JP2001216655A - Optical recording medium, master disk for manufacturing optical recording medium and recording and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily take interchangeability between with a standardized conventional optical recording medium while realizing the high density of recording. SOLUTION: The modulation and demodulation system of a signal to be recorded on a recording track and that of a wobble signal are made same as a modulation and demodulation system in the standardized conventional optical recording medium. A ratio of the period length of the shortest mark of the signal to be recorded on the recording track to the length of one period of the wobble signal is nearly equalized with a ratio of the period length of the shortest mark of the signal to be recorded on the recording track of the standardized conventional optical recording medium to the length of one period of the wobble signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium in which a wobbling groove is formed along a recording track and a wobble signal from the wobbling groove is reproduced when a signal is recorded on the recording track. The present invention relates to an optical recording medium production master used when producing a novel optical recording medium, and a recording / reproducing method for recording and / or reproducing signals using such an optical recording medium.

[0002]

2. Description of the Related Art As an optical recording medium, an optical disk formed in a disk shape and optically recorded and / or reproduced has been put to practical use. As such an optical disk, for example, a compact disk (CD),
There is a read-only optical disk in which a pit string corresponding to a recording signal is previously formed on a disk substrate. Here, the mark length of each pit constituting the pit row is a length obtained by standardizing a signal to be recorded at a predetermined bit interval T. That is, the mark length of each pit constituting the pit row is an integral multiple of the bit interval T, and the mark length of the shortest pit is, for example, three times the bit interval T (3T).

Further, as an optical disk, for example, an optical disk to which a signal can be written such as an optical disk (hereinafter, referred to as a CD-R) used in a so-called compact disk recordable system has been put to practical use. The CD-R is a write-once optical disc in which signals are recorded and reproduced using an organic dye-based recording material.

The CD-R has a wobbling groove formed along a recording track. here,
The wobbling groove is a guide groove formed so as to meander at a predetermined cycle. The guide groove itself has a signal component by meandering the guide groove. Note that the guide groove is a groove formed along a recording track in order to facilitate tracking servo by, for example, a push-pull method.

In a CD-R, sector information including FM-modulated absolute time information is recorded as a signal (wobble signal) based on the wobbling groove (ATIP: Absolute Time In Pregroove). That is, in a compact disk recordable system using a CD-R as a recording medium, a wobble signal having a carrier of, for example, 22.05 kHz is detected by a recording / reproducing light spot focused on a wobbling groove, and the absolute time is measured. A data string containing information is detected by FM demodulating the signal.

[0006] As described above, in the method of recording sector information including absolute time information as a wobble signal, signals can be continuously recorded. This is advantageous in achieving compatibility between the two. That is, in the method in which the address information is arranged at the head of each sector, the absolute time information and the recording signal are recorded in a time-division manner, and the recorded signal becomes discontinuous. Although it is difficult to achieve compatibility with the read-only optical disc, a method of recording sector information including absolute time information as a wobble signal can easily achieve compatibility with a read-only optical disc.

As an optical disk having a wobbling groove, in addition to the above-described CD-R, a magneto-optical disk such as a mini disk (MD: Mini Disc) for recording and reproducing signals by utilizing a magneto-optical effect. Also, an optical disk in which a signal can be rewritten, such as a phase-change optical disk in which a signal is recorded / reproduced using a phase change of a recording film. However, in the case of a mini disk, address information (ADIP: Address In Pregroove) is recorded as a wobble signal.

When recording or reproducing signals on or from these optical disks, tracking is performed on a wobbling groove to detect a wobble signal having a carrier wave of, for example, 22.05 kHz, and this wobble signal is subjected to FM (Frequequent).
(ncy Modulation) demodulation detects sector information including absolute time information. Then, a recording signal (EFM signal) subjected to EFM modulation (8 → 14 modulation) is recorded on a recording track corresponding to the groove of the target absolute time, and the recording signal recorded here is reproduced.

[0009]

Incidentally, in the above-mentioned optical disc, the recording density is high so that more information can be recorded while keeping the same outer diameter as that of a standardized existing optical disc. Is being actively promoted. Specifically, examples of an optical disk with a higher recording density include DVD-R and DVD-R.
W, DVD + RW and the like have been proposed.

However, in these optical disks,
The recording signal is the EFM in the existing optical disc described above.
It is recorded as a signal modulated by EFM + modulation (8 → 16 modulation) different from modulation. Further, the wobble signal also has a frequency of 22.0
Unlike 5 kHz FM modulation, DVD-R and DVD-R
In the RW, as a single frequency SIN wave wobble signal, D
In VD + RW, it is recorded as a PM (Phase Modulation) modulated wobble signal.

For this reason, a recording / reproducing system using an optical disk with a higher recording density as a recording medium can record / reproduce signals on / from these optical disks while also recording / reproducing signals onto / from an existing optical disk. It was difficult to make it possible, that is, to have so-called compatibility.

