JP2001331975A - Optical recording medium, master disk for manufacture of optical recording medium and device for optical recording and reproducing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain reproducing characteristics of signals recorded in recording tracks and reproducing characteristics of wobble signals detected from wobbling grooves both in a high level while realizing higher recording density. SOLUTION: In the optical recording medium, wobbling grooves are formed along the recording tracks, and signals are recorded and/or reproduced in specified recording tracks while wobble signals are detected from the wobbling grooves. The wobbling grooves are formed as wobbling in a nearly trapezoid or square pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam for forming and / or reproducing a signal on a predetermined recording track while detecting a wobble signal from the wobbling groove. It relates to a recording medium. Further, the present invention also provides an optical recording medium manufacturing master used when manufacturing such an optical recording medium, and
The present invention relates to an optical recording / reproducing apparatus for recording and / or reproducing signals on 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 recording and / or reproducing signals has been put to practical use. As such an optical disk, for example, a CD (Compact Disc) or a CD-ROM
There is a read-only optical disk such as a (CD-Read Only Memory) in which pit strings corresponding to recording signals are formed in advance on a disk substrate. Optical disks include optical disks on which signals can be written, such as an optical disk (hereinafter, referred to as a CD-R) used in a so-called compact disk recordable system.

A CD-R is a write-once optical disk on which signals are recorded and reproduced using an organic dye-based recording material, and has a wobbling groove formed along a recording track.

[0004] Here, the wobbling groove is a guide groove formed so as to meander (wobble) at a predetermined period. By making the pregroove which is the guide groove meander, a signal is transmitted to the pregroove itself. The components are added. The pre-groove is a groove formed in advance on a disk substrate along a recording track in order to facilitate tracking servo by, for example, a push-pull method.

In the CD-R, sector information including absolute time information modulated by FM is recorded as a signal based on the wobbling groove, that is, a so-called wobble signal. This is called ATIP (Absolute Time In Pregroove). . That is, in the CD-R, a light beam is condensed on a wobbling groove, the reflected light is detected, a wobble signal having a carrier of, for example, 22.05 kHz is detected, and the wobble signal is FM-demodulated. Thus, recording and reproduction are performed while detecting sector information including absolute time information.

As described above, by recording sector information including absolute time information as a wobble signal, it is possible to continuously record a signal, and it is possible to use a read-only optical disc on which a signal is continuously recorded. This is advantageous for compatibility. That is, in the method of recording the address information 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. It is difficult to obtain compatibility with a read-only optical disc, which is described above, but by recording sector information including absolute time information as a wobble signal as in ATIP, it is possible to obtain compatibility with a read-only optical disc. Can be easily obtained.

As an optical disk having such a wobbling groove, in addition to the above-described CD-R,
Signals such as a magneto-optical disk that records and reproduces signals using a magneto-optical effect such as a mini-disc (MD: Mini Disc) and a phase-change optical disk that records and reproduces signals using a phase change of a recording film. Optical disks that can be rewritten. Also, for example, an ADIP (Ad-IP) in which address information is recorded as a wobble signal like a mini-disc.
Dress In Pregroove).

When recording and reproducing signals on and from these optical discs, a wobble signal having a carrier wave of, for example, 22.05 kHz is detected while tracking the wobbling groove, and the wobble signal is FM-demodulated. Detect sector information including absolute time information. Then, a signal subjected to EFM modulation (8 → 14 modulation), that is, a so-called EFM signal, is recorded on a recording track corresponding to a target absolute time, and the recorded signal recorded here is reproduced.

[0009]

In the above-mentioned optical disk, for example, a track pitch is set so that more information can be recorded while keeping the same outer diameter as that of a standardized existing optical disk. Or narrow
2. Description of the Related Art Increasing the recording density by increasing the linear density in the track direction has been actively performed. For example, as an optical disc with such a high recording density, DVD
-R, DVD-RW, DVD + RW and the like.

Here, in the optical disk having the above-described wobbling groove, the wobbling groove is
Meandering sinusoidally along the recording track (wobbling)
It is formed so that. In addition, by increasing the wobble amplitude of the wobbling groove, the wobble C / N is improved, and sector information including absolute time information can be easily detected.

However, in such an optical disc, when the wobble amplitude of the wobbling groove increases, the jitter of the signal recorded in the wobbling groove deteriorates, which adversely affects the reproduction characteristics of an EFM signal such as an RF signal. Was given. further,
The deterioration of the jitter accompanying the increase in the wobble amplitude amount becomes more remarkable when the track pitch is narrowed or when the linear density in the track direction is increased.

