JP2002298444A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium suitable for high-speed recording by improving the stability of tracking in information recording and information reading by increasing reflectance in a pre-groove 6 and a margin of push-pull. SOLUTION: The groove width Wsub and the groove tilt angle Asub of the pre-groove 6 are restricted within the range of predetermined numerical values. The optical information recording medium includes a substrate 2 which has translucency and on which a pulley groove 6 is formed, a light absorbing layer 3 which is provided on the substrate 2 and absorbs recording light based on a laser beam, and a light-reflecting layer 4 which is provided on the light absorbing layer 3 and reflects the laser beam. 400 nm<=Wsub<=580 nm and 35<=Asub<=60 are satisfied, wherein Wsub is the groove width of the pre-groove 6 on the substrate 2 and Asub is the groove tilt angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium, and more particularly, to an optical information recording medium having at least a light absorbing layer and a light reflecting layer on a light transmitting substrate and capable of writing at high speed. It is.

[0002]

2. Description of the Related Art In a conventional optical information recording medium having a writable structure (so-called CD-R), various conditions must be satisfied in order to cope with high-speed recording.
For example, it is necessary to make the relationship between the reflectance Rg in the pre-groove forming the pit and the push-pull value for tracking appropriate.

In general, a so-called tracking method is known in which the irradiation position of a laser pickup is accurately positioned in a pit row on a CD so that recording and reproducing laser light can accurately track a CD track. A beam method and a push-pull method are known. In the push-pull method, the laser beam is accurately guided on a track by dividing the beam for tracking into two parts and comparing the reflected light amounts of respective sections irradiated by the respective beams. Such tracking can be employed not only in the optical information recording medium in the already recorded state but also in the optical information recording medium in the unrecorded state. The CD standard states that such a push-pull value is represented by (I1-I2) / I0. Where I0 is the intensity of the reflected light,
I1 and I2 are the left and right reflected light intensities, respectively.

In general, the reflectance Rg and the push-pull value are originally in a trade-off relationship with each other, and if the reflectance Rg is increased in order to efficiently record and read information, the push-pull value decreases. Therefore, there is a problem that it is difficult to perform stable tracking. Therefore, in order to respond to high-speed recording, the reflectance R
There is a demand for an optical information recording medium in which the push-pull value does not decrease even if g is increased.

Further, in order to synchronize the rotation of the optical information recording medium itself with the recording and reading of information, a wobble called so-called meandering or undulation is formed in the pregroove, but the jitter value of the wobble signal increases. Then, there is a problem that the spindle for rotating the disk becomes unstable and tracking stability during recording cannot be maintained. Therefore, it is also required to obtain tracking stability during recording by obtaining a wobble jitter value more appropriately even in high-speed recording.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an optical information recording medium suitable for high-speed recording.

Another object of the present invention is to provide an optical information recording medium having improved tracking stability during information recording and information reading.

Another object of the present invention is to provide an optical information recording medium capable of improving the stability of tracking during information recording and information reading by properly obtaining a jitter value.

[0009]

That is, the present invention focuses on limiting the groove width Wsub and the groove inclination angle Asub of the pre-groove to predetermined numerical ranges. A light-absorbing layer that is provided on the substrate and absorbs recording light by a laser beam, and a light-reflective layer that is provided on the light-absorbing layer and reflects the laser light; An optical information recording medium that records information by irradiating the recording layer with the recording light, wherein when the groove width of the pre-groove on the substrate is Wsub and the groove inclination angle is Asub, 400 nm ≦ Wsub ≦ 580 nm, and 3
An optical information recording medium, wherein 5 ° ≦ Asub ≦ 60 °.

When the groove depth of the pre-groove on the substrate is Dsub, 1.5 ≦ Wsub / Dsub ≦
3.7 is desirable.

In the present invention, the light absorbing layer may have a light absorbing substance composed of a benzoindodicarbocyanine dye having the following structural formula, and the average thickness of the light absorbing layer is 40 nm ≦ Dav. ≦ 80 nm, desirably 56n
An optical information recording medium, wherein m ≦ Dav ≦ 72 nm.

Embedded image Note that chlorine (C) is contained in the cyanine dye in the light absorbing layer.
1) It is desirable to design a material that does not contain bromine (Br) or iodine (I).

The light absorbing layer may contain an aminium salt compound having the following structural formula as a stabilizer.

Embedded image

From the layer boundary between the light absorbing layer and the light reflecting layer in the lands located on the left and right sides of the pregroove, the depth of the bottom of the layer boundary in the pregroove is Dabs; The real part of the complex refractive index of the substrate is ns
ub, the real part of the complex refractive index of the light absorption layer is nabs, the wavelength of the reproduction light is λ, the pregroove portion and the land portion of the reproduction light reflected by the light reflection layer are △ S = 2Dsub
When {nsub-nabs (1-Dabs / Dsub)} / λ, it is preferable that 0.15 ≦ △ S ≦ 0.55.

