JP2003157572A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which has small in-plane variation of tracking servo signals, stable servo characteristics, improved jitters in a ROM part, and small wobble jitters and which can securely reproduce ATIP (absolute time in pre-groove) information while being well matched with various drives. SOLUTION: The optical recording medium has a ROM region where pits are preliminarily formed and a RAM region having recordable groove where pits or marks for reproducing data are formed by irradiation with laser light. The ROM region is composed of pit lines wobbled in the radial direction and an inter-pit groove is formed along the lines of the wobbled pits. The width of the inter-pit groove is narrower than that of the groove in the RAM region. The ratio of the width of the inter-pit groove to the track pitch is from 0.2 to 0.4.

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 for recording by laser light and reproducing recorded data by reflected light, and a ROM area in which data is recorded by mastering in advance and a recordable area for additional recording. Alternatively, the present invention relates to a hybrid optical recording medium having a recordable / erasable rewritable area. In general optical discs, binary digital data is formed on a spiral or concentric circular track with uneven pits (ROM disc) by embossing or the like, or pit formation on an inorganic / organic recording film (write-once disc). It is recorded due to the difference in crystal state (phase change disk). When these recorded data are reproduced, a laser beam is irradiated onto the track and the intensity difference of the reflected light is detected to obtain a reproduction signal. ROM discs, such as CD, CD-ROM, DVD-ROM,
By transferring the uneven pits formed on the master to the molding plate, a large amount can be inexpensively produced and used for distribution. The concave and convex pits on the master are formed by forming a resist on a glass substrate or the like and irradiating a laser beam on the resist to form a latent image.
It is formed by development.

Recordable discs such as the write-once disc and the phase change disc are CD-R, CD-RW, and DVD-
Like R, DVD-RW, DVD + R, DVD + RW, etc., guide grooves for tracking are formed in the same manner as a ROM disk from a master, and the guide grooves are transferred to a molding plate, and then inorganic or organic. It is created by providing a recording film or the like, and information is recorded by a recording / reproducing device (CD-R drive or the like). The ROM disc and the recordable disc such as the write-once disc and the phase change disc are a CD-ROM.
And CD-R (CD-RW), DVD-ROM and DVD-
Like the relationship of R (DVD-RW, DVD + R, DVD + RW), it is required that the recordable disc recorded by the recording drive can be reproduced by the same reproducing device as the ROM disc. This is achieved by making the recordable disc and the ROM disc recorded in the same format, and the signals to be reproduced are substantially the same in the recordable disc and the ROM disc.

In the above CD-R and the like, the address information is wo
In the guide groove recorded as bble,
This is realized by forming recording pits in the recording drive, which have the same reproduction signal as ROM pits. In addition, R having a recordable area in a part of the ROM disc
An optical disk of a type having both an OM area and a recordable area is called a hybrid disk. Since this hybrid disc is injection-molded by the stamper, mass production is possible and cost reduction can be realized. Furthermore, since it has a recording area, RO that is mass-produced
It is possible to realize M data update, a recordable medium having control software for a recording drive, and the like. The present invention relates to this hybrid disc (hybrid CD-R disc,
Hybrid CD-RW disc, hybrid DVD
-R disc, hybrid DVD + R disc, hybrid DVD-RW disc, hybrid DVD +
Although it can be applied to RW discs and the like, it is particularly suitable for hybrid CD-R and hybrid CD-RW discs.

[0004]

2. Description of the Related Art A hybrid CD-R medium having a ROM portion consisting of pits by mastering on one surface and a recordable area of a groove portion is disclosed in Japanese Patent Publication No. 7-11402.
As can be seen in Japanese Patent Publication No. 8, the ROM part is initially a normal C
A reflective film was provided directly on the substrate pit with the same structure as D. However, since it is difficult to separately apply the dye at the boundary between the ROM part and the groove part, and it is more difficult to apply the dye to the inside of the ROM part, the dye is applied to both the pit part and the groove part, and The pit shape, the groove shape, and the dye coating state, in which the signal characteristics of the area and the groove are improved, have come to be limited. However, ROM
The push-pull signal of the part is a signal only from the intermittent pre-pits and is considerably smaller than the push-pull signal of the unrecorded signal obtained from the continuous groove.