For this reason, it is very difficult to improve the recording density of an optical disk having a wobbling groove, and when reproduction is performed by a conventional optical recording / reproducing apparatus, an increase in jitter, a decrease in C / N, and the like occur. Inviting me
There is a problem that a stable reproduction operation cannot be performed.

Accordingly, the present invention has been proposed in view of such a conventional situation. While realizing a high recording density, the present invention has been developed in consideration of the reproduction characteristics of a signal recorded on a recording track and the wobbling groove. It is an object of the present invention to provide a high-quality optical recording medium in which reproduction characteristics of a detected wobble signal are compatible with a high dimension. Also, an optical recording medium manufacturing master used when manufacturing such an optical recording medium,
It is another object of the present invention to provide an optical recording / reproducing method for recording and / or reproducing a signal with respect to such an optical recording medium.

[0014]

According to the optical recording medium of the present invention which achieves the above object, a wobbling groove is formed along a recording track, and a wobble signal is detected from the wobbling groove while a wobbling signal is detected. An optical recording medium on which signal recording and / or reproduction is performed, wherein the wobbling groove is wobbled in a substantially trapezoidal shape.

In this optical recording medium, the wobbling groove is wobbled in a substantially trapezoidal shape along the recording track. Therefore, the wobble C / N is excellent with respect to the wobble amplitude of the wobbling groove, and the wobble amplitude is improved. Since a sufficient wobble C / N can be obtained without increasing the amount, it is possible to suppress the deterioration of the jitter of the signal recorded on the recording track due to the increase in the wobble amplitude amount.

In the optical recording medium according to the present invention, a wobbling groove is formed along a recording track, and a signal is recorded and / or reproduced on a predetermined recording track while detecting a wobble signal from the wobbling groove. Wherein the wobbling groove is wobbled in a substantially rectangular shape.

In this optical recording medium, since the wobbling groove is wobbled in a substantially rectangular shape along the recording track, the wobble C / N is good with respect to the wobble amplitude of the wobbling groove, and the wobble amplitude is high. Since a sufficient wobble C / N can be obtained without increasing the amount, it is possible to suppress the deterioration of the jitter of the signal recorded on the recording track due to the increase in the wobble amplitude amount.

In the master for producing an optical recording medium according to the present invention which achieves this object, a wobbling groove is formed along a recording track, and a wobble signal is detected from the wobbling groove while a wobble signal is detected. An optical recording medium manufacturing master used when manufacturing an optical recording medium on which signal recording and / or reproduction is performed, wherein an uneven pattern corresponding to a wobbling groove formed on the optical recording medium is substantially It is characterized by being formed while being wobbled in a shape.

In this master for producing an optical recording medium, the concave / convex pattern corresponding to the wobbling groove formed on the optical recording medium is formed while being wobbled in a substantially trapezoidal shape. By using the optical recording medium, it is possible to manufacture an optical recording medium in which the wobbling groove is formed in a substantially trapezoidal shape along the recording track. Therefore, in the optical recording medium manufactured using the master for manufacturing an optical recording medium, the wobble C / N is good with respect to the wobble amplitude of the wobbling groove, and the wobble C / N is sufficient without increasing the wobble amplitude. Since N is obtained, it is possible to suppress the deterioration of the jitter of the signal recorded on the recording track due to the increase in the wobble amplitude.

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 signal is recorded and recorded on a predetermined recording track while detecting a wobble signal from the wobbling groove. And / or an optical recording medium manufacturing master used when manufacturing an optical recording medium on which reproduction is performed, wherein an uneven pattern corresponding to a wobbling groove formed on the optical recording medium is wobbled in a substantially rectangular shape. It is characterized by being formed.

In this master for producing an optical recording medium, an uneven pattern corresponding to a wobbling groove formed on the optical recording medium is formed while being wobbled in a substantially rectangular shape. By using the optical recording medium, an optical recording medium in which the wobbling groove is formed in a substantially rectangular shape along the recording track can be manufactured. Therefore, in the optical recording medium manufactured using the master for manufacturing an optical recording medium, the wobble C / N is good with respect to the wobble amplitude of the wobbling groove, and the wobble C / N is sufficient without increasing the wobble amplitude. Since N is obtained, it is possible to suppress the deterioration of the jitter of the signal recorded on the recording track due to the increase in the wobble amplitude.

According to another aspect of the present invention, there is provided an optical recording / reproducing apparatus including an optical recording medium having a wobbling groove formed along a recording track, and detecting a wobble signal from the wobbling groove of the optical recording medium. While recording a signal on a predetermined recording track and / or
Alternatively, in an optical recording / reproducing apparatus for performing reproduction, the optical recording medium is characterized in that a wobbling groove is wobbled in a substantially trapezoidal shape.