When the reference linear velocity at the time of recording on the optical information recording medium is Vm / s, the linear velocity is n · Vm / s.
(Where n is an integer of 12 or more). This reference linear velocity V is generally 1.2 m /
s (so-called 1 × speed).
Recording at double speed or higher is possible.

Next, the present invention will be described more specifically with reference to FIGS. FIG. 1 is a partially cutaway perspective view of an optical information recording medium 1 according to the present invention, FIG. 2 is a longitudinal sectional view of a main part of the optical information recording medium 1 before recording, and FIG. FIG. 3 is a longitudinal sectional view of a main part after recording of a medium 1. The optical information recording medium 1 includes a light-transmitting substrate 2, a light absorbing layer 3 formed on the substrate 2, a light reflecting layer 4 formed on the light absorbing layer 3, and a light reflecting layer 4. And a protective layer 5 formed thereon. In particular, as shown in FIGS. 2 and 3, a pregroove 6 is formed on the substrate 2 in a spiral shape.
To the left and right of the pre-groove 6, portions other than the pre-groove 6, that is, lands 7 are located.

Further, by forming undulations (wobbles 6W) in the pre-groove 6 along the circumferential direction of the optical information recording medium 1 shown in FIG. The rotation is synchronized with the information recording and reading, and the tracking action during recording is ensured.

The substrate 2 and the light absorbing layer 3 are in contact with each other by a first layer boundary 8. Light absorbing layer 3 and light reflecting layer 4
Is in contact with the second layer boundary 9. The light reflection layer 4 and the protective layer 5 are in contact with each other by a third layer boundary 10.

As shown in FIG. 3, when the optical information recording medium 1 is irradiated with a recording light (recording laser light) L1, the light absorbing layer 3 generates heat by absorbing the energy of the laser light L1, Thermal deformation occurs on the substrate 2 side and the pit 11
Is formed. In some cases, an optical change may occur in the light absorbing layer 3.

The light-transmitting substrate 2 is made of a material having a high transparency with respect to a laser beam having a refractive index of, for example, about 1.4 to 1.6 and mainly made of a resin having excellent impact resistance, for example, a resin. A glass plate, an acrylic plate, an epoxy plate, or the like is used.

The light absorbing layer 3 is a layer formed of a light absorbing substance (light absorbing substance) formed on the substrate 2, and is irradiated with a laser to generate heat, melting, sublimation, deformation or modification. It is. The light absorbing layer 3 is formed by uniformly coating the surface of the substrate 2 with a cyanine dye or the like dissolved by a solvent, for example, by a method such as spin coating. As long as the material used for the light absorbing layer 3 is a known optical recording material, the effects of the present invention can be obtained, but a light absorbing organic dye is preferable.
FIG. 4 is a structural formula of a benzo cyanine dye (benzoindodicarbocyanine) as a preferable example of a recording dye used in the present invention. FIG. 5 is a structural formula of an aminium salt compound (near infrared absorbing dye) as a preferred example of the light stabilizer used in the present invention.

As described above, the material used for the light absorbing layer 3 in the present invention has, for example, benzoindodicarbocyanine having the structure shown in FIG. Particularly, it is a cyanine dye having the N-alkyl chain (R1 in FIG. 4). By having this N-alkyl chain R1 as a side chain,
As a result of inducing steric hindrance as a cyanine dye molecule and reducing molecular crystallinity, the refractive index of the light absorbing layer 3 can be increased from about 2.5 to 2.7 to 2.8,
By reducing the thickness of the light absorbing layer 3 (average film thickness Dav, described later),
The recording sensitivity can be improved, the jitter can be reduced, the margin can be increased, and the degree of modulation can be further improved.

By designing the material not to contain chlorine (Cl), bromine (Br) or iodine (I) in the cyanine dye of the light absorbing layer, for example, as shown in FIG. PF6 containing fluorine (F) ^-,
BF4 @ ^-, SbF6 @ ^- by adopting any of the, improves the stability against high temperature and high humidity,
The corrosiveness of silver (Ag) used for the light reflection layer 4 and the like can be suppressed.

Further, the above-mentioned benzoindodicarbocyanine dye contains an aminium salt compound having an amino group (R2 in FIG. 5) as a stabilizer to improve light stability and heat stability. Can be.

Also, benzoindodicarbocyanine,
By containing a stabilizer containing an aminium salt compound at a weight ratio of 90:10 to 65:35,
The refractive index of the light absorbing layer 3 can be increased. Here, the content of the benzoindodicarbocyanine dye was 65%.
If the content is less than 10% by weight, it becomes impossible to obtain a sufficient refractive index and laser light absorption as a light absorbing layer corresponding to high-speed recording. Further, when the content of the aminium salt compound is 10
If the amount is less than% by weight, a sufficient light stability effect as a stabilizer cannot be obtained. Therefore, it is preferable to set the weight ratio of the benzoindodicarbocyanine dye to the aminium salt compound to 90:10 to 65:35 in order to obtain stable recording / reproducing characteristics during high-speed recording.

