths of the collimating lenses L12 and L22 were 100 mm, and the focal length of the magnifying lens L3 of the moving optical table 40 was 50 mm.

The exposure condition in the optical recording apparatus having the above-mentioned structure is that the laser power is 0.3 with respect to the wobble groove.
0 mJ / m, pit laser power is 0.25 mJ / m
On the substrate 11 for a master, a pit modulation, that is, a 2-7 modulation space position signal by the first modulation optical system OM1 and a DC modulation signal by the second modulation optical system OM2 are set to a track pitch of 0.32 μm. The photosensitive layer 12 was subjected to spiral pattern exposure.

As described with reference to FIGS. 1A to 1C described above, in the case of the pit edge detection method, 2-7 modulation is usually used.
The density (pit duty) in the direction along the recording track of pits and in the circumferential direction in the case of a disk-shaped medium is 50%. The push-pull signal amplitude ratio is proportional to the pit duty. That is, in the case of pit edge detection with a pit duty of 50%, the push-pull signal amplitude is 50
%. When detecting the pit position, the pit duty becomes 22.7%, and the push-pull signal amplitude further decreases to 22.7%.

However, in the present invention, as described above, the pit 3 is formed by the space position detection method.
, The average pit duty becomes 77.8% and the push-pull signal amplitude can be kept at 77.3%.

Further, as described with reference to FIG. 1E, the space length of the space position detection system is set to 0.5.
The average pit duty is 8 when T space length is used.
It becomes 4.2 to 89.4%. Space length from 1T to 0.5
By selecting an appropriate value of T, the pit duty can be substantially set in a wide range of 68.3 to 89.4%, and stable reproduction of tracking servo and space position detection becomes possible.

Then, after performing the above-mentioned pattern exposure,
The master substrate 11 is placed on the turntable of the developing machine so that the photosensitive layer 12 is on the upper side, and is rotated so that the surface of the master substrate 11 is horizontal. In this state,
A developing solution is dropped on the photosensitive layer 12 to develop the photosensitive layer 12, and a concavo-convex pattern based on a recording signal is formed in the signal forming area, which is used for manufacturing the optical recording / reproducing medium described in FIG. 4A. The master is formed.

Then, after this, the optical recording / reproducing medium on which the concavo-convex pattern that is the reverse of the concavo-convex pattern formed by the pattern exposure and developing process by the above-mentioned optical recording device is formed by the manufacturing process described in FIGS. A manufacturing stamper, in this case a so-called mother stamper, is formed, and the mother stamper is further subjected to an injection molding method or 2
By the P method or the like, a substrate for an optical recording / reproducing medium made of a light-transmitting resin such as polycarbonate is molded by injection molding in Examples described later.

Then, the thickness of the molded substrate is 1.1 mm.
On the signal forming surface thereof, a reflection layer 5 made of Al alloy or the like, a first dielectric layer 6 made of ZnS—SiO ₂ or the like, G
A recording layer 7 made of a phase change material made of eSbTe alloy or the like and a second dielectric layer 8 made of ZnS—SiO ₂ or the like are sequentially formed by sputtering or the like. After that, an ultraviolet curable resin is applied on the second dielectric layer 5 by a spin coating method, and the ultraviolet curable resin is irradiated with ultraviolet rays to be cured to form a protective layer 9 having a thickness of 0.1 mm. To do.

1 and 2 through the manufacturing process as described above.
As described above, an optical recording / reproducing medium of, for example, a DVR format in which pits and wobbling grooves are formed by the space position detecting method according to the present invention is formed.

The evaluation of the reproduction characteristics of the concavo-convex pattern of the optical recording / reproducing medium thus formed was carried out by the wavelength λ = 406n.
m is used, and an optical recording / reproducing apparatus equipped with an optical system having a numerical aperture NA = 0.85 is used. A schematic configuration of this device is shown in FIG.