In this optical recording / reproducing apparatus, since the wobbling groove of the optical recording medium is wobbled in a substantially trapezoidal shape along the recording track, the wobble C / N is good with respect to the wobble amplitude of the wobbling groove. Thus, a sufficient wobble C / N can be obtained without increasing the wobble amplitude, so that the deterioration of the jitter of the signal recorded on the recording track due to the increase of the wobble amplitude can be suppressed.

Further, the optical recording / reproducing apparatus according to the present invention includes an optical recording medium having a wobbling groove formed along a recording track, and detects a wobble signal from the wobbling groove of the optical recording medium, and performs a predetermined operation. An optical recording / reproducing apparatus for recording and / or reproducing a signal on / from a recording track, wherein the optical recording medium has a wobbling groove wobbled in a substantially rectangular shape.

In this optical recording / reproducing apparatus, since the wobbling groove of the optical recording medium is wobbled in a substantially rectangular shape along the recording track, the wobble C / N is good with respect to the wobble amplitude of the wobbling groove. Thus, a sufficient wobble C / N can be obtained without increasing the wobble amplitude, so that the deterioration of the jitter of the signal recorded on the recording track due to the increase of the wobble amplitude can be suppressed.

[0026]

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

In the following description, a double density CD-R is taken as an example of an optical recording medium to which the present invention is applied.
The present invention can be applied to optical recording media other than double-density CD-Rs, and can be widely applied to optical recording media in which wobbling grooves are formed along recording tracks.

<Double density CD-R>
FIG. 1 is an enlarged cross-sectional view of a main part of the double-density CD-R.

This double-density CD-R includes a disk substrate 1 formed of a disk made of polymethyl methacrylate (PMMA), polycarbonate (PC), or the like.
On this disk substrate 1, a recording layer 2 formed by spin-coating an organic dye-based recording material is formed. Also,
On the recording layer 2, for example, gold (Au), silver (Ag), or the like is formed to form a reflective film 3. Further, on the reflective film 3, for example, an ultraviolet curable resin is spin-coated. Thus, the protective layer 4 is formed.

In this double-density CD-R, as shown 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. A portion corresponding to the wobbling groove 5 of the recording layer 2 is set as a recording track, and a signal (EFM signal) subjected to EFM modulation is recorded on this recording track. The wobbling groove 5 is meandering (wobbling) at a predetermined amplitude and at a constant period, so that sector information including FM-modulated absolute time information is stored in an ATIP (Absolute T
ime In Pregoove) Recorded as a wobble signal. FIG. 2 is an enlarged plan view showing a part of the recording area of the double density CD-R.

By the way, the double density CD to which the present invention is applied
In −R, as shown in FIG.
Are formed so as to meander (wobble) along a recording track in a substantially trapezoidal shape.

Further, a double density CD-R to which the present invention is applied
Then, as shown in FIG. 3, the wobbling groove 5 is
It may be formed so as to wobble in a substantially rectangular shape along the recording track.

The double density C to which the present invention is applied as described above
In the DR, as can be seen from the evaluation result described later, the wobbling groove 5 is wobbled in a substantially trapezoidal or substantially rectangular shape along the recording track. The wobble C / N is good, and the jitter of the signal (EFM signal) recorded in the wobbling groove 5 is good.

Therefore, the double density C to which the present invention is applied
In the DR, it is possible to obtain a sufficient wobble C / N without increasing the wobble amplitude, so that the jitter of the signal recorded in the wobbling groove 5 due to the increase in the wobble amplitude is reduced. Thus, the recording density can be greatly improved.

<Method of Manufacturing Double Density CD-R> Next, a method of manufacturing a double density CD-R to which the present invention is applied will be described.
This will be described with a specific example.

When manufacturing the double-density CD-R, first, an original master for manufacturing an optical recording medium having an uneven pattern corresponding to the wobbling groove 5 is manufactured.

When manufacturing the master for manufacturing an optical recording medium, 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 applied to a laser cutting device 1 as shown in FIG.
The latent image corresponding to the wobbling groove 5 is formed on the photoresist 51 by exposing the photoresist applied on the glass substrate 50.

The laser cutting device 10 includes, as the light source 11, a He-Cd laser that emits a laser beam having a wavelength λ of 442 nm. And this light source 11
The photoresist 51 is exposed to light using a laser beam (hereinafter, referred to as an exposure beam) emitted from the laser beam to form a latent image corresponding to the wobbling groove 5.