The light reflection layer 4 is a metal film, for example,
Gold, silver, copper, aluminum, or an alloy containing these is formed by a method such as an evaporation method or a sputtering method.

The protective layer 5 is formed of a resin having excellent impact resistance similar to that of the substrate 2. For example, an ultraviolet curing resin is applied by a spin coating method, and is irradiated with ultraviolet rays to be cured to form the resin.

As shown particularly in FIG. 2, when the groove width of the pre-groove 6 on the substrate 2 is Wsub and the inclination angle of the groove is Asub, 400 nm ≦ Wsub ≦ 5
It is desirable that 80 nm and 35 ° ≦ Asub ≦ 60 ° are satisfied. In order to obtain such a pre-groove 6, for example, the intensity of a laser light source for cutting used when creating a master (master) is increased, the shape of a lens is adjusted in order to control the focal point, or the cutting is performed. In this case, the rotation speed of the master is reduced.

In the optical information recording medium according to the present invention,
Regarding the groove width Wsub and the groove inclination angle Asub,
Optimizing the optical conditions by limiting to the above range,
By improving the recording sensitivity and reducing the optical interference between tracks, a tracking function corresponding to high-speed recording can be guaranteed, and a predetermined CD standard can be satisfied. That is, the groove width Wsub of the pre-groove 6 is 4
If the value is smaller than 00 nm, the area where the recording pits 11 are formed becomes small (thin), so that a sufficient contrast between a recorded portion and an unrecorded portion cannot be obtained at the time of reproduction. 60% as a satisfactory degree of modulation
It is difficult to secure the above. Also, the groove width W
When sub is greater than 580 nm, signal leakage of adjacent tracks, that is, deterioration of so-called crosstalk is caused, and as a result, it is difficult to secure wobble jitter of 6 μs or less required for high-speed recording.

If the groove inclination angle Asub of the pre-groove 6 is smaller than 35 °, the difference between the land 7 and the pre-groove 6 becomes indistinct, so that a stable tracking signal, that is, a push-pull signal (bright and dark difference) is generated. It is difficult to secure. Also, the groove inclination angle Asu
When b is greater than 60 °, the recording pits 11 are likely to be formed not only in the pre-groove 6 but also to the lands 7, and as a result, 6 μm required for high-speed recording is obtained.
It becomes difficult to secure wobble jitter of s or less, and it becomes difficult to control the speed in high-speed recording.

Conventionally, the groove inclination angle Asub is about 90
Although it is close to the degree, in the present invention, as described above, the inclination of the side wall surface of the pre-groove 6 is set to 35 ° ≦ Asub ≦ 60 °, or the opening portion is widened. That is, it is difficult to limit the irradiation range of the recording light L1 to only the pre-groove 6, and conventionally the recording light L1 is irradiated to the land 7 other than the pre-groove 6, so that the pits 11 Although there is a possibility that the groove is formed so as to overflow from the portion of the pit to the portion of the land 7, in the present invention, by considering the groove inclination angle Asub as described above, the pit 1 can be formed.
1 can be limited to the pregroove 6. FIG. 6 is a schematic cross-sectional view showing the state of formation of the pits 11 in comparison with the prior art and the present invention.
6 shows the case of the conventional pre-groove 6, and FIG. 6 (2) shows the case of the pre-groove 6 according to the present invention. FIG.
As shown in comparison with (1) and (2), conventionally, there was a possibility that the pit 11 was formed from the portion of the pre-groove 6 to the portion of the land 7.
1 can be limited to the pregroove 6.

The groove depth of the pre-groove 6 on the substrate 2, that is, the lands 7 located on the left and right of the pre-groove 6
When the depth from the first layer boundary 8 in the portion of the first layer boundary 8 to the bottom of the first layer boundary 8 in the portion of the pre-groove 6 is Dsub, the ratio of the groove width Wsub to the groove depth Dsub is It is desirable that 1.5 ≦ Wsub / Dsub ≦ 3.7. The groove width Wsub is a half value width (1/2 of the groove depth Dsub) with respect to the groove depth Dsub.
(The value of the width at the depth). Such a pregroove 6 can be easily obtained by operating the thickness of the photosensitive resin of the master (master), for example. As described above, by defining the ratio between the groove width Wsub and the depth Dsub, the pregroove 6 is made shallower than before and the groove wall is made gentler than before, so that the dye absorption area becomes smaller. The pits 11 can be clearly formed because they are wide and the periphery is clear.