In FIG. 6, 61 is the wavelength λ = 406 nm.
Shows a light source such as a semiconductor laser, and the laser beam emitted from this is collimated by the collimator lens 62,
The grating 63 divides the beam into three beams of 0th order light (main beam) and ± 1st order light (sub beam). These three beams (P-polarized light) pass through the polarization beam splitter 64 and the quarter-wave plate 65 as circularly polarized light, and as described above with reference to FIG. 3, the numerical aperture NA = 0.8.
By the optical pickup 66 composed of the objective lens 5
The light is focused on a predetermined recording track of the optical recording / reproducing medium 10. The central spot of the main beam is used for recording / reproducing recorded information, and the optical spot of the sub beam is used for detecting tracking error. 68 is an optical recording / reproducing medium 10
Shows a rotating means for rotating as shown by an arrow b. A solid line d indicates the rotation axis of the optical recording / reproducing medium 10.

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 made incident on the combination lens 71 and the lens 74.

The laser light incident on the combination lens 71 is incident on the photodiode 72 through a lens which gives astigmatism to the laser beam, is converted into an electric signal corresponding to the intensity of the beam, and is converted into a servo signal (focus error). Signal and tracking error signal) are output to the servo circuit. The photodiode 72 has a divided detector 73 (A to H). The return light of the main beam is a four-divided detector A located at the center of the detector 73.
To D, and the return light of the sub beam enters E to H located on both sides of the detector 73.

The laser beam reflected by the polarization beam splitter 70 is incident on the other photodiode 75 via the lens 74. The photodiode 75 has a detector 76 (G), and the polarization beam splitter 7
The laser light reflected at 0 is detected.

The signals A to H output by the detectors A to H are subjected to addition and subtraction processing as described below in a predetermined circuit system (not shown) to output a predetermined signal. In this example, a differential push-pull (DP) using the above-mentioned three laser beams arranged and irradiated at a predetermined interval is used.
A tracking servo signal was obtained by the P: Differential Push-Pull method. That is, reproduction 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). The optical recording / reproducing apparatus having such a configuration evaluated the above-described optical recording / reproducing medium according to the present invention in the following examples.

[Embodiment] In the following example, the space position detection method is used in which the space length is 1T, and the pit depth d is changed by changing the thickness of the photosensitive layer made of photoresist. 17, 23,
Optical recording / reproducing media A to E having a thickness of 34, 47, and 55 nm were produced. Further, the pit width w was changed to 130, 155, 170, and 190 nm by changing the cutting exposure power of each optical recording / reproducing medium, that is, the exposure power in the modulation optical system OM1 described in FIG. The track pitch p is 32 as described above.
It was set to 0 nm. Table 1 below shows the pit signal amount in each example. The refractive index n used to obtain the phase depth x (= λ / d · n) is 1.48 (the refractive index of the material of the protective layer 9 shown in FIG. 3), and the wavelength λ of the reproducing incident light is as described above. As 406 nm.

[0095]

[Table 1]

As is apparent from Table 1, stable tracking servo could not be performed on the optical recording / reproducing media A and E. However, stable tracking servo could be performed on the entire surfaces of the optical recording / reproducing media B, C, and D.

Further, in the area where the pit signal for space position detection of 2-7 modulation can be stably reproduced, the pit width of the optical recording / reproducing media B, C and D is 130 nm or more.
It was in the range of 0 nm or less. In the region where the pit width is 190 nm, the recorded signal of the pit due to the space position detection cannot be stably reproduced due to the influence of crosstalk between adjacent tracks. That is, in this case, the pit phase depth is λ /
The ratio of the pit width to the track pitch is 0.406 or more and 0.594 or more.
It can be seen that the signal can be reproduced well in the following cases.

Next, in the case where the space length is equivalent to 0.5T in the space position detection method, the pit depth is 17 nm, 20 nm, 23 nm, 34 nm, 47 by changing the photoresist depth in the same manner.
nm and 53 nm optical recording / reproducing media F to K were manufactured.
Further, by changing the cutting exposure power of each optical recording / reproducing medium, that is, the exposure power in the modulation optical system OM1 described with reference to FIG.
It was changed to 0, 155, 170 and 190 nm. The track pitch p is 320 nm as described above. Table 2 below shows the pit signal amount in each example. The refractive index n used to obtain the phase depth x (= λ / d · n) is 1.48 (the refractive index of the material of the protective layer 9 shown in FIG. 3), and the wavelength λ of the reproducing incident light is as described above. As 406 nm.