As described above, when considering compatibility between a plurality of optical disks having different recording signal modulation / demodulation methods and wobble signal modulation / demodulation methods, a plurality of modulation / demodulation circuits are required in correspondence with the respective optical disk modulation / demodulation methods. It is conceivable that a recording / reproducing system is configured by overlappingly mounting the plurality of modulation / demodulation circuits. However, it is not desirable from the viewpoint of cost to mount a plurality of modulation / demodulation circuits in an overlapping manner.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and achieves compatibility with a standardized conventional optical recording medium while realizing a high recording density. To provide an optical recording medium that can be easily taken, and an optical recording medium manufacturing master used when manufacturing such an optical recording medium, and a signal using such an optical recording medium. It is an object of the present invention to provide a recording / reproducing method for performing recording and / or reproducing.

[0014]

In an optical recording medium according to the present invention, a wobbling groove is formed along a recording track, and when a signal is recorded on the recording track, a wobble signal from the wobbling groove is reproduced. Optical recording medium. In this optical recording medium, while the modulation and demodulation method of the signal recorded on the recording track and the modulation and demodulation method of the wobble signal are the same as the modulation and demodulation method of the standardized optical recording medium, the recording density is the same as that of the existing optical recording medium. The ratio between the cycle length of the shortest mark of the signal recorded on the recording track and the length of one cycle of the wobble signal is recorded on the recording track of the standardized optical recording medium. The ratio of the cycle length of the shortest mark of the signal to the length of one cycle of the wobble signal is substantially equal.

According to this optical recording medium, the modulation / demodulation method of the signal recorded on the recording track and the modulation / demodulation method of the wobble signal are the same as those of the standardized existing optical recording medium. The ratio between the cycle length of the shortest mark of the signal recorded on the optical disc and the length of one cycle of the wobble signal is determined by the cycle length of the shortest mark of the signal recorded on the recording track of the existing optical recording medium and the wobble signal. Is almost equal to the length of one cycle of the optical recording medium, so that the linear velocity at the time of scanning the recording track is different from that at the time of recording / reproducing a signal to / from an existing optical recording medium. A wobble signal can be reproduced in the same manner as in a medium, and a signal can be recorded and reproduced in a recording track in the same manner as in an existing optical recording medium.

That is, in this optical recording medium, it is possible to easily achieve compatibility with the existing optical recording medium while making the recording density higher than that of the standardized existing optical recording medium. It is possible.

In the master for manufacturing an optical recording medium according to the present invention, a wobbling groove is formed along a recording track, and a wobble signal from the wobbling groove is reproduced when a signal is recorded on the recording track. This is an optical recording medium manufacturing master used when manufacturing an optical recording medium, and has an uneven pattern corresponding to a wobbling groove formed on the optical recording medium. An optical recording medium manufactured using this master for manufacturing an optical recording medium uses a modulation / demodulation method for a signal recorded on the recording track and a modulation / demodulation method for the wobble signal in a standardized optical recording medium. The recording density is higher than that of the standardized optical recording medium, and the ratio between the period length of the shortest mark of the signal recorded on the recording track and the length of one period of the wobble signal is the same as that of the standardized optical recording medium. Is an optical recording medium in which the ratio of the cycle length of the shortest mark of the signal recorded on the recording track of the standardized optical recording medium to the length of one cycle of the wobble signal is substantially equal.

If an optical recording medium is manufactured using this master for manufacturing an optical recording medium, the recording density can be made higher than that of a standardized existing optical recording medium while maintaining the same density with the existing optical recording medium. An optical recording medium compatible with the above can be manufactured.

Further, in the recording / reproducing method according to the present invention, a wobbling groove is formed along a recording track, and a wobble signal from the wobbling groove is reproduced when a signal is recorded on the recording track. And using a plurality of optical recording media having different recording densities while using the same modulation and demodulation method of a signal recorded on the recording track and the same modulation and demodulation method of the wobble signal, and recording on the recording tracks of the plurality of optical recording media. The ratio between the cycle length of the shortest mark of the signal to be written and the length of one cycle of the wobble signal is set substantially equal to each other, and the linear velocity when scanning the recording tracks of the plurality of optical recording media is changed for each optical recording medium. The recording and / or reproduction of the signal is performed differently.

According to this recording / reproducing method, while maintaining compatibility between a plurality of optical recording media having different recording densities, signal recording and / or signal recording / reproducing is performed on each of the plurality of optical recording media having different recording densities. Reproduction can be performed appropriately.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. Here, a signal recording / reproducing is performed using an organic dye-based recording material.
An example in which the present invention is applied to DR will be described.

The CD-R includes a disk substrate 1 made of polymethyl methacrylate (PMMA), polycarbonate (PC), or the like, which is formed in a disk shape, as shown in FIG. A recording layer 2 formed by spin coating an organic dye-based recording material is formed thereon. On the recording layer 2, for example, gold (Au), silver (Ag), or the like is formed to form a reflective film 3.
Further, a protective layer 4 is formed on the reflective film 3 by spin-coating, for example, an ultraviolet curable resin. The above configuration shows an example of an optical disk to which the present invention is applied, and it goes without saying that the present invention is not limited to the above example.

In this CD-R, as shown in a plan view of a main part in FIG. 2, a wobbling groove 5 which is a meandering guide groove is formed in a disk substrate 1, for example, in a spiral shape. Then, the wobbling groove 5 of the recording layer 2
Is set as the recording track,
This recording track is subjected to a signal (EF
M signal) is recorded.

The wobbling groove 5 is formed so as to meander (wobble) at a predetermined cycle, and the sector information including the absolute time information which is FM-modulated by the wobbling causes the ATIP (Absolute Time).
In Pregroove) Recorded as a wobble signal.