If the ratio Wsub / Dsub is smaller than 1.5, the heat generated during the irradiation of the recording laser is likely to be accumulated in the light absorbing layer 3, resulting in an increase in thermal interference, which is necessary for high-speed recording. It is impossible to secure 35 ns or less as the RF jitter of the CD standard.
Since the area where the recording pits 11 are formed becomes small (thin), a sufficient contrast between a recorded portion and an unrecorded portion cannot be obtained during reproduction, and as a result, a modulation factor satisfying the CD standard is 60. % Is difficult to secure. If Wsub / Dsub is greater than 3.7, signal leakage of an adjacent track, that is, deterioration of so-called crosstalk is caused, and as a result, 6 μs required for high-speed recording is obtained.
It becomes difficult to secure the following wobble jitter,
At the same time, the optical distance Δn · d determined by the refractive index difference Δn before and after recording of the light absorbing layer and the film thickness d of the light absorbing layer becomes small. % Is difficult to secure.

The average thickness of the light absorbing layer 3 is defined as Dav. Here, the average film thickness Dav is a value obtained by dividing the dye cross-sectional area for one track pitch in the medium cross-section by the one track pitch length. (A) The film thickness per unit absorbance (nm / Abs) at the absorption peak in the film state of (b) is calculated, and in the state where the light absorbing layer is coated on the substrate, the (b) absorbance (Abs) at the absorption wavelength is calculated. By measuring, the result (a) × (b) can be obtained as an average film thickness. This average film thickness Dav is reduced to 4
0 nm ≦ Dav ≦ 80 nm, and more preferably, 56 nm ≦ Dav ≦ 72 nm.

In the case of such an optical information recording medium, the optical distance Δn · d determined by the refractive index difference Δn of the light absorbing layer before and after recording and the optical absorption layer thickness d is larger. However, if the average thickness Dav of the light absorbing layer 3 is smaller than 40 nm, it is difficult to secure 60% or more as the modulation degree satisfying the CD standard. When the average film thickness Dav is larger than 80 nm, heat generated at the time of irradiating the recording laser is likely to be accumulated in the light absorbing layer 3, resulting in an increase in thermal interference.
It is impossible to secure 35 ns or less as the RF jitter of the CD standard required at the time of high-speed recording.

Lands 7 located on the left and right of pregroove 6
Layer boundary between the light absorbing layer 3 and the light reflecting layer 4 at the portion
From the layer boundary 9) of the pregroove 6
The depth at the bottom of the layer boundary 9 of the first layer is defined as Dabs, and the real part of the complex refractive index of the substrate 2, that is, the real part of the complex refractive index of the layer located on the substrate 2 side of the first layer boundary 8 (these layers). When there are a plurality of layers including the substrate 2, the real part of the complex refractive index of each layer is nsub, the real part of the complex refractive index of the light absorbing layer 3 is nabs, and the reproduction light (reproduction laser light ) The wavelength of L2 is λ, and the optical phase difference between the pre-groove 6 portion and the land 7 portion of the reproduction light reflected by the light reflection layer 4 is △ S = 2Dsub ｛nsub-nabs (1
−Dabs / Dsub)｝ / λ, 0.15 ≦ {S
It is desirable that ≦ 0.55.

The optical phase difference ΔS is determined by the optical position between the pre-groove 6 and the land 7 of the reproduction light L 2 irradiated from the substrate 2 and reflected by the light reflection layer 4. It is a difference. Hereinafter, description will be made with reference to FIG. The film thickness of the light absorbing layer 3 at the pregroove 6 is defined as Dgr.
The film thickness of the light absorption layer 3 at the land 7 is Dln. First, when light is irradiated from the substrate 2 side, the second layer boundary 9 in the land 7 portion with respect to the first layer boundary 8 of the light absorbing layer 3 in the pre-groove 6 on the substrate 2 side. The optical distance to is represented by nsub.Dsub + nabs.Dln. The light absorbing layer 3 in the pre-groove 6
The optical distance to the second layer boundary 9 in the portion of the pregroove 6 with respect to the first layer boundary 8 on the substrate 2 side is represented by nabs · Dgr. Therefore, assuming that the optical distance difference is F, F = (nsub.Dsub + nabs.Dln) -nabs.Dgr = nsub.Dsub-nabs (Dgr-Dln). At this time, Dgr + Dabs = Dln + Dsub, that is, Dgr-Dln = Dsub-Dabs. Therefore, F = nsub.Dsub-nabs (Dsub-Dabs). Therefore, when the reproduction light L2 is irradiated from the substrate 2 side,
The optical phase difference ΔS = 2 of the reproduction light L2 between the portion of the pre-groove 6 and the portion of the land 7 reflected by the light reflection layer 4
F / λ is represented by 2Dsub {nsub-nabs (1-Dabs / Dsub)} / λ.

Here, particularly, the tracking error signal, that is, the push-pull signal is generated by the optical phase difference Δ △.
Is known to be dependent on
And the optical phase difference ΔS between the portion of FIG.
With a value smaller than 15, it is difficult to secure a stable tracking signal, that is, a push-pull signal, because the amount of diffraction of light detected by the detector is small. When the optical phase difference ΔS is larger than 0.55,
On the other hand, since the amount of light diffraction is large, it is not possible to secure a reflectance of 70% or more as a CD standard.