The glass substrate 50 coated with the photoresist 51 is attached to a rotary drive. Then, when exposing the photoresist 51, the glass substrate 50
The photoresist 51 is rotated at a predetermined rotational speed in a direction indicated by an arrow A in the drawing so as to be exposed in a desired pattern over the entire surface of the photoresist 51, and is moved by a moving optical table 52. The moving operation is performed in the direction indicated by the middle arrow B in parallel at a predetermined moving speed.

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

The exposure beam emitted from the light source 11 is guided horizontally and parallel to the moving optical table 52 via the mirrors 12 and 13. The exposure beam guided horizontally and parallel to the moving optical table 52 is transmitted to the deflection optical system 1.
4 provides optical deflection.

Here, the deflection optical system 14 is for performing optical deflection on the exposure beam so as to correspond to the wobbling of the wobbling groove 5, and an acousto-optic 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. The exposure beam that has entered the deflection optical system 14 enters 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 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. When the photoresist 51 is exposed, a voltage frequency controller (VOC: Voltage Controlled Oscillator) is supplied to the driving driver 18.
Supplies a high-frequency signal S2 (center frequency: 244 MHz) FM-modulated by the control signal S1 (22.05 kHz ATIP signal). The AOD 15 is driven by the driving driver 18 according to the high frequency signal S2. Specifically, in the AOD 15, the Bragg angle of the acousto-optic element changes according to the control signal S1, whereby the exposure beam is subjected to optical deflection according to the ATIP signal.

Here, in the deflection optical system 14, the control signal S1 (22.05 kHz) is used to wobble the wobbling groove 5 in a substantially trapezoidal shape along the recording track.
(ATIP signal) is superimposed on a fundamental wave (sinusoidal wobble) wobbled in a sine wave to form an ATIP signal (trapezoidal wobble) wobbled in a trapezoidal wave. Then, the high frequency signal S2 FM-modulated by the control signal S1 is supplied from the voltage controlled oscillator to the driving driver 18. The AOD 15 is driven by the driving driver 18 according to the high-frequency signal S2 to change the Bragg angle of the acousto-optic device of the AOD 15, whereby the light spot of the exposure beam condensed on the photoresist 51 is changed. Position is A
Based on the TIP signal, optical deflection is performed at a frequency of 22.05 kHz and an amplitude of about ± 20 nm so as to vibrate (trapezoidal wobble) in the radial direction of the glass substrate 50.

As described above, the fundamental wave (sine wave wobble)
And 2n + 1 harmonics (n is a natural number) which is a harmonic component
Are sequentially superimposed by an appropriate amount, whereby an ATIP signal (trapezoidal wobble) can be generated.

For example, as shown in FIG. 5, by superimposing an appropriate amount of the third harmonic on the fundamental wave, the fundamental wave +
Third harmonic superimposed wobble (1.2sinX + 0.18sin ³
X) is generated. And
Based on the ATIP signal Y1, the frequency 22.05k
The optical deflection is performed so as to vibrate (trapezoidal wobble) in the radial direction of the glass substrate 50 at a frequency of about Hz and an amplitude of about ± 20 nm. Thereby, a latent image corresponding to the trapezoidal wave wobble of the wobbling groove 5 can be formed on the photoresist 51.

Also, the third harmonic is applied by an appropriate amount to the fundamental wave.
By superimposing the 5th and 5th harmonics, the fundamental wave + 3rd harmonic
Harmonic and fifth harmonic superimposed wobbles (1.2 sinX + 0.
3 sin ^ThreeX + 0.1sin^FiveX) is an ATIP signal Y2
Generated. Then, based on the ATIP signal Y2,
To a frequency of 22.05 kHz and an amplitude of about ± 20 nm.
And vibrate in the radial direction of the glass substrate 50 (trapezoidal wave wobble).
Optical deflection. This allows for wobble
The latent image corresponding to the trapezoidal wave wobble of
It can be formed on the photoresist 51.

For comparison, a sine wave wobble (sin wave)
X) is shown in FIG.

The exposure beam, which has been optically deflected by the deflection optical system 14 so as to correspond to the trapezoidal wobble of the wobbling groove 5, has a predetermined beam diameter by the magnifying lens 20 and then has a mirror. The objective lens 54 is guided to the objective lens 54 through the
Is focused on the photoresist 51. At this time, the exposure beam is focused on the photoresist 51 applied to the glass substrate 50 which is rotated and driven by the rotation driving device. Then, while the exposure beam is focused on the photoresist 51, the moving optical table 52
Is moved. As a result, a latent image corresponding to the irradiation locus of the exposure beam is formed on the photoresist 51 as a latent image corresponding to the trapezoidal wave wobble of the wobbling groove 5.