By the way, the CD-R to which the present invention is applied is
The ratio between the cycle length of the shortest mark of the EFM signal recorded on the recording track and the length of one cycle of the ATIP wobble signal is determined by the shortest mark of the standardized EFM signal recorded on the recording track of the existing CD-R. The ratio between the period length and the length of one period of the ATIP wobble signal is substantially equal. The CD-R to which the present invention is applied is compatible with the standardized existing CD-R while maintaining the compatibility with the existing CD-R.
The recording density is higher than that of -R.

Hereinafter, regarding this, existing CD-Rs (single-density CD-Rs) in which CD-Rs (double-density CD-Rs, quadruple-density CD-Rs) to which the present invention is applied are standardized. A specific description will be given while comparing with FIG.

In a standardized single-density CD-R which is an existing CD-R, the clock frequency of the EFM signal is 4.32 MHz, and the frequency of the ATIP wobble signal is 22.05 kHz. And Clo of the EFM signal
ck frequency / ATIP wobble signal frequency is 195.9
It becomes 2.

Here, EFM in a single density CD-R
By applying the modulation and demodulation of the signal and the modulation and demodulation of the ATIP wobble signal as they are, the double density CD-R and the quadruple density CD-R
Considering that the modulation and demodulation of the EFM signal and the modulation and demodulation of the ATIP wobble signal are performed, the bandwidth of the EFM signal and the bandwidth of the ATIP wobble signal of the double-density CD-R and the quadruple-density CD-R are changed to that of the single-density CD-R. Of the EFM signal and the band of the ATIP wobble signal.

The double density CD-R and 4 to which the present invention is applied
In the double-density CD-R, in order to increase the recording density,
The track pitch, which is the interval between recording tracks, is reduced, and the linear density is increased. Accordingly, in the case of the double-density CD-R and the quadruple-density CD-R, the linear velocity at the time of scanning the recording track is such that the recording track of the single-density CD-R that is the standardized existing CD-R is scanned. It is set to be lower than the linear velocity at the time of execution.

As described above, the linear velocity at the time of scanning the recording track is set to be lower than the linear velocity at the time of scanning the recording track of the single-density CD-R. In a CD-R, the band of the EFM signal and the AT
To match the band of the IP wobble signal with the band of the EFM signal and the band of the ATIP wobble signal in the single density CD-R, the period length of the shortest mark of the EFM signal and A
It is necessary to shorten the length of one cycle of the TIP wobble signal at the same rate.

In other words, in the double density CD-R and the quadruple density CD-R, the band of the EFM signal and the band of the ATIP wobble signal are changed to the EFM in the single density CD-R.
In order to match the band of the signal and the band of the ATIP wobble signal, the period length of the shortest mark of the EFM signal and the ATIP
The ratio of the length of one cycle of the wobble signal to the length of one cycle CD-
It is necessary to make the ratio of the period length of the shortest mark of the R EFM signal to the length of one period of the ATIP wobble signal substantially equal.

Explaining with specific numerical values, the clock frequency of the EFM signal in the standardized single-density CD-R, which is an existing CD-R, is 4.
32 MHz. Here, since the clock frequency of the EFM signal is six times the frequency of the shortest mark (3T) signal, the shortest mark signal frequency of the single-density CD-R EFM signal is 720 kHz. In addition, 1-times density CD-R
, The ATIP wobble signal frequency is 22.05 kHz as described above.

Here, the linear velocity in a single density CD-R is set to 1.20 m / sec. At such a linear velocity, the single-density CD is adjusted so that the band of the EFM signal and the band of the ATIP wobble signal have the above-mentioned values.
In -R, the length (ML in FIG. 2) of the shortest mark (3T) is set to about 0.83333 μm, and the length of one cycle of the wobble signal (WL in FIG. 2) is set to about 54.422 μm. In a single-density CD-R, the wavelength λ of light used for recording and reproducing signals is set to 780 nm, the numerical aperture NA of the objective lens is set to 0.45, and the track pitch (TP in FIG. 2) is set. Is set to 1.60 μm.

Considering the cycle length of the shortest mark (MFL in FIG. 2), the cycle of the shortest mark is a repetition of the shortest mark (3T) and the shortest land (3T). Twice as large as Accordingly, the period length of the shortest mark in a single density CD-R is about 1.
66666 μm.

As described above, the standardized existing CD-
In a single-density CD-R that is R, the length of one cycle of the wobble signal (WL in FIG. 2) is about 54.422 μm, and the cycle length of the shortest mark (MFL in FIG. 2) is about 1.66666 μm. is there. Therefore, the ratio of the cycle length of the shortest mark to the length of one cycle of the wobble signal (one cycle length of the wobble signal / the shortest mark cycle length) is about 32.
653.

For such a single-density CD-R,
In order to perform modulation and demodulation of an EFM signal and modulation and demodulation of an ATIP wobble signal in the same manner as a single-density CD-R while increasing the recording density, a double-density CD-to which the present invention is applied.
In the R and quadruple-density CD-Rs, the ratio of the cycle length of the shortest mark to the length of one cycle of the wobble signal (one cycle length of the wobble signal / the shortest mark cycle length) is the same as that of a single-density CD-R. It is set to be about 32.653.