[0038]

Next, an embodiment of an optical information recording medium according to the present invention will be described. Example 1 A groove width Wsub = 460 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 45 measured by AFM (intermolecular force microscope) measurement, respectively.
°, a spiral pre-groove having a pitch of 1.5 μm, a thickness of 1.2 mm, an outer diameter of 120 mm, and an inner diameter of 15 m
m polycarbonate substrate was molded by an injection molding method. At this time, Wsub / Dsub = 2.2. As a recording dye, 80 parts by weight of a dye (benzoindodicarbocyanine) having a structure shown in FIG. 7, which is a benzo-based cyanine dye,
As a light stabilizer, 20 parts by weight of a near-infrared absorbing dye having a structure shown in FIG. 8, which is an aminium salt compound, is dissolved in diacetone alcohol at 25 g / liter, and the solution is applied to a substrate by spin coating. Average thickness Dav = 64
A light absorption layer of nm was formed. That is, in the benzo cyanine dye in the structural formula of FIG. 4, Y = H and R1 = -CH2
—CH 2 —CH (CH 3) 2, X ⁻ = PF 6 ^−, and in the aminium salt compound in the structural formula of FIG. 5, R 2 = −N (−
CH2-CH2-CH2-CN) 2, X - = PF6 - is as. In the measurement environment (temperature 23 ° C, humidity 50% RH)
In the above, the refractive index nsub =
1.58, the refractive index of the light absorbing layer nabs = 2.6, A
According to FM measurement, the groove depth Dabs = 11 on the dye film
It was 8 nm.

A light reflecting layer made of an Ag (silver) film having a thickness of 80 nm was formed on the substrate with the dye film by RF sputtering. Further, on this light reflection layer, an ultraviolet curable resin (SD-21, manufactured by Dainippon Ink and Chemicals, Inc.)
1) was spin-coated, and this was irradiated with ultraviolet rays to be cured, thereby forming a protective layer having a thickness of 6 μm.

A recording device (DDU100, manufactured by Pulstec) using a laser beam having a wavelength of 784 nm and a lens aperture ratio of NA = 0.50 was applied to the optical information recording medium thus obtained.
0), a reference linear velocity (for example, a linear velocity of 1.2 m /
In order to obtain the EFM signal of the Orange Book standard (CD-R standard) at the time of reproduction according to s), the EFM signal is recorded on the entire surface of the disk at a linear velocity of 14.4 m / s, which is 12 times that of the EFM signal. Reproduction evaluation was performed at a speed of 1.2 m / s. In this optical information recording medium, ΔS = 0.250, the push-pull signal in the unrecorded state was 0.09, and the wobble jitter in the unrecorded state was 4.3 μs. At this time, I11
/Itop=0.77, I3 / Itop = 0.35, and B
LER is 1.3 cps and RF jitter is 31 ns
35 ns as CD standard RF jitter
Good characteristics satisfying the following were obtained. However, "Ito
"p" is the maximum amount of reflected light in the CD reproduction signal.
"I11" is the difference between the amount of reflected light that is diffracted by the longest pit recorded in the pre-groove where recording is performed and returns to the objective lens, and the amount of reflected light that is reflected by non-pit portions and returns to the objective lens. Is an optical modulation component corresponding to "I3" is the difference between the amount of reflected light that is diffracted by the shortest pit recorded in the pre-groove where recording is performed and returns to the objective lens, and the amount of reflected light that is reflected by non-pit portions and returns to the objective lens. Is an optical modulation component corresponding to At this time, the maximum reflectance Rtop of the signal after recording is Rtop = 68% R, and the wobble jitter is 4.
5 μs.

Further, an EFM signal was recorded at a normal speed at a linear velocity of 1.2 m / s using a disk prepared in the same manner as this optical information recording medium, and the reproduction was evaluated in the same manner as described above. Itop = 0.658, I3 / Itop = 0.
31 and BLER were 2.1 cps, and good characteristics of RF jitter of 35 ns or less were obtained in all signal regions. At this time, the maximum reflectance Rtop of the signal after recording was Rtop = 69% R, and the wobble jitter was 4.3 μs.

According to the above embodiment, the optical information recording medium capable of high-speed recording is required due to the thinning of the light-absorbing layer. It is possible to provide an optical information recording medium having good characteristics such as I11 / Itop, that is, modulation factor when the EFM signal is recorded and reproduced at a normal speed at 0.2 m / s at high speed. Hereinafter, examples and comparative examples will be described in which attention is paid to the wobble jitter and the degree of modulation (I11 / Itop) at the time of non-recording, which are important characteristics in high-speed recording.

