JP5108343B2 - Optical recording medium - Google Patents

Description

The present invention relates to an optical recording medium which is manufactured using a stun path (optical information recording medium). Application fields of the present invention include, for example, DVD + R discs, DVD-R discs, HD DVD-R discs, and BD-R discs.

  Various types of recording media such as CD (Compact Disc), MD (Mini Disc), and DVD (Digital Versatile Disc) have been proposed as optical recording media. These optical recording media are generally formed on a light-transmitting substrate made of PC (polycarbonate) or the like, for example, grooves (guide grooves), pits, etc. along the recording track, on which, for example, a reflective layer, Various recording layers, protective layers, and the like are formed.

  By the way, as a prior invention related to the present invention, there are those described in Patent Documents 1 to 5 below. In particular, Patent Document 5 discloses an optical recording medium in which a land pre-pit is constituted by a meandering portion that is a part of a groove.

  Conventionally, in a DVD-R or the like using a dye material as a recording layer, a so-called land pre-pit (LPP) for forming a pit in the land portion corresponding to the wobble amplitude of the groove is provided. A format that performs high-precision positioning at the time of data recording using pits) or acquires a recording address or other information necessary for recording is employed (see, for example, Patent Document 1 and Patent Document 2).

  However, in DVD-R, the deterioration of PI (Parity of Inner-code) error due to the provision of this LPP is a problem. As a countermeasure against this, for example, a format that specifically reduces the shape of the LPP is conceivable, but it is difficult to reduce the modulation degree (LPPb) of the LPP itself and to ensure the stable performance of the AR characteristics (reproduced waveform characteristics after recording). It becomes.

1 to 3 are schematic views schematically showing the shape of the land pre-pit 20 formed on the substrate of the optical recording medium. In FIG. 1 to FIG. 3, the appearance of the wobbling of the groove is omitted and drawn linearly in consideration of the visibility of the drawings.
FIG. 1 shows an example in which the land pre-pit 20 is formed independently at the approximate center of the land 11.
FIG. 2 shows an example in which the land pre-pit 20 is formed so as to be shifted to the inner peripheral side.
FIG. 3 shows an example in which the land pre-pit 20 is constituted by a meandering portion which is a part of the groove 12.
Examples are shown in Patent Document 3 (in the case of FIG. 1), Patent Document 4 (in the case of FIG. 2), and Patent Document 5 (in the case of FIG. 3).

With respect to the size of the land prepit 20, as shown in FIGS. 1 to 3, the length of the land prepit in the track direction is Lw, and the length of the land prepit in the direction perpendicular to the track direction is Aw.
In general, when manufacturing a substrate in which land pre-pits are independently formed at substantially the center of the land 11 as shown in FIG. 1 or by shifting the land pre-pits toward the inner peripheral side as shown in FIG. In the case of manufacturing a manufactured substrate, an optical recording medium master (stamper) used is a photoresist master that is cut using a laser beam for forming land prepits separately from a laser beam for forming grooves. It is produced by transcription. As described above, a method for producing a master for an optical recording medium by cutting a photoresist master using two laser beams, ie, a laser beam for forming a groove and a laser beam for forming a land prepit, is described in “Two-beam cutting method”. Sometimes called.

  On the other hand, as shown in FIG. 3, when manufacturing a substrate in which land prepits are formed by meandering portions that are a part of a groove, an optical recording medium master used for manufacturing the substrate has a single laser beam. It is produced by transfer of a photoresist master disc cut using the. In this case, in the portion where the land pre-pit is to be formed, the irradiation position of the laser beam is largely shifted to the outer peripheral side, whereby the meandering portion which is a part of the groove can be made the land pre-pit. In this way, a method of cutting a photoresist master using a single laser beam to produce an optical recording medium master is sometimes referred to as a “one-beam cutting method”.

  Thus, when manufacturing an optical recording medium having land pre-pits, an optical recording medium master used for manufacturing the substrate can be manufactured by a two-beam cutting method or a one-beam cutting method. A recording layer and a reflective layer are produced on a substrate formed by injection molding from such an optical recording medium master (stamper) to produce an optical information recording medium.