[0099]

[Table 2]

In Table 2 above, the optical recording / reproducing medium F is used.
Could not obtain a stable tracking servo. Stable tracking servo could be obtained over the entire surface of the optical recording / reproducing media G to K. Further, in the area where the 2-7 modulation space position detection can be stably reproduced, the pit width of the optical recording / reproducing media G to K is 130 nm.
It was 170 nm or less. In the region where the pit width is 190 nm, the space position detection cannot be stably reproduced due to the influence of crosstalk between adjacent tracks. That is,
In this case, the pit phase depth is λ / 13.7.
It can be seen that when 1n or more and λ / 5.18n or less and the ratio of the pit width to the track pitch is 0.406 or more and 0.531 or less, a good reproduction signal can be obtained.

As described above, the DVR track pitch of 0.32 μm is only about 4/3 of the cutoff frequency track pitch (0239 μm), which is less than 3/2 (0.32 / 0. 239 = 1.339)
Therefore, a sufficient tracking servo signal amplitude (push-pull signal amplitude) cannot be obtained.

However, as described above, even if the track pitch is narrow, the pit depth is 23 nm or more in an optical recording / reproducing medium in which pits are recorded with the space length corresponding to 1T by space position detection.
7 nm or less, that is, the phase depth x is λ / 11.93n ≦ x ≦ λ / 5.84n, and the ratio of the pit width w to the track pitch p is 0.406 ≦ w / p ≦ 0.531. Good reproduction characteristics of the pit signal could be realized when the optimum pit shape was adopted.

Further, pits by the 1-7 modulation space position detection (pit duty 68.3%) and the EFM modulation space position detection (pit duty 78.8%) are performed in the above pit shape,
Good reproduction characteristics of the pit signal were realized.

Furthermore, in space position detection,
In an optical recording / reproducing medium having pits recorded with a space length equivalent to 0.5T, the phase depth x is set to λ / 13.71n ≦ x ≦ 5.18n, and the ratio of the pit width w to the track pitch p is 0. By setting .406 ≦ w / p ≦ 0.531, good pit signal reproduction characteristics could be realized.

Further, in this case, space position detection of 1-7 modulation (pit duty 84.2%), EFM
Modulation space position detection (pit duty 8
The pits according to each method of 9.4%) were formed in the above-mentioned pit shape, and good reproduction characteristics of the pit signal could be realized.

That is, in the space position detection method, even when the space length is set to 1T, that is, when the pit duty is set to 68.3 to 78.8%, the space length is set to 0.5T and the pit duty is set to 0.5T. 8
It can be seen that stable reproduction of tracking servo and space position detection is possible even when the ratio is 4.2 to 89.4%. Pit duty is 78.8
In the area of more than 8% and less than 84.2%, a similarly stable reproduction signal can be obtained by selecting a suitable space length value of 0.5T to 1T in the space position detection method.

Further, when the space length is changed from 1T to 0.5T, the range of the phase depth x of the pits which can reproduce a good pit signal is, as described above, λ / 11.93.
From n ≦ x ≦ λ / 5.84n, λ / 13.71n ≦ x ≦
Since it is 5.18n, it can be seen that the range of the optimum phase depth is widened. That is, the space length is 1T to 0.5T
It is considered that the optimum pit phase depth range for obtaining stable reproduction characteristics gradually widens as the space length is made smaller, when selected during. Therefore, the space length is 1
When the range is from T to 0.5T, the phase depth of the pit is λ
It is understood that a stable reproduction signal can be obtained by appropriately selecting in the range of /13.71n≦x≦λ/5.18n.