Example 2 Using the polycarbonate material of Example 1, a groove width Wsub = 400 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 45.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 1.95. Others are the same as the first embodiment. The optical information recording medium thus obtained was used in Example 1.
Was evaluated in the same manner as described above. That is, the wobble jitter before recording is 3.6 μs. When the EFM signal is recorded at a normal speed at a linear velocity of 1.2 m / s on this optical information recording medium and the reproduction is evaluated, I11 / Itop = 0. .611, and thus a good recording / reproducing characteristic was obtained as an optical information recording medium corresponding to high-speed recording.

Example 3 Using the polycarbonate material of Example 1, a groove width Wsub = 580 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 45.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 2.8. Others are the same as the first embodiment. The optical information recording medium thus obtained was evaluated in the same manner as in Example 1. That is, the wobble jitter before recording was 5.6 μs, and the optical information recording medium was recorded with an EFM signal at a normal speed of 1.2 m / s at a normal speed and evaluated for reproduction. .735, and thus good recording / reproducing characteristics were obtained as an optical information recording medium compatible with high-speed recording.

Comparative Example 1 Using the polycarbonate material of Example 1, a groove width Wsub = 380 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 45.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 1.85. Others are the same as the first embodiment. The optical information recording medium thus obtained was used in Example 1.
Was evaluated in the same manner as described above. That is, although the wobble jitter at the time of non-recording is 3.2 μs, which is a good characteristic,
An EFM signal was recorded at a normal speed at a linear velocity of 1.2 m / s on this optical information recording medium, and the reproduction was evaluated.
top = 0.587, CD standard modulation degree 60%
I could not satisfy the above.

Comparative Example 2 Using the polycarbonate material of Example 1, a groove width Wsub = 640 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 45.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 3.1. Others are the same as the first embodiment. The optical information recording medium thus obtained was evaluated in the same manner as in Example 1. That is, when this optical information recording medium was recorded with an EFM signal at a linear speed of 1.2 m / s at a normal speed and evaluated for reproduction, I11 / Itop = 0.718, and a modulation factor of 60% or more as a CD standard Is satisfied, but the wobble jitter at the time of non-recording is 6.
4 μs, 6 μs required for high-speed recording
The following could not be satisfied.

Example 4 Using the polycarbonate material of Example 1, a groove width Wsub = 460 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 60.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 2.2. Others are the same as the first embodiment. The optical information recording medium thus obtained was evaluated in the same manner as in Example 1. That is, the wobble jitter before recording is 5.5 μs. When the EFM signal is recorded at a normal speed at a linear velocity of 1.2 m / s on this optical information recording medium and the reproduction is evaluated, I11 / Itop = 0. 691 and good recording / reproducing characteristics as an optical information recording medium compatible with high-speed recording were obtained.

Example 5 Using the polycarbonate material of Example 1, a groove width Wsub = 460 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 35.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 2.2. Others are the same as the first embodiment. The optical information recording medium thus obtained was evaluated in the same manner as in Example 1. That is, the wobble jitter before recording was 3.8 μs, and the EFM signal was recorded at a normal speed of 1.2 m / s on this optical information recording medium at a normal speed, and the reproduction was evaluated. .624, and good recording and reproducing characteristics were obtained as an optical information recording medium compatible with high-speed recording.

Comparative Example 3 Using the polycarbonate material of Example 1, a groove width Wsub = 460 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 65.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 2.2. Others are the same as the first embodiment. The optical information recording medium thus obtained was evaluated in the same manner as in Example 1. That is, although the wobble jitter at the time of non-recording is a good characteristic of 3.2 μs, the optical information recording medium was recorded at a normal speed of an EFM signal at a linear velocity of 1.2 m / s, and evaluated for reproduction. I11 / Ito
p = 0.702, which can satisfy the modulation factor of 60% or more which is the CD standard, but the wobble jitter at the time of non-recording becomes 6.7 μs, which is less than 6 μs required for high-speed recording. Could not be met.

Comparative Example 4 Using the polycarbonate material of Example 1, a groove width Wsub = 460 nm, a groove depth Dsub = 205 nm, and a groove inclination angle Asub = 30.
A substrate on which a spiral pregroove having a pitch of 1.5 μm was formed by an injection molding method. At this time W
sub / Dsub = 2.2. Others are the same as the first embodiment. The optical information recording medium thus obtained was evaluated in the same manner as in Example 1. That is, although the wobble jitter at the time of non-recording is a good characteristic of 3.2 μs, the optical information recording medium was recorded at a normal speed of an EFM signal at a linear velocity of 1.2 m / s, and evaluated for reproduction. I11 / Ito
p was 0.583, and the modulation factor of 60% or more as a CD standard could not be satisfied.