  Here, when the substrate is molded, the transferability of the outer peripheral portion is often insufficient. In this case, there is a possibility of being out of specification in terms of groove characteristics and the like at the outer periphery. In particular, when a substrate is formed using a stamper in which meandering land prepits are formed by a one-beam cutting method, the inner land prepits and the outer land prepits have the same length on the stamper. If formed, when the land prepit Lw (length in the track direction) is compared between the inner peripheral portion and the outer peripheral portion on the substrate, the length becomes shorter at the outer peripheral portion, and the LPP signal at the outer peripheral portion becomes smaller. Therefore, troubles are likely to occur when reading the address position.

JP 2000-353342 A JP 2001-291283 A JP 2002-32918 A JP 2001-118288 A JP 2002-25121 A

The present invention has been made in view of the above circumstances of the prior art, and its main object is to provide an optical recording medium that comprehensively satisfies various parameters such as LPP signal, jitter, and PI error.
Accordingly, another object of the present invention is to provide a process for producing an optical recording medium by the substrate obtained by using the injection molding stun path capable of producing such an optical recording medium.

The above problem is solved by the following inventions.

A stamper for producing an optical recording medium having a substrate c Oburugurubu and land pre-pits are formed, at least the wobble groove and the land pre-pits are formed on the surface thereof, said land prepits said wobble groove The length Lw becomes longer from the inner periphery to the outer periphery when the length of the land prepit in the direction along the wobble groove is Lw. A substrate formed by injection molding using a stamper, a squarylium dye represented by the following chemical formula (1) and a formazan chelate dye represented by the following chemical formula (2) at a mixing ratio of 7: 3. an inner peripheral portion in the land pre-pit and a recording layer containing, formed on said stamper (R = 24 mm) Where Lw_in is the length in the direction along the wobble groove and Lw_out is the length in the direction along the wobble groove at the outer periphery (R = 58 mm): Lw_out / Lw_in is 1 .10 or more and 1.30 or less, and (Lw_out + Lw_in) / 2 is 850 nm or more and 1150 nm or less, and the substrate injection-molded using the stamper has an inner peripheral portion (R = 24 mm) in the land prepit. Lw_out is a ratio of Lw_out to Lw_in, where Lw_in is the length in the direction along the wobble groove at L), and Lw_out is the length along the wobble groove in the outer periphery (R = 58 mm): Lw_out / Lw_in Is 1.00 or more and 1.10 or less, and (Lw_out + Lw_in ) / 2 is 700 nm or more and 1150 nm or less .

  According to the present invention, for example, a DVD-R having a jitter of less than 8%, a PI error of less than 280, a BLER of less than 5%, and an AR characteristic of 15 or more can be easily manufactured with good yield.

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to the following embodiments and examples, and can be applied to other optical recording media having different recording layer materials and configurations, and stampers for manufacturing optical recording media. Various modifications and changes can be made to various optical recording media provided with pits without departing from the configuration of the present invention.

<Stamper manufacturing process>
First, an example of a stamper manufacturing process used in the present invention will be described with reference to the drawings. 4A to 4F are process diagrams showing the manufacturing process of a stamper for manufacturing an optical recording medium similar to the conventional one.
First, as shown in FIG. 4A, a photosensitive layer 62 such as a photoresist is applied to a master substrate 61 made of glass or the like whose surface has been cleaned through a coupling agent (not shown). Using the optical recording apparatus shown in FIG. 5 to be described later, a latent image is formed by performing exposure corresponding to the shape of the pit shape corresponding to information, or in the case where a groove is provided on the optical recording medium. Then, without passing through the development process, as shown in 4 (B), a groove pattern 63 a and a land pre-pit pattern 63 b corresponding to a predetermined information signal are formed to produce a so-called glass master.