Therefore, the modulation degree described in Orange Book, P
PA (Push-pull Amplitude = Push-pull amplitude / Rtop or push-pull amplitude / Ig)
Even if the characteristic items such as the above are satisfied, the signals of push-pull / Ig (unrecorded portion) and push-pull / Iga (ROM portion, write-once portion) normally used for the tracking servo of the recording apparatus are within the three-zone surface. Variation (hereinafter referred to as in-plane variation) may not be within ± 3 dB normally required by the recording apparatus, or within approximately ± 40% in terms of%. Especially, the reference servo gain is set in the inner peripheral ROM section. The drive has a problem that tracking is lost during recording or reproduction. Further, since the push-pull signal is small in the ROM section, the wobble signal is also small as a result, and the ATIP (Absolute Time In P
There is a problem that the re-groove information cannot be read. As a means for solving this problem, it is known to provide a groove (pit-to-pit groove) between pits along the ROM pit row.

In the invention described in JP-A-5-36087, a wobbled groove (pit groove) having the same shape as the RAM groove is provided along the ROM wobble pit row for the purpose of improving the ATIP signal. In this case, if the width of the groove in the RAM and the width of the groove in the pit are set to the same width, interference between the pit and the groove in the pit during exposure of the master becomes large, causing a sag before and after the pit and increasing the jitter in the ROM. There was a flaw. Further, there is a drawback that wobble jitter increases if the groove width between pits is made too small. Also,
Even in the invention described in JP-A-9-138977, the AT
Although wobbled pit grooves are provided for the purpose of improving the IP signal, the pits are not wobbled in order to suppress ROM section jitter. Further, in the case of the present invention, at the time of exposing the master, two optical beams for the exposure of the pits and the groove between the pits are always required, so that the optical system becomes complicated, and the relative adjustment of the two beams is difficult, so The upper difficulty was high. Further, there is a drawback that wobble jitter becomes large unless the pits are wobbled.

[0007]

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned drawbacks of the prior art, reduces the in-plane fluctuation of the tracking servo signal, stabilizes the servo characteristics, reliably improves the jitter in the ROM portion, and reduces the wobble jitter. The present invention aims to provide an optical recording medium that can be reproduced, ATIP information can be reliably reproduced, and good matching with a drive.

[0008]

[Means for Solving the Problems] The above problems are solved in the following 1) to
This is solved by the invention 3) (hereinafter referred to as the present inventions 1 to 3). 1) ROM area where pits are formed in advance on the substrate,
An optical recording medium having a RAM area having a recordable groove in which data reproduction pits or marks are formed by laser light irradiation, wherein the ROM area is composed of pit rows wobbled in a radial direction. Grooves are formed between the wobbling pits along the pit row, and the width of the inter-pit groove is R.
An optical recording medium characterized in that it is narrower than the groove width of the AM region and has a ratio to the track pitch in the range of 0.2 to 0.4. 2) The optical recording medium is a write-once CD (CD-R) 1)
The optical recording medium described. 3) The optical recording medium according to 1), wherein the optical recording medium is a rewritable CD (CD-RW).

The present invention will be described in detail below. By providing the groove between pits, the push-pull signal generated from the groove between pits is added to the push-pull signal generated from the pit, and the push-pull amplitude of the ROM part is PP, the push-pull amplitude of the unrecorded part of the RAM part is PPb, When the write-once push-pull amplitude of the RAM section is PPa, push-pull amplitude / Iga (PP / Ig of the ROM section, which is generally used for tracking servo signals.
a) is the push-pull amplitude / Ig of the unrecorded area in the RAM area.
The difference between (PPb / Ig) and the write-once portion push-pull amplitude / Iga (PPa / Iga) of the RAM portion becomes small, and the servo characteristic is improved. The shape of the connection between the pits and the groove between the pits is more or less affected by the overlap of the beam light of the pits and the groove between the pits during exposure of the master, as compared with the case of only the pits. In order to make the ROM part push-pull signal as large as possible, it is necessary to make the beam irradiation pulse interval of the pit and the groove between the pits small or continuous, but in that case, since the overlap of the beam light becomes large, The sag increases and the jitter increases. As the groove width between pits is larger, the beam intensity at the time of groove exposure between pits needs to be larger, so that the overlap of the beam light becomes larger and the jitter becomes larger.