Further, as shown in Japanese Patent Application No. 2001-199303, the area where the address information of the wobbled groove can be stably reproduced, that is, the optical recording / reproducing media B, C, D,
G / H / I groove width of 130 nm or more and 190 nm or less, recording / reproducing with 1-7 modulation on the surface near the incident side of the reproducing light in this case, reproducing with jitter of 10% or less on the entire surface of the disk It was possible to realize good recording and reproducing characteristics.

In the example described with reference to FIG.
DVR of PIC (P ermanent I nformation and C ontrol
It is also possible to provide the pits of the space position detection method in the (Data) area, that is, in the area generally defined like the TOC. Also, when forming only pits for narrow track pitch space position detection,
Similarly, good recording / reproducing characteristics could be obtained.

Further, it can be used for a format in which pits and grooves are mixed. When the track pitch is set to 3/2 times or more the track pitch corresponding to the cutoff frequency, a sufficient push-pull signal can be obtained even if the pit format is the edge detection format described above. In the present invention, the track pitch is 4/3 or more and 3/2 or less of the track pitch of the cutoff frequency.

As described above, in the present invention, as in the case of adopting the land-groove recording system, the track density is doubled to the conventional one, and good reproduction characteristics of the pit signal can be realized. It is possible to provide an optical recording / reproducing medium in which grooves are formed in a mixed manner with pits on the side closer to the reading surface, and good reproduction characteristics of a pit signal and recording / reproduction characteristics of a groove can be compatible without changing a focus point.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-mentioned examples, and the material constitution of each layer such as a recording layer made of a phase change material is changed. Needless to say, various other modifications can be made within the scope of the present invention, such as the case where a magneto-optical recording layer or a dye material layer is used as the recording layer, the substrate material and the structure.

Further, the information is not limited to the recorded information, and an optical recording / reproducing medium having a function of recording / reproducing a signal or both recording / reproducing of an information and a signal, a stamper for manufacturing an optical recording / reproducing medium, and an optical recording / reproducing. It can also be applied to a device.

[0114]

As described above, according to the present invention, by recording pits by space position detection, it is possible to avoid halving of the tracking servo signal amplitude (push-pull signal amplitude) in the pit portion.
Even in an optical recording / reproducing medium such as a VR-ROM which has a narrow track pitch of about 0.32 μm with the increase in recording density, a sufficient tracking servo signal amplitude can be obtained and good pit information recording / reproducing characteristics can be maintained. can do.

Further, since the space position detection system can be formed by a simple method of only controlling the signal for pattern exposure of the photosensitive layer when manufacturing the optical recording / reproducing medium, the manufacturing process is complicated. Can be manufactured with good productivity by using the optical recording device having the conventional structure.

Further, according to the present invention, there is provided an optical recording / reproducing medium having a format in which pits and grooves are mixed and in which pits and grooves are formed with the same track pitch, or an optical recording / reproducing apparatus using the same. can do.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a pit recording method.

FIG. 2 is an explanatory diagram of an example of an optical recording / reproducing medium.

FIG. 3 is a schematic enlarged cross-sectional view of an example of an optical recording / reproducing medium.

FIG. 4A is a manufacturing process diagram of an example of a stamper for manufacturing an optical recording / reproducing medium. FIG. 3B is a manufacturing process diagram of an example of a stamper for manufacturing an optical recording / reproducing medium. C is a manufacturing process diagram of an example of a stamper for manufacturing an optical recording / reproducing medium.

FIG. 5 is a configuration diagram of an example of an optical recording device.

FIG. 6 is a block diagram of an example of an optical recording / reproducing apparatus.