The objective lens 22 for condensing the exposure beam on the photoresist 51 preferably has a large numerical aperture NA so that a latent image having a finer groove pattern can be formed. Specifically, a lens having a numerical aperture NA of about 0.9 is suitable as the objective lens 22.

When irradiating the photoresist 51 with the exposure beam as described above, the magnifying lens 2 may be used if necessary.
By changing the beam diameter of the exposure beam by 0, the effective numerical aperture for the objective lens 22 is adjusted. Thereby, the spot diameter of the exposure beam 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.

As described above, a latent image corresponding to the trapezoidal wave wobble of 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, by rotating this rotation driving device, a developing solution is dropped on the photoresist 51 while the glass substrate 50 is being rotated to perform a developing process. As a result, an uneven pattern corresponding to the trapezoidal wave wobble of the wobbling groove 5 is formed on the glass substrate 50.

Next, a conductive film made of, for example, Ni or the like is formed on the glass substrate 50 on which the concavo-convex pattern is formed by an electroless plating method, and then the glass substrate 50 on which the conductive film is formed is removed. Attached to an electroforming apparatus, a plating layer made of Ni or the like is
It is formed so as to have a thickness of about 00 ± 5 μm. Thereafter, the plating layer is peeled off, and the peeled plating is washed with acetone or the like to complete a master for manufacturing an optical recording medium having a concavo-convex pattern, a so-called stamper.

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,
This optical recording medium manufacturing master is an optical recording medium manufacturing master used when manufacturing an optical disk having wobbling grooves 5 formed along recording tracks,
An uneven pattern corresponding to the trapezoidal wave wobble of the wobbling groove 5 or a substantially rectangular wobbling (hereinafter, referred to as wobbling).
It is called a rectangular wobble. ) Wobbling groove 5
Is formed in a spiral shape corresponding to.

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, for example, a 2% by weight solution of a cyanine dye in tetrafluoropropanol (TFP) was dropped on the disk substrate 1 prepared as described above, and the disk substrate 1 was cooled at a speed of 4000 rpm for 20 minutes. Spin for 2 seconds and shake 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.

Next, as a reflection film 3 on the recording layer 2,
For example, after a silver thin film having a thickness of 100 nm is formed by sputtering, for example, an ultraviolet curable resin having a thickness of 10 μm is applied by spin coating, and the ultraviolet curable resin is irradiated with ultraviolet light to be cured, whereby the protective layer 4 is formed. To form Thereby, a CD-R to which the present invention is applied is completed.

<Evaluation of Double-Density CD-R> Next, a double-density CD-R was actually manufactured by the above-described manufacturing method and evaluated. Hereinafter, the evaluation results 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 prepared. 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.

As the double-density CD-R for the evaluation, the fundamental wave (sine wave wobble), the fundamental wave + third harmonic superimposed wobble (trapezoidal wobble), the fundamental wave + third harmonic, A double-density CD-R including four types of wobbling grooves 5 of a fifth-order harmonic superimposed wobble (trapezoidal wave wobble) and a rectangular wobble is manufactured, and the wobble amplitude of the wobbling groove 5 is changed for each region. did.

The double-density CD-R for each evaluation produced as described above was rotated at a linear velocity of 0.88 m / sec using an optical recording / reproducing apparatus 30 as shown in FIG. , Tracking on the wobbling groove 5,
An EFM signal was recorded on a dye recording film in a wobbling groove 5 at a predetermined position while demodulating an FM-modulated wobble signal having a frequency of 22.05 kHz and obtaining absolute time information. Using this optical recording / reproducing apparatus 30, the EFM signal recorded on the double density CD-R for each evaluation was reproduced.

Here, the optical recording / reproducing apparatus 30 shown in FIG.
Is a 0.88 m / sec double density CD-R for each evaluation.
A spindle motor 31 for rotating at a linear speed of The recording / reproducing apparatus 30 has a wavelength λ of about 7
A semiconductor laser 32 that emits 80 nm laser light;
The optical system includes an objective lens 33 having a numerical aperture NA of 0.55, a quarter-wave plate 34, a beam splitter 35, a collimator lens 36, and a two-divided photodetector 37.