From the viewpoint of reducing the difference from the signal characteristics of the RAM section, the reflectance peak value (Rto) of the recording signal.
In p), it is better that the groove width between pits and the groove width of the RAM section are the same (when the depths are the same).
Considering the M-section jitter, the groove width between pits should be small. On the other hand, it was found that the wobble signal is an important signal in terms of disc characteristics, but if the groove width between pits is small, the wobble signal jitter increases and the matching property with the drive deteriorates. Therefore, the groove width between pits has an upper limit and a lower limit, and the present inventors have found that the ratio to the track pitch is 0.2 to 0.4. In particular, the range of 0.25 to 0.35 is preferable in terms of matching with the actual drive, and more preferably 0.
It is in the range of 25 to 0.30.

The width of the substrate groove of the RAM part is the same as that of a normal CD.
-R is 0.4 to 0.7 μm, and the groove width between pits is 0.30 to 0.65 μm, preferably 0.40 to
It is 0.50 μm. In the case of a CD-R, the substrate depth of the groove in the RAM section and the groove between the pits is the normal C
Like DR, it is 1200 to 2200Å, and both groove depths are preferably the same depth from the viewpoint of ease of master production in the master production process described later. In the CD-R, the substrate depth of the ROM pit is 250 in order to obtain the modulation degree of the Orange Book standard and the push-pull signal.
0-3500Å is suitable.

The ROM section pits, the inter-pit grooves,
As a method for producing a master for realizing each substrate shape of the RAM groove, the exposure intensity is changed with respect to one layer of photoresist coated on the glass plate as in the case of a general CD-R master. There is also a method of exposing the groove between the deep ROM pits and the shallow pits / RAM groove,
In order to suppress the variation in the depth of the pit-groove / RAM groove, it is preferable to use a two-layer resist method in which an intermediate layer is sandwiched on a glass master. Irradiation with a strong laser power (4.0 mW to 5.0 mW) at the time of pit exposure in the ROM section, and at the time of groove exposure between the pits and the RAM section groove exposure,
Insufficient laser power (2.
Irradiate weakly at 0 mW to 3.5 mW).

As the exposure method, the intensity of the exposure beam with which the master is irradiated is determined by the pits in the ROM section, the grooves between the pits and the RA.
There are a one-beam exposure method that switches according to the M section groove, and an exposure method that prepares multiple beams and switches according to the ROM section pit / pit groove / RAM section groove. In order to prevent an increase in jitter due to positional deviation of the beam, it is desirable to switch the intensity of one beam to perform exposure. RA
In the M section, one beam is divided into two spots slightly shifted in the radial direction on the resist irradiation surface to be exposed, thereby exposing the RAM section groove wider than the inter-pit groove. After the exposure, each shape is obtained through the steps of development → intermediate layer etching → second development step. The master thus obtained is subjected to electroconductivity treatment, and then electroformed to form a stamper, and the stamper is used to form a substrate for a hybrid optical recording medium by molding. As the substrate material, polycarbonate resin,
Acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polystyrene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin and the like,
A polycarbonate resin and an acrylic resin, which are excellent in terms of moldability, optical characteristics and cost, are preferable.

To prepare a write-once hybrid type optical information recording medium, a light absorbing layer is first provided on the substrate.
Generally, a dye material is applied to a film thickness of 500 to 3 by a spinner method.
Apply 000Å. Materials include cyanine-based, phthalocyanine-based, naphthalocyanine-based, anthraquinone-based,
Azo type, triphenylmethane type, pyrylium or thiapyrylium salt type, squarylium type, croconium type,
It is preferable to select one or more selected from metal complex dyes. A reflective layer is provided on the recording layer in direct contact with it. As a material for the reflective layer, it is preferable to use a high-reflectance metal or alloy such as Ag, Au, or Cu. The reflective layer preferably has a thickness of 500 to 2000 liters and is provided by vapor deposition, sputtering or the like. A protective film is preferably provided on the reflective layer. The protective film is usually 1
It is formed by a spinner method or the like to have a thickness of about 10 μm. Further, an ultraviolet curable resin or the like may be provided on the protective film as an upper protective film by screen printing or the like in an amount of 5 to 100 μm.