[Explanation of symbols]

1 substrate, 3 pits, 4 grooves, 5 reflective layers, 6
First dielectric layer, 7 recording layer, 8 second dielectric layer, 9
Protective layer, 10 optical recording / reproducing medium, 11 master substrate, 12 photosensitive layer, 13 pit pattern, 13n reverse pit pattern, 14 groove pattern, 14n
Inverted groove pattern, 15 stamper, 16 mother stamper, 20 light source, 21 electro-optic modulator, 22
Analyzer, 24 Photodetector, 25, Driving driver, 26 Driving driver, 40 Moving optical table, 4
7 Wedge prism, 48 Acousto-optic deflector, 49
Wedge prism, 50 driving driver, 51 voltage controlled oscillator, 52 objective lens, 54 optical pickup 61 light source, 62 collimating lens, 63 grating, 64 polarization beam splitter (PBS), 6
5 1/4 wavelength plate, 66 optical pickup, 67 magnetic head, 68 rotating means, 70 polarization beam splitter, 71 combination lens, 72 photodiode, 73 detector, 74 lens, 75 photodiode, 76 detector

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/26 511 G11B 7/26 511 11/105 521 11/105 521F 521H 546 546D (72) Inventor Shu Ikuhiro Tanaka 30 Takara, Niida, Nakata-cho, Tome-gun, Miyagi Prefecture, Kaganosakai, Sony Miyagi Corporation F-term (reference) 5D029 WA02 WA26 WB11 WB17 WD01 WD10 5D075 AA03 CC21 EE03 FG18 GG06 GG02 GG02 GG14 BB14 BB07 BB07 BB07 BB07 BB14

Claims (27)