Specifically, the double density C to which the present invention is applied
In DR, the linear velocity is set to 0.88 m / sec, the length of the shortest mark is set to about 0.61111 μm, and the length of one cycle of the wobble signal is set to about 39.909 μm. In a double-density CD-R, the wavelength λ of light used for recording and reproducing signals is set to 780 nm, the numerical aperture NA of the objective lens is set to 0.55, and the track pitch is set to 1.10 μm. Have been.

In such a double-density CD-R, the length of one cycle of the wobble signal is about 39.909 μm as described above.
m, and the period length of the shortest mark is about 1.22222 μm, which is twice the length of the shortest mark. Therefore, the ratio of the cycle length of the shortest mark to the length of one cycle of the wobble signal (one cycle length of the wobble signal / the shortest mark cycle length) is:
This is about 32.653, which is the same as a standardized existing CD-R, ie, a single density CD-R. Therefore, in this double-density CD-R, modulation and demodulation of an EFM signal and ATIP similar to that of a single-density CD-R are performed while increasing the recording density.
Recording and reproduction of signals by modulation and demodulation of wobble signals are possible.

Further, a quadruple density CD-R to which the present invention is applied
In, the linear velocity is set to 0.60 m / sec,
The length of the shortest mark is set to about 0.41666 μm, and the length of one cycle of the wobble signal is set to about 27.211 μm. In a quadruple-density CD-R, the wavelength λ of light used for recording and reproducing signals is 780 nm, and the numerical aperture of the objective lens is N.
A is set to 0.60, and the track pitch is set to 0.80 μm.

In such a quadruple-density CD-R, the length of one cycle of the wobble signal is about 27.211 μm as described above.
m, and the period length of the shortest mark is about 0.833332 μm, which is twice the length of the shortest mark. Therefore, the ratio of the cycle length of the shortest mark to the length of one cycle of the wobble signal (one cycle length of the wobble signal / the shortest mark cycle length) is:
This is about 32.653, which is the same as a standardized existing CD-R, ie, a single density CD-R. Therefore, in this quad-density CD-R, modulation and demodulation of an EFM signal and ATIP similar to that of a single-density CD-R are performed while increasing the recording density.
Recording and reproduction of signals by modulation and demodulation of wobble signals are possible.

The ratio between the cycle length of the shortest mark and the length of one cycle of the wobble signal described above is the ratio between the spatial frequency of the shortest mark and the spatial frequency of the wobble signal, that is,
It can also be considered as a ratio between the number of marks existing per unit length of the recording track and the wobble period.

In a standardized single-density CD-R that is an existing CD-R, the ratio of the spatial frequency of the shortest mark to the spatial frequency of the wobble signal (the shortest mark signal spatial frequency /
The wobble signal spatial frequency is about 32.653, and even in a double-density CD-R to which the present invention is applied, the ratio of the shortest mark spatial frequency to the wobble signal spatial frequency (shortest mark signal spatial frequency / wobble signal space). Frequency)
The density is set to about 32.653 as in the case of a CD-R having a single density. Further, a quadruple density CD-R to which the present invention is applied
In this case, the ratio of the spatial frequency of the shortest mark to the spatial frequency of the wobble signal (the spatial frequency of the shortest mark signal / the spatial frequency of the wobble signal) is about 3 as in the case of a single-density CD-R.
It is set to 2.653.

In the case of the double density CD-R as described above, 0.1.
If the recording track is scanned at a linear velocity of 88 m / sec, the band of the EFM signal and the band of the ATIP wobble signal are changed to the band of the EFM signal of the single density CD-R (clock frequency: 4.32 MHz, shortest mark). Signal frequency:
720 kHz) and the band of the ATIP wobble signal (2
2.05 kHz), so that the modulation and demodulation of the EFM signal and the modulation and demodulation of the ATIP wobble signal can be used to record and reproduce the signal as in the case of the single density CD-R.

In a quadruple-density CD-R as described above, if the recording track is scanned at a linear velocity of 0.60 m / sec, the bandwidth of the EFM signal and the bandwidth of the ATIP wobble signal are increased by one time. It is possible to match the band of the EFM signal of the density CD-R (clock frequency: 4.32 MHz, shortest mark signal frequency: 720 kHz) and the band of the ATIP wobble signal (22.05 kHz).
Modulation and demodulation of AFM signal and ATI similar to double density CD-R
Recording and reproduction of the signal by modulation and demodulation of the P wobble signal can be performed.

Next, a method for manufacturing a CD-R to which the present invention is applied will be described with reference to a specific example.

When manufacturing a CD-R to which the present invention is applied, first, an optical recording medium manufacturing master having an uneven pattern corresponding to the wobbling groove 5 is manufactured.

When manufacturing an optical recording medium manufacturing master having a concavo-convex pattern corresponding to the wobbling groove 5,
First, a disk-shaped glass substrate whose surface is polished with high precision is washed and dried. Then, a photoresist as a photosensitive material is applied on the glass substrate.

Next, the glass substrate coated with the photoresist is placed in a laser cutting device 10 as shown in FIG.
The photoresist 51 applied on the glass substrate 50 is exposed to light, and a latent image corresponding to the wobbling groove 5 is formed on the photoresist 51.