Example 6 Using the substrate of Example 1, 80 parts by weight of a benzo-based cyanine dye (benzoindodicarbocyanine) as in Example 1 and 20 parts by weight of an aminium salt compound as a light stabilizer were used. The solution was dissolved in diacetone alcohol at 25 g / liter, and the solution was applied to a substrate by spin coating to form a light absorption layer having an average film thickness Dav = 56 nm. The optical information recording medium thus obtained is subjected to a reference linear velocity (for example, linear velocity 1.
Orange Book Standard (CD-
In order to obtain an EFM signal in the R standard, an EFM signal is recorded on the entire surface of the disk at a linear velocity of 14.4 m / s, which is 12 times that of the EFM signal, and is reproduced and evaluated by the same machine at a linear velocity of 1.2 m / s. As a result, the RF jitter is 28 ns,
Good characteristics satisfying the CD standard of 35 ns or less were obtained. When the EFM signal was recorded at a normal speed at a linear velocity of 1.2 m / s and evaluated for reproduction, I11 / Itop =
0.611, which can satisfy the modulation factor of 60% or more, which is the CD standard.

Example 7 Using the substrate of Example 1, 80 parts by weight of a benzo-based cyanine dye (benzoindodicarbocyanine) similar to Example 1 and 20 parts by weight of an aminium salt compound as a light stabilizer were used. The solution was dissolved in diacetone alcohol at 25 g / liter and applied to a substrate by spin coating to form a light absorption layer having an average film thickness Dav = 72 nm. The optical information recording medium thus obtained is subjected to a reference linear velocity (for example, linear velocity 1.
Orange Book Standard (CD-
In order to obtain an EFM signal in the R standard, an EFM signal is recorded on the entire surface of the disk at a linear velocity of 14.4 m / s, which is 12 times that of the EFM signal, and is reproduced and evaluated by the same machine at a linear velocity of 1.2 m / s. As a result, the RF jitter is 33 ns,
Good characteristics satisfying the CD standard of 35 ns or less were obtained. When the EFM signal was recorded at a normal speed at a linear velocity of 1.2 m / s and evaluated for reproduction, I11 / Itop =
0.769, which can satisfy the modulation factor of 60% or more, which is the CD standard.

(Comparative Example 5) Using the substrate of Example 1, 80 parts by weight of the same benzo-based cyanine dye (benzoindodicarbocyanine) as in Example 1, and 20 parts by weight of an aminium salt compound as a light stabilizer were used. Was dissolved in diacetone alcohol at 25 g / liter, and the solution was applied to a substrate by spin coating to form a light absorption layer having an average film thickness Dav = 52 nm. The optical information recording medium thus obtained is subjected to a reference linear velocity (for example, linear velocity 1.
Orange Book Standard (CD-
In order to obtain an EFM signal according to the R standard, an EFM signal is recorded on the entire surface of the disk at a linear velocity of 14.4 m / s, which is 12 times that of the EFM signal. As a result, the RF jitter is 26 ns,
Although it can satisfy the CD standard of 35 ns or less, EFM signals are recorded at a normal speed at a linear velocity of 1.2 m / s and evaluated for reproduction.
9, indicating that the modulation factor of 60% or more, which is the CD standard, could not be satisfied.

Comparative Example 6 Using the substrate of Example 1, 80 parts by weight of the same benzo-based cyanine dye (benzoindodicarbocyanine) as in Example 1, and 20 parts by weight of an aminium salt compound as a light stabilizer were used. Was dissolved in diacetone alcohol at 25 g / liter, and the solution was applied to a substrate by spin coating to form a light absorption layer having an average film thickness Dav = 76 nm. The optical information recording medium thus obtained was recorded with an EFM signal at a normal speed of 1.2 m / s at a normal speed in the same manner as in Example 1, and evaluated for reproduction.
top = 0.793, the CD standard modulation degree 60%
Although the above can be satisfied, the linear velocity is 12 times that of the orange book standard (CD-R standard) so that an EFM signal in the Orange Book standard (CD-R standard) can be obtained at the time of reproduction at a reference linear velocity (for example, a linear velocity of 1.2 m / s). An EFM signal was recorded on the entire surface of the disk at 14.4 m / s, and the linear velocity was 1.2 m / sec.
When the reproduction evaluation was performed at s, the RF jitter was 36 ns.
As a result, the CD standard of 35 ns or less could not be satisfied.

As described above, the average thickness Dav of the light absorbing layer is set to 5
By setting the range of 6 nm ≦ Dav ≦ 72 nm,
Even when recording is performed on the optical information recording medium at a linear velocity of 14.4 m / s or more, which is 12 times the reference linear velocity of 1.2 m / s, stable recording / reproducing characteristics can be obtained.
In the case of an optical information recording medium compatible with recording at a linear velocity slower than twice, the average thickness Dav of the light absorbing layer should be 40 nm ≦ Dav.
It is also possible to set in the range of ≦ 80 nm.

[0056]

As described above, according to the present invention, by limiting the groove width Wsub and the groove inclination angle Asub within a predetermined range, characteristics such as RF jitter are sufficiently good even at high speed recording. An optical information recording medium having a sufficient modulation degree can be provided.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of an optical information recording medium 1 according to the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the optical information recording medium 1 before recording.