The rewritable hybrid optical information recording medium has a structure in which a first dielectric layer (first protective layer), a recording layer, a second dielectric layer (second protective layer), and It is preferable that the reflection (heat dissipation) layers are laminated in that order, and a protective film is further provided on the reflection (heat dissipation) layer for protection. The substrate and the protective film material used are the same as those of the write-once hybrid optical recording medium. As the recording layer, Ag, I
A material containing a quaternary phase-change recording material containing n, Sb, and Te as a main component has extremely good recording (amorphization) sensitivity / speed, erasing (crystallization) sensitivity / speed, and erasing ratio. Therefore, it is preferable. Other elements and impurities can be added for further improvement in performance and reliability.
The elements to be added include B, N, C, P, Si and G.
e, O, S, Se, Al, Ti, Zr, V, Mn, F
e, Co, Ni, Cr, Cu, Zn, Ga, Sn, P
Preferred examples include d, Pt, Au and the like. The thickness of the recording layer is 17 to 100 nm, preferably 17 to 30 nm
And

Materials for the first and second dielectric layers (protective layers) include SiOx, ZnO, SnO ₂ , Al ₂ O ₃ , and
TiO ₂ , In ₂ O ₃ , MgO, ZrO ₂ , Ta ₂ O ₅
Metal oxides such as; Si ₃ N ₄ , AlN, TiN, BN,
ZrN and other nitrides; ZnS, TaS _{4 and} other sulfides; Si
Carbides such as C, TaC, B ₄ C, WC, TiC, and ZrC can be mentioned. These materials can be used alone as a protective layer, or can be used as a mixture, and the film thickness of the first dielectric layer is in the range of 50 to 250 nm.
75-200 nm is preferable. The film thickness of the second derivative layer is set in the range of 10 to 100 nm, preferably 15 to 50 nm. As the reflection (heat dissipation) layer, Al, Au, Cu, A
g, Cr, Sn, Zn, In, Pd, Zr, Fe, C
A simple substance, an alloy, or a mixture of materials such as o, Ni, Si, Ge, Sb, Ta, W, Ti, and Pb can be used. If necessary, a plurality of different metals, alloys or mixtures may be laminated. It is important that this layer efficiently dissipate heat, and the film thickness is 30 to 250 nm.
And The thickness is preferably 50 to 200 nm.

[0017]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 TOC (Table of Conte) was formed on the surface of a polycarbonate disk having a diameter of 120 mm and a thickness of 1.2 mm.
nts) and the inside of the radius of 35 mm, depth 2850
Å, pits with a width of 0.6 μm, track pitch of 1.6 μm, and depths connecting the pits with a depth of 1500 Å, width of 0.4 μm
(Ratio to track pitch = 0.25), wobble amplitude 35
A groove between pits of nm was provided. Further, on the outside of it, depth 1500Å, width 0.7μm, track pitch 1.6μ
A guide groove of m is provided. On this disk, a light absorption layer made of a phthalocyanine dye and having an average thickness of 900 Å (the pit portion, the space portion, the groove portion, and the land portion have different thicknesses, the average value thereof is shown) is used. After spin coating using a mixed solvent containing cyclohexane as a main component, heat treatment was performed at 100 ° C. for 30 minutes. Then, a reflective layer of Ag having a thickness of about 1400 Å was provided on it by a sputtering method. Further, an ultraviolet curable resin was applied thereon by a spinner and cured by ultraviolet rays to form a protective layer having a thickness of about 5 μm. Finally, a UV curable ink is applied thereon by a screen printing method and cured by UV to a thickness of about 10
An upper protective layer having a thickness of μm was provided to obtain a CD-R optical recording medium.
When the above medium was reproduced by a recording / reproducing apparatus having a pickup with a laser beam wavelength of 780Å, the ROM section 3T jitter was land = 28 ns (nanosecond), pit = 26 n.
It was s. Ratio (PP / Iga: PPb / Ig: PPa / I) of each servo gain of the pit part of the ROM part, the unrecorded part of the RAM part, and the write-once part of the RAM part (after optimum power recording).
Ga) was 1: 0.78: 0.98, which sufficiently satisfied the in-plane variation of ± 40% required from the servo characteristics.
In addition, Rtop of the ROM section = 70.4%, PPA = 0.
087, 11T modulation degree = 0.65, 3T modulation degree = 0.4
4, which satisfied the Orange Book standard. Further, the wobble jitter was 11.6 μs (microsecond), and the matching with the drive of each company was good.