The laser cutting device 10 shown in FIG.
Has a He—Cd laser that emits a laser beam having a wavelength λ of 442 nm as the light source 11. Then, the photoresist 51 is exposed using light emitted from the light source 11 (hereinafter, referred to as an exposure beam B1), and a latent image corresponding to the wobbling groove 5 is formed.

The glass substrate 50 coated with the photoresist 51 is mounted on a rotary drive. Then, when exposing the photoresist 51, the glass substrate 50 is rotated at a predetermined rotation speed by a rotation driving device as shown by an arrow A in FIG. 3 so that the entire surface of the photoresist 51 is exposed in a desired pattern. , And the moving optical table 52 moves the arrow B in FIG.
Are translated at a predetermined moving speed in the direction indicated by.

Specifically, when a master for manufacturing an optical recording medium for a double density CD-R is manufactured, the glass substrate 50
Is rotated so that the linear velocity at which the exposure beam B1 moves on the photoresist 51 is 0.88 m / sec. Also, each time the glass substrate 50 makes one rotation, the moving optical table 52 moves 1.10 μm in the direction indicated by the arrow B in FIG.
The moving operation is performed by m (for the track pitch).

Exposure beam B1 emitted from light source 11
Is reflected by the mirrors 12 and 13 and is guided horizontally and parallel on the moving optical table 52. Then, an exposure beam B1 guided horizontally and parallel to the moving optical table 52
Is optically deflected by the deflection optical system 14.

Here, the deflection optical system 14 is for performing optical deflection on the first exposure beam, and has an acousto-optical deflector (AOD: Acousto Optical Deflector) 15.
And two wedge prisms 16 and 17 that satisfy the lattice plane and the Bragg condition of the acousto-optic element of the AOD 15 and are arranged so that the horizontal height of the exposure beam does not change. Then, the exposure beam B1 incident on the deflection optical system 14 is incident on the AOD 15 via the wedge prism 16, and is subjected to optical deflection (wobbling) by the AOD 15 so as to correspond to a desired exposure pattern. Then, the exposure beam B1 optically deflected by the AOD 15 is emitted from the deflection optical system 14 via the wedge prism 17.

As the acousto-optic element of the AOD 15, for example, tellurium oxide (TeO ₂ ) is used. Also, AOD
A drive driver 18 for driving the AOD 15 is attached to 15. At the time of exposing the photoresist 51, a control signal S1 (22.0) is supplied to the driving driver 18 from the voltage frequency controller (VCO 19).
A high-frequency signal S2 (center frequency 244 MHz) FM-modulated by 5 kHz absolute time information) is supplied. The driving driver 18 responds to the high-frequency signal S2.
Drives the AOM 15. Specifically, AOD1
In 5, the Bragg angle changes according to the control signal S1 of 22.05 kHz, whereby the exposure beam B1 is subjected to optical deflection according to the absolute time information.

The exposure beam B 1, which has been optically deflected by the polarization optical system 14 in accordance with a desired exposure pattern, is given a predetermined beam diameter by the magnifying lens 20, and
The light is reflected by 1 and guided to the objective lens 22, and is condensed on the photoresist 51 by the objective lens 22. At this time, the exposure beam B1 is condensed on the photoresist 51 applied to the glass substrate 50 which is rotated and driven by the rotation driving device. Then, with the exposure beam B1 condensed on the photoresist 51,
The moving optical table 52 is moved. As a result, the latent image corresponding to the irradiation locus of the exposure beam B1 is converted into a latent image corresponding to the wobbling groove 5 by the photoresist 51.
To be formed.

Incidentally, the exposure beam B1 is applied to the photoresist 5
The objective lens 22 for condensing the light on the light source 1 has a numerical aperture N in order to form a latent image having a finer pattern.
It is preferable that A is large. Specifically, the objective lens 22
A lens having a numerical aperture NA of about 0.9 is preferable.

When irradiating the photoresist 51 with the exposure beam B1, the beam diameter of the exposure beam B1 is changed by the magnifying lens 20 if necessary.
The effective numerical aperture for the objective lens 22 is adjusted. Thereby, the spot diameter of the exposure beam B1 focused on the surface of the photoresist 51 can be changed. Here, a lens having a focal length of 80 mm was used as the magnifying lens 20.

The above description has been made with reference to the case where a master for manufacturing an optical recording medium for a double density CD-R is described as an example. In the case of manufacturing, a high frequency signal S2 having a center frequency of 224 MHz is used.
To a control signal S1 (ATIP) having a frequency of 22.05 kHz.
A wobble signal) is FM-modulated and supplied from the VCO 19 to the driving driver 18. Then, this high-frequency signal S
The exposure beam B1 is optically deflected by driving the AOM 15 by the driving driver 18 according to (2). Then, the photoresist 51 is irradiated with the optically deflected exposure beam B1.
And a latent image corresponding to the wobbling groove 5 is formed.

However, when a master for manufacturing an optical recording medium for a quadruple-density CD-R is manufactured, the glass substrate 50 is moved at a linear velocity at which the exposure beam B1 moves on the photoresist 51 to 0.60 m / sec. The rotation operation is performed by the rotation drive device so that Further, when producing a master for producing an optical recording medium for a quadruple-density CD-R, the
Each time the optical table 52 rotates, the moving optical table 52 is moved by an arrow B in FIG.
Is moved by 0.80 μm (for the track pitch) in the direction indicated by.