The two-divided photodetector 37 is composed of light receiving elements 37A and 37B divided corresponding to the radial direction of each double density CD-R which is 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 this optical recording / reproducing apparatus 30, when the output signal of the amplifier 38A is Sa and the output of the amplifier 38B is Sb, the adding circuit 39 (Sa + S
The HF signal (EFM signal) of b) 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 optical recording / reproducing apparatus 30, a push-pull signal is extracted from the output terminal 42. This push-pull signal includes a tracking error signal 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 from the waveform shaping circuit 44 is FM
The data is supplied to the decoder 45. Thereby, the output terminal 46
From the absolute time information.

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.

Using the recording / reproducing apparatus 30 as described above,
Perform recording / reproducing on double density CD-R for each evaluation,
For each wobble amplitude amount, the wobble C /
N and the jitter of the signal (EFM signal) recorded in the wobbling groove 5 were measured. Hereinafter, the measurement results are shown in Table 1. In Table 1, the CD-ROM standardized by the Orange Book
The wobble C / N of R before recording is 35 dB or more;
The wobble C / N after recording is 26 dB or more, and the jitter is 35 ns or less.

[0072]

[Table 1]

As shown in Table 1, a double-density CD- consisting of a fundamental wave + third harmonic superimposed wobbles (trapezoidal wobbles)
In R, the wobble C / N before and after recording with respect to the wobble amplitude amount is better than the existing double-density CD-R consisting of a fundamental wave (sine wave wobble), and sufficiently satisfies the standard. I understand. In addition, this fundamental wave +3
In a double-density CD-R composed of the second harmonic superimposed wobble,
It can be seen that the jitter with respect to the wobble amplitude amount is better than the existing double-density CD-R consisting of a fundamental wave (sine wave wobble), and sufficiently satisfies the standard.

As described above, in the double-density CD-R in which the trapezoidal wave is wobbled by the fundamental wave + the third harmonic superimposed wobble, the wobble amplitude of the wobbling groove 5 is smaller than that of the wobble C / W before and after the recording. N is good, and the jitter of the signal recorded in the wobbling groove 5 is good.

Further, as shown in Table 1, in a double-density CD-R comprising a fundamental wave + third harmonic and a fifth harmonic superimposed wobble (trapezoidal wobble), before and after recording with respect to the wobble amplitude amount. It can be seen that the wobble C / N is better than the existing double-density CD-R consisting of a fundamental wave (sine wave wobble), and sufficiently satisfies the standard.
In addition, 2 which is composed of the fundamental wave and the third harmonic superimposed wobble.
In the double-density CD-R, the jitter with respect to the wobble amplitude amount is better than that of the existing double-density CD-R consisting of a fundamental wave (sinusoidal wobble), and the standard is sufficiently satisfied.

As described above, in the double-density CD-R in which the trapezoidal wave wobble is formed by the fundamental wave + the third harmonic and the fifth harmonic superimposed wobble, the wobble amplitude of the wobbling groove 5 is not recorded before and after the recording. The later wobble C / N is good, and the jitter of the signal recorded in the wobbling groove 5 is good.

Further, as shown in Table 1, in a double-density CD-R comprising rectangular wobbles, the wobble C / N before and after the recording with respect to the wobble amplitude amount is equal to the existing wobble comprising the fundamental wave (sine wave wobble). It is better than the double density CD-R of the above, and it can be seen that the standard is sufficiently satisfied.
In addition, in the double-density CD-R including the rectangular wobbles, it can be seen that the jitter with respect to the wobble amplitude amount is better than the standard.

As described above, in the double-density CD-R having a rectangular wobble, the wobble C / N before and after the recording is better than the wobble amplitude of the wobbling groove 5. Further, the jitter of the signal recorded in the wobbling groove 5 is good.

As described above, in the double-density CD-R to which the present invention is applied, the wobbling groove 5 is wobbled in a substantially trapezoidal or substantially rectangular shape along the recording track. The wobble C / N is good for the amplitude amount, and the jitter of the signal (EFM signal) recorded in the wobbling groove 5 is good.

Therefore, the double density C to which the present invention is applied
In the DR, it is possible to obtain a sufficient wobble C / N without increasing the wobble amplitude, so that the jitter of the signal recorded in the wobbling groove 5 due to the increase in the wobble amplitude is reduced. Thus, the recording density can be greatly improved.

Here, the trapezoidal wave wobble is not limited to the fundamental wave + the third harmonic superimposed wobble, or the fundamental wave + the third harmonic and the fifth harmonic superimposed wobble. For example,
Fundamental waves such as wobble superimposed with fundamental wave + third harmonic, fifth harmonic and seventh harmonic, wobble superimposed with fundamental wave + third harmonic, fifth harmonic, seventh harmonic and ninth harmonic By superimposing an appropriate amount of 2n + 1 harmonics (n is a natural number), which is a harmonic component, sequentially on (sine wave wobble), any trapezoidal wobble may be used. In this case, the same effect can be obtained. It is possible to get.