Comparative Example 1 On the surface of a polycarbonate disc having a diameter of 120 mm and a thickness of 1.2 mm, the TOC portion and the inner side of a radius of 35 mm,
Depth 2890Å, width 0.6μm, track pitch 1.6
μm pits and the depth of 1550Å connecting the pits,
A pit groove having a width of 0.25 μm (ratio to track pitch = 0.16) and a wobble amplitude of 35 nm was provided. Further, a guide groove having a depth of 1550Å, a width of 0.7 μm and a track pitch of 1.6 μm was provided on the outer side thereof. Subsequent manufacturing steps were the same as in Example 1 to obtain a CD-R optical recording medium.
When the above medium was reproduced by a recording / reproducing apparatus having a pickup having a laser beam wavelength of 780Å, the ROM section 3T jitter was land = 25 ns, pit = 24 ns. Pit part of ROM part, unrecorded part of RAM part, RAM
The ratio (PP / Iga: PPb / Ig: PPa / Iga) of each servo gain of the additional recording part (after optimum power recording) is
The ratio was 1: 0.83: 1.04, which satisfied the in-plane variation of ± 40% required from the servo characteristics. Also, RO
Rtop of M part = 71.7%, PPA = 0.081, 1
1T modulation degree = 0.68, 3T modulation degree = 0.46,
Satisfies the Orange Book standard. However, the wobble jitter was 20.4 μs, and the matching with the drive of each company was poor.

Example 2 On the surface of a polycarbonate disc having a diameter of 120 mm and a thickness of 1.2 mm, up to the inside of the TOC portion and a radius of 35 mm,
Depth 3100Å, width 0.6μm, track pitch 1.6
μm pits and a depth of 1650Å connecting the pits,
A groove between pits having a width of 0.35 μm (ratio to track pitch = 0.22) and a wobble amplitude of 35 nm was provided. Further, a guide groove having a depth of 1650Å, a width of 0.7 μm and a track pitch of 1.6 μm was provided on the outer side thereof. Subsequent manufacturing steps were the same as in Example 1 to obtain a CD-R optical recording medium. When the above medium was reproduced by a recording / reproducing apparatus having a pickup having a laser beam wavelength of 780Å, the ROM section 3T
The jitter was land = 27 ns and pit = 25 ns. Pit part of ROM part, unrecorded part of RAM part, RA
Ratio of servo gains of the write-once portion of M portion (after optimum power recording) (PP / Iga: PPb / Ig: PPa / Iga)
Is 1: 0.81: 1.01, which satisfies the in-plane variation of ± 40% required from the servo characteristics. Also,
Rtop of ROM section = 71.2%, PPA = 0.08
3,11T modulation degree = 0.72, 3T modulation degree = 0.47, which satisfied the Orange Book standard. Further, the wobble jitter was 14.5 μs, and the matching with the drive of each company was good.

Comparative Example 2 On the surface of a polycarbonate disk having a diameter of 120 mm and a thickness of 1.2 mm, the TOC portion and the inner side of a radius of 35 mm,
Depth 2910Å, width 0.7μm, track pitch 1.6
μm pits and a depth of 1500 Å connecting the pits,
A groove having a width of 0.7 μm (ratio to track pitch = 0.44) and a wobble amplitude of 35 nm was provided between the pits. Furthermore,
A guide groove having a depth of 1500 Å, a width of 0.7 μm and a track pitch of 1.6 μm was provided on the outer side thereof. Subsequent manufacturing steps were the same as in Example 1 to obtain a CD-R optical recording medium. When the above medium was reproduced by a recording / reproducing apparatus having a pickup with a laser light wavelength of 780Å, the ratio of each servo gain of the pit part of the ROM part, the unrecorded part of the RAM part, and the write-once part of the RAM part (after optimum power recording) ( PP / Iga: PP
b / Ig: PPa / Iga) is 1: 0.75: 0.9.
4, which is the in-plane variation required from the servo characteristics ± 40%
Satisfied within. Also, Rtop of the ROM section = 6
9.8%, PPA = 0.090, 11T modulation = 0.6
The degree of 3T modulation was 0.42, which satisfied the Orange Book standard. The wobble jitter was good at 9.2 μs. However, the ROM section 3T jitter was land = 34 ns, pit = 33 ns, and was almost 35 ns at the Orange Book standard.