As described above, when a latent image corresponding to the wobbling groove 5 is formed on the photoresist 51,
Next, the glass substrate 50 is placed on a rotary drive of a developing machine such that the surface on which the photoresist 51 is applied is the upper surface. Then, while rotating the glass substrate 50 by rotating the rotation driving device, a developing solution is dropped on the photoresist 51 to perform a developing process. Thus, an uneven pattern corresponding to the wobbling groove 5 is formed on the glass substrate 50.

Next, a conductive film made of Ni or the like is formed on the concave / convex pattern by electroless plating, and then the glass substrate on which the conductive film is formed is attached to an electroforming apparatus.
A plating layer made of Ni or the like is formed on the conductive film by electroplating so as to have a thickness of about 300 ± 5 μm. Thereafter, the plating layer is peeled off, and the peeled plating is washed with acetone or the like to remove the photoresist remaining on the surface on which the concavo-convex pattern has been transferred.

According to the above steps, an optical recording medium manufacturing master made of plating to which the concave / convex pattern formed on the glass substrate 50 has been transferred, that is, the optical recording medium on which the concave / convex pattern corresponding to the wobbling groove 5 has been formed. A master for production (a so-called stamper) is completed.

The master for producing an optical recording medium is a master for producing an optical recording medium to which the present invention is applied. That is, the master for manufacturing an optical recording medium is an optical recording medium manufacturing master used when manufacturing an optical disk having a wobbling groove 5 formed along a recording track, and has irregularities corresponding to the wobbling groove 5. The groove pattern, which is a pattern, is formed in a spiral shape.

Next, a transparent resin such as polycarbonate is injection-molded using the optical recording medium production master prepared as described above, and the surface shape of the optical recording medium production master is transferred to the wobbling groove 5. The disk substrate 1 on which is formed is manufactured. The disk substrate 1 is, for example, a resin molded product formed into a disk having a thickness of 1.2 mm and a diameter of 120 mm, and has a refractive index of, for example, 1.58.

Next, on the disk substrate 1 manufactured as described above, for example, 2% by weight of TFP
After dropping the (tetrafluoropropanol) solution, the disk substrate 1 is rotated at a speed of 400 rpm for 20 seconds, and shaken off to dry. Then, on the disk substrate 1,
For example, a recording material substantially consisting of a cyanine dye alone is applied (formed into a film) by a spin coating method or the like to form the recording layer 2.

Further, after a silver thin film having a thickness of, for example, 100 nm is formed as a reflective film 3 on the recording layer 2 by sputtering, an ultraviolet curable resin layer having a thickness of, for example, 10 μm is applied by spin coating. The protective layer 4 is formed by irradiating the ultraviolet curable resin with ultraviolet rays to cure the resin.
To form Thereby, a CD-R to which the present invention is applied is completed.

A double-density CD-R was actually manufactured by the above-described manufacturing method and evaluated. Hereinafter, the results of the evaluation will be described.

As a double-density CD-R for evaluation, the track pitch is 1.10 μm, the width of the wobbling groove 5 is 0.4 μm, and the depth of the wobbling groove 5 is 180.
A double density CD-R set to nm was produced. In this double-density CD-R for evaluation, as exemplified in the above-described manufacturing method, the disk substrate 1 was manufactured by injection molding using an optical recording medium manufacturing master, and the recording layer 2 was made of an organic dye system. Using a recording material, a silver thin film having a thickness of 100 nm is formed as a reflective film 3 and an ultraviolet curable resin is cured to form a 10 μm thick silver film.
Of the protective layer 4.

In this double-density CD-R for evaluation, the wobble amplitude of the wobbling groove 5 is changed for each area, and the wobble amplitude is set to ± 20 nm, ± 24 nm, and ± 28 nm.
Various types of wobble amplitude are provided.

The double-density CD-R for evaluation manufactured as described above is wobbled while rotating at a linear velocity of 0.88 m / sec using a recording / reproducing apparatus 30 as shown in FIG. An EFM signal was recorded on a dye recording film in the wobbling groove 5 at a desired position while tracking the groove 5 and demodulating an FM-modulated wobble signal having a frequency of 22.05 kHz and obtaining absolute time information.
The EFM recorded on the double density CD-R for evaluation
The signal was reproduced using the recording / reproducing device 30.

The recording / reproducing apparatus 30 shown in FIG. 4 includes a spindle motor 31 for rotating a double-density CD-R for evaluation at a linear velocity of 0.88 m / sec. Also,
The recording / reproducing apparatus 30 includes a semiconductor laser 32 that emits laser light having a wavelength λ of about 780 nm, and a numerical aperture NA of 0.1.
The optical system includes 55 objective lenses 33, a quarter-wave plate 34, a beam splitter 35, a collimator lens 36, and a two-segment photodetector 37.

The two-divided photodetector 37 comprises light receiving elements 37A and 37B divided corresponding to the radial direction of the double density CD-R rotated by the spindle motor 31. The output signal from the light receiving element 37A is
The signal is supplied to the addition circuit 39 and the subtraction circuit 40 via 8A, and the output signal from the light receiving element 37B is supplied to the addition circuit 39 and the subtraction circuit 40 via the amplifier 38B.