FIG. 3 is a longitudinal sectional view of a main part of the optical information recording medium 1 after recording.

FIG. 4 is a structural formula of a benzo-based cyanine dye (benzoindodicarbocyanine) as a preferred example of a recording dye used in the present invention.

FIG. 5 is an aminium salt compound (near-infrared absorbing dye) as a preferred example of the light stabilizer used in the present invention.
Is a structural formula.

FIG. 6 is a schematic cross-sectional view showing a state in which pits 11 are formed in comparison with a conventional example and the present invention.

FIG. 7 shows a benzo-based cyanine dye (benzoindodicarbocyanine) used as a recording dye in Example 1
Is a structural formula.

8 is a structural formula of an aminium salt compound (near-infrared absorbing dye) used as a light stabilizer in Example 1. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical information recording medium 2 Translucent substrate 3 Light absorption layer 4 Light reflection layer 5 Protective layer 6 Pregroove 6W Wobble of pregroove 6 Land 8 First layer boundary between substrate 2 and light absorption layer 3 9 second layer boundary between light absorption layer 3 and light reflection layer 4 10 third layer boundary between light reflection layer 4 and protection layer 5 11 pit Groove width of pregroove 6 on Wsub substrate 2 The groove inclination angle of the pre-groove 6 on the Asub substrate 2 From the first layer boundary 8 between the light absorbing layer 3 and the substrate 2 at the portion of the Dsub land 7, the bottom of the first layer boundary 8 at the portion of the pre-groove 6 (Groove depth) From the second layer boundary 9 between the light absorption layer 3 and the light reflection layer 4 in the portion of the Dabs land 7, the depth of the bottom of the second layer boundary 9 in the portion of the pre-groove 6 Nsub is located closer to the substrate 2 than the first layer boundary 8 between the light absorbing layer 3 and the substrate 2 The real part of the complex refractive index of N abs The real part of the complex refractive index of the light absorbing layer 3 Dav The average film thickness of the light absorbing layer 3 Dgr The film thickness of the pre-groove 6 of the light absorbing layer 3 Dln The land 7 of the light absorbing layer 3 Λ wavelength of reproduction light ΔS optical phase difference L1 laser light for recording L2 laser light for reproduction

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41M 5/26 B41M 5/26 Y F term (Reference) 2H111 EA03 EA12 EA22 EA25 EA31 FA01 FA39 FB43 FB63 5D029 JA04 JB35 JC06 WB03 WB11 WB17 WD12

Claims (7)

[Claims] 1. A substrate having translucency and formed with a pre-groove, a light absorbing layer provided on the substrate and absorbing recording light by laser light, a laser light absorbing layer provided on the light absorbing layer, An optical information recording medium for recording information by irradiating the light absorbing layer with the recording light, wherein a groove width of the pre-groove on the substrate is Wsub. An optical information recording medium, wherein when the groove inclination angle is Asub, 400 nm ≦ Wsub ≦ 580 nm and 35 ° ≦ Asub ≦ 60 °. 2. The optical information recording medium according to claim 1, wherein when a groove depth of said pre-groove on said substrate is Dsub, 1.5 ≦ Wsub / Dsub ≦ 3.7. . 3. The light-absorbing layer has a light-absorbing substance composed of a benzoindodicarbocyanine dye having the following structural formula, and when the average thickness of the light-absorbing layer is Dav, 40 nm ≦ Dav ≦ 80 nm. The optical information recording medium according to claim 1, wherein: Embedded image 4. The light-absorbing layer has a light-absorbing substance composed of a benzoindodicarbocyanine dye having the following structural formula, and when the average thickness of the light-absorbing layer is Dav, 56 nm ≦ Dav ≦ 72 nm. The optical information recording medium according to claim 1, wherein: Embedded image 5. The optical information recording medium according to claim 3, wherein the light absorbing layer contains an aminium salt compound having the following structural formula as a stabilizer. Embedded image 6. A depth of the bottom of the layer boundary in the pre-groove portion from the layer boundary between the light absorption layer and the light reflection layer in a land portion located on the left and right of the pre-groove is Dabs. The real part of the complex refractive index of the substrate is nsub, the real part of the complex refractive index of the light absorbing layer is nabs, the wavelength of the reproducing light is λ, and the reproducing light reflected by the light reflecting layer is The optical phase difference between the pregroove portion and the land portion is {S = 2Dsub {nsub-nabs (1-Dabs / Dsub)}.
2. The optical information recording medium according to claim 1, wherein 0.15 ≦ △ S ≦ 0.55 when / λ is satisfied. 7. When a reference linear velocity at the time of recording on the optical information recording medium is Vm / s, a linear velocity n · Vm / s
The optical information recording medium according to claim 4, wherein recording is possible with s (where n is an integer of 12 or more).