And after covering the uneven | corrugated pattern surface of this glass original disc, ie, a signal formation surface, and forming a thin electroconductive film by the electroless plating method etc., as shown in FIG.4 (C) by an electroplating method etc. Layer 64a is formed. Thereafter, as shown in FIG. 4D, the plating layer is peeled off to form a stamper 64 (so-called master stamper).
Then, after applying a predetermined release agent or the like, similarly, electroless plating and electroplating are applied to the stamper 64 to form a so-called mother stamper 65 to which the concavo-convex pattern is transferred as shown in FIG. Further, a sun stamper 66 in which a groove pattern 66a and a land pre-pit pattern 66b are formed as shown in FIG. 4F can be obtained from the mother stamper 65 by the same process. By preparing a large number of the sun stampers 66, an optical recording medium manufacturing substrate can be manufactured with high productivity by an injection molding method, a 2P method, or the like.

In addition, the optical recording with respect to the above glass master can be performed by a general optical recording apparatus having a schematic configuration shown in FIG.
The Kr laser oscillator 201 generates an exposure light beam. The light beam emitted from the laser oscillator 201 is reflected by the reflecting mirrors 203 and 204 and enters the objective lens 205, and the light beam that has passed through the objective lens 205 is irradiated onto the recording master disk 206. An AO modulator (Acoustic Optical Modulator) 207a is provided between the reflecting mirrors 202 and 203, and signals such as video signals and audio signals to be recorded supplied from the FM modulator 207 are optically transmitted by the AO modulator 207a. The beam is modulated in response to the signal.

  As the AO modulator 207a, a wedge prism, an AOD (a reverberant optical deflector), or a rotating mirror having a non-parallel surface as an exit / incident surface is used. The AOD uses, for example, the fact that the diffraction angle of the first-order diffracted light is changed by inputting a high-frequency electric signal having a center frequency of about 300 MHz and changing the center frequency. On the other hand, as a device using a wedge prism and a rotating mirror, a driving system such as a DC motor, a stepping motor, or a piezo element that rotationally drives them is controlled to use the deflection of the refracted light and reflected light. The positive photoresist layer on the rotating recording master 206 is exposed by the modulated exposure light beam. In addition, a light beam expander 208 is provided between the reflecting mirrors 203 and 204, so that the diameter of the light beam is enlarged so that the beam is incident on the entire lens of the objective lens 205.

  On the other hand, a focus servo optical system including a HeNe laser oscillator 210 is used in an optical disc cutting apparatus in order to drive the objective lens 205 and perform focus servo. The light beams emitted from the laser oscillator 210 are reflected by the reflection mirror 211 and the dichroic mirror 212, merge with the exposure light beam, and enter the reflection mirror 204. The light beam that has passed through the objective lens 208 is irradiated onto the recording master disk 206. Note that the wavelength and intensity of the focusing light beam of the laser oscillator 210 are selected so that the recording master 206 is not exposed. A polarization beam splitter 213 is provided between the reflection mirror 211 and the dichroic mirror 212, and the reflected light from the recording master 206 passes through the objective lens 205 and is reflected by the reflection mirror 204 and the dichroic mirror 212, and the polarization beam splitter 213. And is supplied to the four-divided light detector 215 through the cylindrical lens 214. Each output signal of the optical detector 215 is supplied to the focus servo control circuit 216, and the focus servo control circuit 216 drives the actuator 217 of the objective lens 205 in accordance with each output signal of the optical detector 215.

  Furthermore, a spindle servo circuit 221 that controls the rotation of a spindle motor 220 that rotates a turntable 219 that holds and rotates the recording master 206, and an optical head that carries an optical system including the objective lens 205, etc. The optical disc cutting apparatus is provided with an optical head feed servo circuit 223 for controlling the rotation of the drive motor 222 that is moved in the radial direction.

  In such an optical disc cutting apparatus, the positive type of the recording master disc is controlled by one light beam modulated by the wobbling signal on which the LPP signal is superimposed under the control of the oscillator 201, the modulator 207, and the servo systems 216, 221, and 223 by the controller 260. The photoresist layer is irradiated and exposed, and the exposed portion of the positive photoresist layer is etched and developed as pits to form tracks.