Example 3 On the surface of a polycarbonate disc having a diameter of 120 mm and a thickness of 1.2 mm, up to the inside of the TOC portion and a radius of 35 mm,
Depth 3100Å, width 0.6μm, track pitch 1.6
A pit having a size of 1 μm and a depth of 1650 Å connecting the pits, a width of 0.6 μm (ratio to track pitch = 0.38), and a groove between pits having a wobble amplitude of 35 nm were provided. Further, a guide groove having a depth of 1650Å, a width of 0.7 μm and a track pitch of 1.6 μm was provided on the outer side thereof. Subsequent manufacturing steps were the same as in Example 1 to obtain a CD-R optical recording medium. When the above medium was reproduced by a recording / reproducing apparatus having a pickup having a laser beam wavelength of 780 Å, the ROM section 3T jitter was land = 30 ns and pit = 28 ns. R
Ratio of servo gains of the pit part of the OM part, the unrecorded part of the RAM part, and the write-once part of the RAM part (after optimum power recording) (PP
/ Iga: PPb / Ig: PPa / Iga) is 1: 0.
741: 0.94, which satisfies the in-plane variation ± 40% required from the servo characteristics. Further, Rtop of the ROM part was 70.1%, PPA was 0.089, 11T modulation was 0.64, and 3T modulation was 0.43, which satisfied the Orange Book standard. Wobble jitter is 1
It was 0.4 μs, and the matching with the drive of each company was good.

Example 4 On the surface of a polycarbonate disc having a diameter of 120 mm and a thickness of 1.2 mm, up to the inside of the TOC portion and a radius of 35 mm,
Depth 1000Å, width 0.65 μm, track pitch 1.
6 μm pits and a depth of 400 Å connecting the pits,
A groove between pits having a width of 0.4 μm (ratio to track pitch = 0.25) and a wobble amplitude of 35 nm was provided. Furthermore,
A guide groove having a depth of 400 Å, a width of 0.5 μm and a track pitch of 1.6 μm was provided on the outer side thereof. For this disc, the first
ZnS-SiO _{2 with} a film thickness of 700 Å as the dielectric layer, Ag-In-Sb-Te with a film thickness of 150 Å as the recording layer,
ZnS-SiO _{2 with a} film thickness of 200 Å as a dielectric layer and Ag with a film thickness of 1400 Å as _a reflection and heat dissipation layer are sequentially laminated by sputtering, and an ultraviolet curable resin is applied on top of this by a spinner and cured by ultraviolet rays to a thickness. A protective layer of about 5 μm was provided. Finally, an ultraviolet curable ink was applied thereon by a screen printing method and cured by ultraviolet rays to provide an upper protective layer having a thickness of about 10 μm, to obtain a CD-RW type optical recording medium. When the above medium was reproduced by a recording / reproducing apparatus having a pickup having a laser beam wavelength of 780Å, RO
M section 3T jitter, land = 24ns, pit = 21
It was ns. Ratio (PP / Iga: PPb / Ig: PPa / I) of each servo gain of the pit part of the ROM part, the unrecorded part of the RAM part, and the write-once part of the RAM part (after optimum power recording).
Ga) was 1: 0.77: 0.98, which sufficiently satisfied the in-plane variation of ± 40% required from the servo characteristics.
In addition, Rtop of the ROM section = 18.5%, PPA = 0.
088, 11T modulation degree = 0.68, 3T modulation degree = 0.5
It was 5, which satisfied the Orange Book standard. Further, the wobble jitter was 11.0 μs, and the matching with the drive of each company was good.

[0024]

According to the first aspect of the present invention, the in-plane variation of the tracking servo signal is small and the servo characteristic is stable, and
ROM part jitter can be improved more reliably. Also, wobble jitter can be reduced, and the matching with the drive becomes good. According to the present invention 2, a CD-R having the characteristics of the present invention 1 can be provided. According to the present invention 3, a CD-RW having the characteristics of the present invention 1 can be provided.

Claims (3)

[Claims] 1. A ROM having pits formed in advance on a substrate.
RAM having an area and a recordable groove in which a data reproduction pit or mark is formed by laser light irradiation
An optical recording medium having a region, wherein the ROM region comprises a row of wobbling pits in the radial direction, grooves are formed between the wobbling pits along the wobbling pit row, and the inter-pit groove is formed. Is narrower than the groove width of the RAM area and has a ratio to the track pitch in the range of 0.2 to 0.4. 2. The optical recording medium according to claim 1, which is a write-once type CD (CD-R). 3. An optical recording medium is a rewritable CD (CD-R).
The optical recording medium according to claim 1, which is W).