In the recording / reproducing apparatus 30, the output signal of the amplifier 38A is Sa and the output of the amplifier 38B is S
b, (Sa + Sb)
Is generated, and the HF signal (EFM signal) is extracted from the output terminal 41. Further, the push-pull signal (Sa-Sb) is generated by the subtraction circuit 40, and this push-pull signal is extracted from the output terminal 42.

When demodulating an FM-modulated wobble signal (frequency 22.05 kHz) by the recording / reproducing apparatus 30, a push-pull signal is extracted from the output terminal 42. This push-pull signal contains a tracking error and is supplied to a tracking servo circuit (not shown). In the tracking servo circuit, a tracking error signal is generated by, for example, synchronous detection of the push-pull signal.

The push-pull signal extracted from the output terminal 42 is supplied to a band-pass filter 43. Then, the output signal of the bandpass filter 43 is supplied to the waveform shaping circuit 44.

The output signal of the waveform shaping circuit 44 is supplied to an FM decoder 45. Thus, the absolute time information is extracted from the output terminal 46.

The waveform shaping circuit 44 generates a clock signal and supplies it to the spindle servo circuit 47. The spindle servo circuit 47 controls the spindle motor 31 according to the clock signal, and controls the double-density CD-R mounted on the spindle motor 31 to 0.88 m / sec.
The rotation operation is performed stably at the linear velocity of c.

When recording / reproducing was performed on a double-density CD-R for evaluation using the recording / reproducing apparatus 30 as described above, the wobble amplitude of the wobbling groove 5 was ± 2.
In each region of 0 nm, ± 24 nm, and ± 28 nm, F
The M-modulated wobble signal is a standardized CD-R
Thus, demodulation was performed stably by the demodulation method for a 1-density CD-R, and absolute time information was appropriately obtained.

The HF extracted from the output terminal 41
When the signal (EFM signal) is demodulated in the same manner as the one-density CD-R EFM signal demodulation, the wobble amplitude is ± 20.
The jitter of the signal recorded in the wobbling groove 5 of 2 nm is 29.0 ns, and the wobble amplitude amount is ± 24.
The jitter of the signal recorded in the wobbling groove 5 of 2 nm was 29.8 ns, and the wobble amplitude was ± 28.
The jitter of the signal recorded in the wobbling groove 5 of 2 nm was 29.4 ns. When the recorded EFM signal is reproduced, the jitter is reduced to 3 by the Orange Book.
The standard is set to 5 ns or less.
Double-density CD-Rs sufficiently satisfy this standard.

As described above in detail, in the CD-R to which the present invention is applied, the ratio of the cycle length of the shortest mark to the length of one cycle of the wobble signal (one cycle length of the wobble signal / length of the shortest mark cycle). Is almost equal to the standardized existing CD-R, so that only the linear velocity at the time of scanning the recording track is changed, and the band of the EFM signal and the ATI
The band of the P wobble signal is standardized by the existing CD-R
In the band of the EFM signal and the band of the ATIP wobble signal. Therefore, in the CD-R to which the present invention is applied, while increasing the recording density,
It is possible to record / reproduce a signal by modulating / demodulating an EFM signal and modulating / demodulating an ATIP wobble signal in the same manner as an existing standardized CD-R, thereby facilitating compatibility with an existing standardized CD-R. Can be taken.

In other words, the CD-R to which the present invention is applied
And an existing standardized CD-R are optical disks on which a wobbling groove is formed along a recording track and a wobble signal from the wobbling groove is reproduced when a signal is recorded on the recording track. An optical disc having different recording densities while using the same modulation and demodulation method for a signal recorded on a recording track and the modulation and demodulation method for a wobble signal. Then, the CD-R to which the present invention is applied
And the standardized existing CD-R, the ratio between the cycle length of the shortest mark of the signal recorded on the recording track and the length of one cycle of the wobble signal is substantially equal.

Therefore, the CD to which the present invention is applied
-R and a standardized existing CD-R are used as a recording medium, the recording and reproduction of signals can be performed by changing the linear velocity when scanning these recording tracks. The recording / reproducing of the signal can be appropriately performed while maintaining the compatibility between them, without mounting the modulation / demodulation circuit in the recording / reproducing apparatus redundantly. That is, if a CD-R to which the present invention is applied and a standardized existing CD-R are used as recording media, highly convenient recording with compatibility can be performed without increasing the apparatus cost. It is possible to build a playback system.

Further, in the CD-R to which the present invention is applied as described above, sector information including absolute time information is recorded as a wobble signal, and the signal can be recorded continuously. Therefore, compatibility can be easily obtained even with a read-only optical disk in which signals are continuously recorded.

Although the present invention has been described above with respect to an example in which the present invention is applied to a CD-R in which a signal is recorded / reproduced using an organic dye-based recording material, the present invention is not limited to the above example. Not a mini disc (MD)
For example, a magneto-optical disc that records and reproduces a signal using a magneto-optical effect, a phase-change optical disc that records and reproduces a signal by using a phase change of a recording film, and the like, in which any signal can be rewritten. It is applicable to optical disks of the type.