[Claims] 1. An optical recording / reproducing medium in which pits corresponding to recording information are formed along recording tracks, and the recording format of the pits is a format in which the irregularities of the pit position detection format are reversed. The track pitch of the pits is 4/3 or more and 3/2 or less of the track pitch of the cutoff frequency corresponding to the wavelength λ of the reproducing light for reproducing the record information of the optical recording / reproducing medium and the numerical aperture NA of the objective lens. An optical recording / reproducing medium characterized by comprising: 2. When the wavelength of the reproducing light for reproducing the recorded information of the optical recording / reproducing medium is λ, and the refractive index of the medium from the incident side of the reproducing light of the optical recording / reproducing medium to the pit is n. And the phase depth x of the pits is λ / 13.71n ≦ x ≦ λ / 5.18n, and the ratio of the width w of the pits to the track pitch p of the pits is 0.406 ≦ The optical recording / reproducing medium according to claim 1, wherein w / p ≦ 0.531. 3. The pit modulation method is one of a 1-7 modulation method, a 2-7 modulation method and an EFM modulation method, and the pit modulation method is characterized in that: The optical recording / reproducing medium described. 4. The optical recording according to claim 1, wherein the density of the pits in the direction along the extension direction of the recording track is 68.3% or more and 89.4% or less. Reproduction medium. 5. The optical recording / reproducing medium is formed by forming at least a recording layer and a protective layer on a molded substrate, and a groove is formed on the substrate to reproduce recorded information of the optical recording / reproducing medium. 2. The surface near the incident side of the reproducing light is the groove surface of the groove, and the recording information is recorded only on the groove surface.
2. The optical recording / reproducing medium according to 2, 3 or 4. 6. The optical recording / reproducing medium according to claim 5, wherein the groove is a wobbled groove. 7. The optical recording / reproducing medium according to claim 5, wherein the track pitch of the groove is the same as the track pitch of the pit. 8. The optical recording / reproducing medium according to claim 5, 6 or 7, wherein a recording track on which the pit and the groove are formed is formed so as to draw a spiral trajectory. 9. The pit and the groove are formed in a mixed manner, and the pit and the groove are formed in a mixed manner.
The optical recording / reproducing medium according to. 10. A stamper for manufacturing an optical recording / reproducing medium for manufacturing an optical recording / reproducing medium in which pits corresponding to recording information are formed along recording tracks, and a recording format of a pit pattern corresponding to the pits. Is a format in which the irregularities of the pit position detection format are reversed, and the track pitch of the pit pattern is the wavelength λ of the reproducing light for reproducing the recorded information of the optical recording / reproducing medium and the numerical aperture NA of the objective lens. A stamper for manufacturing an optical recording / reproducing medium, which has a cut-off frequency of 4/3 or more and 3/2 or less of a track pitch. 11. The wavelength of the reproducing light for reproducing the recorded information of the optical recording / reproducing medium is λ, and the refractive index of the medium from the incident side of the reproducing light of the optical recording / reproducing medium to the pit is n.
Then, the phase depth x ′ of the pit pattern is set to λ / 13.71n ≦ x ′ ≦ λ / 5.18n, and the width w ′ of the pit pattern and the track pitch p of the pit pattern are set. The stamper for manufacturing an optical recording / reproducing medium according to claim 10, wherein the ratio with respect to 'is 0.406≤w' / p'≤0.531. 12. The pit modulation method is one of a 1-7 modulation method, a 2-7 modulation method, and an EFM modulation method.
Or a stamper for producing an optical recording / reproducing medium according to item 11. 13. The density of the pit pattern in a direction along the extension direction of the recording track is 68.3% or more 8
12. The stamper for manufacturing an optical recording / reproducing medium according to claim 10, wherein the stamper is 9.4% or less. 14. The stamper according to claim 10, wherein a groove pattern is formed on the stamper.
Or a stamper for producing an optical recording / reproducing medium according to item 13. 15. The groove pattern is formed as a wobbled groove pattern.
A stamper for manufacturing an optical recording / reproducing medium according to item 1. 16. The stamper for manufacturing an optical recording / reproducing medium according to claim 14, wherein the track pitch of the groove pattern is the same as the track pitch of the pit pattern. 17. The stamper for manufacturing an optical recording / reproducing medium according to claim 14, wherein the pit pattern and the groove pattern are formed in a spiral locus. 18. The stamper for manufacturing an optical recording / reproducing medium according to claim 14, 15, 16 or 17, wherein the pit pattern and the groove pattern are formed in a mixed manner. 19. An optical recording / reproducing apparatus using an optical recording / reproducing medium in which pits corresponding to recording information are formed along recording tracks, wherein a recording format of the pits of the optical recording / reproducing medium is pit position detection. The pits of the optical recording / reproducing medium have a track pitch of λ and the numerical aperture NA of the objective lens for reproducing the information recorded on the optical recording / reproducing medium. An optical recording / reproducing apparatus having a cut-off frequency of 4/3 or more and 3/2 or less of the track pitch. 20. The wavelength of the reproducing light for reproducing the recorded information of the optical recording / reproducing medium is λ, and the refractive index of the medium from the incident side of the reproducing light of the optical recording / reproducing medium to the pit is n.
Then, the phase depth x of the pit is λ / 13.71n ≦ x ≦ λ / 5.18n, and the ratio of the width w of the pit to the track pitch p of the pit is 0. 20. The optical recording / reproducing apparatus according to claim 19, wherein .406 ≦ w / p ≦ 0.531. 21. The modulation system of the pits of the optical recording / reproducing medium is 1-7 modulation system, 2-7 modulation system or EF.
21. The optical recording / reproducing apparatus according to claim 19, wherein the optical recording / reproducing apparatus is one of the M modulation methods. 22. The density of the pits of the optical recording / reproducing medium in the direction along the extension direction of the recording track is 6
21. The optical recording / reproducing apparatus according to claim 19, wherein the content is set to 8.3% or more and 89.4% or less. 23. The optical recording / reproducing medium is formed by forming at least a recording layer and a protective layer on a molded substrate, and a groove is formed on the substrate to reproduce recorded information of the optical recording / reproducing medium. The surface near the incident side of the reproducing light is the groove surface of the groove, and the recording information is recorded only on the groove surface.
The optical recording / reproducing apparatus according to 9, 20, 21 or 22. 24. The optical recording / reproducing apparatus according to claim 23, wherein the groove of the optical recording / reproducing medium is a wobbled groove. 25. The optical recording / reproducing apparatus according to claim 23, wherein a track pitch of the groove of the optical recording / reproducing medium is the same as a track pitch of the pit. 26. The recording track in which the pits and the grooves of the optical recording / reproducing medium are formed is formed so as to draw a spiral track. Optical recording / reproducing device. 27. The optical recording / reproducing apparatus according to claim 23, 24, 25 or 26, wherein the pits and the grooves of the optical recording / reproducing medium are formed in a mixed manner.