Here, in an optical recording / reproducing apparatus for recording / reproducing a signal to / from a double-density CD-R, a higher density is achieved by improving the resolution of an optical pickup.

For example, while the NA of the optical pickup for a single density CD-R is 0.45, the NA of the optical pickup for a double density CD-R is 0.55.
To improve the resolution of the optical pickup.

However, in this case, the resolution of the optical pickup is improved by (0.55 / 0.45) ² = 1.
Only 494 times higher density can be expected.

As described above, in the conventional optical recording / reproducing apparatus,
Double density CD only by improving the resolution of optical pickup
It is difficult to achieve a higher recording density for -R.

On the other hand, when the present invention is applied, the reproduction characteristic of the wobble signal detected from the wobbling groove and the signal (EFM signal) recorded in the wobbling groove are realized while increasing the recording density. ) Can be achieved at a high level.

In the current single-density CD-R,
The track pitch is about 1.60 μm, the linear velocity is about 1.20 to 1.40 m / sec, and the wobble amplitude width of the wobble groove is about ± 30 nm.

The above description is based on the assumption that the present invention relates to a double density CD-R.
Has been described, but the present invention is not limited to the above example, and a mini disc (MD: Mini D
It is possible to rewrite signals, such as a magneto-optical disk that records and reproduces signals using the magneto-optical effect, such as isc), and a phase-change optical disk that records and reproduces signals using the phase change of the recording film. It is applicable to all types of optical disks.

That is, in the case of an optical recording medium in which a wobbling groove is formed along a recording track, the wobbling groove is wobbled in a substantially trapezoidal shape or a substantially rectangular shape so that the wobbling amplitude of the wobbling groove can be reduced. Since the wobble C / N is good, a sufficient wobble C / N can be obtained without increasing the wobble amplitude. By applying the present invention, it is possible to suppress the deterioration of the jitter of the signal recorded on the recording track due to the increase in the wobble amplitude, and the jitter of the EFM signal recorded on the recording track is improved. .

Therefore, while realizing high recording density, the reproduction characteristics of the signal recorded on the recording track and
It is possible to provide a high-quality optical recording medium in which reproduction characteristics of a wobble signal detected from a wobbling groove are compatible with a high dimension.

Incidentally, as such an optical recording medium, a signal (EFM signal) is applied to a predetermined recording track while detecting a wobble signal from a wobbling groove, such as a CD-R, MD, or CD-RW. Optical discs on which recording and reproduction are performed. Also, the present invention relates to DVD + RW, DVD-R, DVD-RW
As described above, the present invention can be applied to optical disks having different HF modulation / demodulation signals and wobble modulation / demodulation signals.

[0092]

As described above in detail, according to the present invention, since the wobbling groove is wobbled in a substantially trapezoidal or substantially rectangular shape along the recording track, the wobble amplitude of the wobbling groove is reduced. On the other hand, the wobble C / N is good, and the jitter of the signal recorded on the recording track is good.

Therefore, according to the present invention, it is possible to obtain a sufficient wobble C / N without increasing the wobble amplitude amount, and therefore, it is possible to suppress the deterioration of jitter due to the increase in the wobble amplitude amount. This makes it possible to greatly improve the recording density.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view showing a main part of a double density CD-R to which the present invention is applied.

FIG. 2 is an enlarged plan view showing a part of a recording area of the double-density CD-R, showing a state in which a wobble groove is wobbled in a substantially trapezoidal shape.

FIG. 3 is an enlarged plan view showing a part of a recording area of the double-density CD-R, showing a state in which a wobble groove is wobbled in a substantially rectangular shape.

FIG. 4 is a schematic diagram showing an example of a laser cutting device used when producing an optical recording medium producing master used when producing the optical disc.

FIG. 5 is a schematic diagram showing an example of an optical recording / reproducing apparatus for recording / reproducing a signal to / from the optical disc.

FIG. 6 is a schematic diagram showing an example of an optical recording / reproducing apparatus to which the present invention has been applied.