Also in this case, the modulation and demodulation method of the signal recorded on the recording track and the modulation and demodulation method of the wobble signal are the same as those of the standardized existing optical disk, and the period of the shortest mark of the signal recorded on the recording track is set. By making the ratio between the length and the length of one cycle of the wobble signal substantially equal to that of an existing standardized optical recording medium, the linear velocity at the time of scanning a recording track can be reduced so that the signal can be recorded and reproduced on an existing optical disc. The wobble signal can be reproduced in the same manner as in the existing optical disc, and the recording and reproduction of the signal can be performed on the recording track in the same manner as in the existing optical disc, only by making a difference from the case of performing the operation.

[0086]

As described above in detail, according to the optical recording medium of the present invention, if the linear velocity when scanning the recording track is different from that when recording and reproducing signals on the existing optical recording medium. By simply performing this, the wobble signal can be reproduced in the same manner as in the existing optical recording medium, and the signal can be recorded and reproduced in the recording track in the same manner as in the existing optical recording medium. That is, in this optical recording medium, while increasing the recording density compared to the existing standardized optical recording medium,
It is possible to easily achieve compatibility with the existing optical recording medium.

When an optical recording medium is manufactured by using the optical recording medium manufacturing master according to the present invention, the existing optical recording medium can be made to have a higher recording density than a standardized existing optical recording medium, and to have a higher recording density. An optical recording medium compatible with a recording medium can be manufactured.

Further, according to the recording / reproducing method according to the present invention, while maintaining compatibility between a plurality of optical recording media having different recording densities, a signal is transmitted to each of the plurality of optical recording media having different recording densities. Recording and / or reproduction can be appropriately performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a CD-R to which the present invention is applied.

FIG. 2 is a plan view schematically showing a recording track of the CD-R.

FIG. 3 is a view showing a step of producing an optical recording medium producing master used in producing the CD-R;
FIG. 4 is a schematic view showing a laser cutting device used for exposing and forming a concavo-convex pattern corresponding to the wobbling groove of FIG.

FIG. 4 is a schematic diagram showing a recording / reproducing apparatus for recording / reproducing a signal to / from the CD-R.

[Explanation of symbols]

1 disk substrate, 2 recording layer, 3 reflective film, 4
Protective layer, 5 wobbling groove, 10 laser cutting device, 11 light source, 14 deflection optical system, 18 drive driver, 19 voltage frequency controller, 22 objective lens, 30 recording / reproducing device, 3
1 spindle motor, 32 semiconductor laser, 37
2 split photodetector, 45 FM decoder, 50 glass substrate, 51 photoresist, 52 moving optical table

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihiro Akimori 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo F-term in Sony Corporation (reference) 5D090 BB01 BB04 CC01 CC04 CC11 CC14 DD02 EE02 FF08 FF11 GG03 GG32 HH01

Claims (5)

[Claims] 1. An optical recording medium in which a wobbling groove is formed along a recording track and a wobble signal from the wobbling groove is reproduced when a signal is recorded on the recording track. The modulation density is higher than that of the standardized optical recording medium while the modulation and demodulation scheme of the signal to be performed and the modulation and demodulation scheme of the wobble signal are the same as those of the standardized optical recording medium. The ratio between the cycle length of the shortest mark of the signal recorded on the track and the length of one cycle of the wobble signal is the same as the cycle length of the shortest mark of the signal recorded on the recording track of the standardized optical recording medium. An optical recording medium characterized in that the ratio is substantially equal to the length of one cycle of a signal. 2. The signal recorded on the recording track is E
The wobble signal is a signal to which FM modulation has been applied.
A signal containing M-modulated absolute time information or a signal containing address information, and is a value obtained by dividing the length of one cycle of the wobble signal by the cycle length of the shortest mark of a signal recorded on the recording track. 2. The optical recording medium according to claim 1, wherein is set to about 32.653. 3. The recording layer according to claim 1, wherein a recording layer is formed using an organic dye-based recording material, and a signal recorded on the recording track is recorded as a change in reflectance of the recording material. Optical recording medium. 4. A wobbling groove is formed along a recording track, and light used for manufacturing an optical recording medium from which a wobble signal from the wobbling groove is reproduced when a signal is recorded on the recording track. A master for manufacturing a recording medium, wherein an uneven pattern corresponding to a wobbling groove formed on the optical recording medium is formed, wherein the optical recording medium has a modulation / demodulation method of a signal recorded on the recording track and the wobble. While the modulation and demodulation method of the signal is the same as the modulation and demodulation method in the standardized optical recording medium, the recording density is higher than that of the standardized optical recording medium, and the shortest mark of the signal recorded on the recording track is The ratio between the cycle length of the wobble signal and the length of one cycle of the wobble signal is recorded on the recording track of the standardized optical recording medium. A ratio of the cycle length of the shortest mark of the signal to be read to the length of one cycle of the wobble signal is substantially equal. 5. An optical recording medium in which a wobbling groove is formed along a recording track and a wobble signal from the wobbling groove is reproduced when a signal is recorded on the recording track, wherein the wobbling signal is recorded on the recording track. Using the same modulation and demodulation method for the signal to be recorded and the modulation and demodulation method for the wobble signal, using a plurality of optical recording media having different recording densities, the cycle length of the shortest mark of the signal recorded on the recording track of the plurality of optical recording media And the length of one cycle of the wobble signal are made substantially equal, and the signal recording and / or recording is performed by changing the linear velocity when scanning the recording tracks of the plurality of optical recording media for each optical recording medium.
Or a recording / reproducing method characterized by performing reproduction.