[Explanation of symbols]

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

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Takemoto 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Manabu Sato 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 5D029 WA02 WD08 WD19 5D090 BB01 BB03 BB04 CC01 CC05 CC14 DD03 DD05 EE01 EE12 FF08 FF11 GG03 GG09 5D121 AA09 BA10 BB21

Claims (19)

[Claims] 1. An optical recording medium in which a wobbling groove is formed along a recording track, and a signal is recorded and / or reproduced on a predetermined recording track while detecting a wobble signal from the wobbling groove. An optical recording medium, wherein the wobbling groove is wobbled in a substantially trapezoidal shape. 2. The wobbling groove is wobbled in a substantially trapezoidal shape by sequentially superimposing 2n + 1 order harmonics (n is a natural number) on a fundamental wave having a sine waveform. Optical recording medium. 3. The optical recording medium according to claim 2, wherein the wobbling groove is wobbled in a substantially trapezoidal shape by superimposing a third harmonic on a fundamental wave having a sine waveform. 4. The wobbling groove according to claim 2, wherein the wobbling groove is wobbled in a substantially trapezoidal shape by superimposing a third harmonic and a fifth harmonic on a fundamental wave having a sine waveform. Optical recording medium. 5. The light according to claim 1, further comprising a recording layer made of an organic dye-based recording material, wherein a signal recorded on the recording track is recorded as a change in reflectance of the recording layer. recoding media. 6. An optical recording medium in which a wobbling groove is formed along a recording track, and a signal is recorded and / or reproduced on a predetermined recording track while detecting a wobble signal from the wobbling groove. An optical recording medium, wherein the wobbling groove is wobbled in a substantially rectangular shape. 7. The light according to claim 6, further comprising a recording layer made of an organic dye-based recording material, wherein a signal recorded on the recording track is recorded as a change in reflectance of the recording layer. recoding media. 8. An optical recording medium in which a wobbling groove is formed along a recording track and a signal is recorded and / or reproduced on a predetermined recording track while detecting a wobble signal from the wobbling groove. An optical recording medium for use in manufacturing an optical recording medium, wherein an uneven pattern corresponding to a wobbling groove formed on the optical recording medium is formed while being wobbled in a substantially trapezoidal shape. Master for media production. 9. The irregular pattern is wobbled in a substantially trapezoidal shape by sequentially superimposing a 2n + 1-order harmonic (n is a natural number) on a fundamental wave having a sine waveform. Master for the production of optical recording media. 10. The optical recording medium according to claim 9, wherein the uneven pattern is wobbled in a substantially trapezoidal shape by superimposing a third harmonic on a fundamental wave having a sinusoidal waveform. Master. 11. The rugged pattern is wobbled in a substantially trapezoidal shape by superimposing a third harmonic and a fifth harmonic on a sinusoidal fundamental wave. Master for optical recording media production. 12. A wobbling groove is formed along a recording track, and an optical recording medium for recording and / or reproducing a signal on a predetermined recording track while manufacturing a wobble signal from the wobbling groove is manufactured. An optical recording medium for use in producing an optical recording medium, wherein an uneven pattern corresponding to a wobbling groove formed on the optical recording medium is formed while being wobbled in a substantially rectangular shape. Master for media production. 13. An optical recording medium having a wobbling groove formed along a recording track, wherein a signal is recorded and / or recorded on a predetermined recording track while detecting a wobble signal from the wobbling groove of the optical recording medium.
An optical recording / reproducing apparatus for performing reproduction, wherein the wobbling groove of the optical recording medium is wobbled in a substantially trapezoidal shape. 14. In the optical recording medium, the wobbling groove is wobbled in a substantially trapezoidal shape by sequentially superimposing a 2n + 1-order harmonic (n is a natural number) on a fundamental wave having a sine waveform. The optical recording / reproducing apparatus according to claim 13, wherein 15. The optical recording medium according to claim 14, wherein the wobbling groove is wobbled in a substantially trapezoidal shape by superimposing a third harmonic on a sinusoidal fundamental wave. Optical recording and reproducing device. 16. The optical recording medium, wherein the wobbling groove is wobbled in a substantially trapezoidal shape by superimposing a third harmonic and a fifth harmonic on a sine waveform fundamental wave. The optical recording / reproducing apparatus according to claim 14, wherein 17. The optical recording medium has a recording layer made of an organic dye-based recording material, and a signal recorded on the recording track is recorded as a change in the reflectance of the recording layer. An optical recording / reproducing apparatus according to claim 13. 18. An optical recording medium having a wobbling groove formed along a recording track, and recording and / or recording of a signal on a predetermined recording track while detecting a wobble signal from the wobbling groove of the optical recording medium.
An optical recording / reproducing apparatus for performing reproduction, wherein the optical recording medium is formed by wobbling the wobbling groove in a substantially rectangular shape. 19. The optical recording medium has a recording layer made of an organic dye-based recording material, and a signal recorded on the recording track is recorded as a change in reflectance of the recording layer. The optical recording / reproducing apparatus according to claim 18.