  First, the recording master disk 206 in which the photoresist layer 206b is formed on the main surface of the glass disk 206a is placed on the turntable 219 of the laser cutting apparatus in the optical disc cutting apparatus. Thereafter, the table is rotated, and as shown in FIG. 6, the light beam La is moved relative to the original disk in a spiral or concentric manner, and the cutting light beam La modulated by the wobbling signal superimposed with the LPP signal is applied to the photoresist. The track 206 is condensed on the layer 206 b, the spot of the cutting light beam is deviated in a direction perpendicular to the groove track 12, and the deviated spot is returned to the original position of the groove track 12, thereby producing a latent image of the track. Formed on the photoresist layer 206b. At this time, since the LPP signal superimposed wobbling signal is used, the cutting light beam spot oscillates with a second amplitude larger than the first amplitude at regular intervals.

Next, the exposed photoresist master is mounted on a developing device and developed to remove the latent image portion. As shown in FIG. 3, a portion meandering from the side surface of the groove track is formed as a land pre-pit 20 on the master disk.
Next, after fixing by post-baking, a conductive film such as nickel or silver is formed on the photoresist layer 206b by sputtering or vapor deposition, for example, a nickel stamper is formed by nickel electroforming, and the stamper is formed on a glass plate. Separated from 206a, a nickel stamper is obtained. A replica of the resin optical disk substrate having the same pre-information as shown in FIG. 3 is produced by the stamper, for example, by an injection molding method or a so-called 2P method.

In addition, this time, by adjusting the time during which the cutting light beam spot in FIG. 6 is biased in the direction perpendicular to the groove track 12 during the exposure master production, Lw in FIG. 3 is increased from the inner periphery to the outer periphery. I did .
In FIG. 3, only one groove track 12 having a land pre-pit having a length Lw is shown. However, as a whole stamper, a large number of groove tracks are naturally formed, and these groove tracks have. Comparing the length Lw of the land pre-pits, it is characterized in that it becomes longer in order from the inner periphery to the outer periphery of the stamper. That is, it can be said that the stamper according to the embodiment of the present invention is an improvement of the stamper having the structure shown in FIG. 3 (see Table 1 below).
As a result, when a molded plate is produced using the produced stamper, when comparing the Lw (length in the track direction) of the land prepits in the inner peripheral portion and the outer peripheral portion, the inner peripheral portion and the outer peripheral portion are compared. It was possible to solve the problem that the length became the same or more and the LPP signal at the outer peripheral portion became small, causing problems in reading the address position.

As a specific land pre-pit shape, the length in the direction along the wobble groove at the inner periphery (R = 24 mm) is Lw_in, and the length in the direction along the wobble groove at the outer periphery (R = 58 mm). the when the Lw_out, Lw_out / Lw_in 1.10 or more, have preferably be 1.30 or less. If the value is outside this range and smaller than 1.10, the LPP signal at the outer peripheral part becomes small, and it becomes easy to cause a trouble in reading the address position. If it exceeds 1.30, the jitter or PI error at the outer peripheral part, etc. It becomes easy to cause trouble.

Furthermore, (Lw_out + Lw_in) / 2 is 850nm or more, it is not preferable or less 1150 nm. If it is out of this range and smaller than 850 nm, the LPP signal becomes small in the plane, which tends to cause problems in reading the address position, and if it is larger than 1150 nm, it tends to cause problems in the plane due to jitter, PI error, and the like.

Further, Aw in FIG. 3, that is, (Aw (in) + Aw (out)) / 2 is preferably 100 or more and 200 nm or less (see Table 1 below). When attention is paid to an arbitrary land pre-pit, the Aw (in) indicates the value of Aw on the inner peripheral side, and the Aw (out) indicates the value of Aw on the outer peripheral side.
If Aw falls outside the above range and is smaller than 100 nm, the LPP signal will be small in the plane and it will be easy to cause troubles such as reading of the address position, and if it is larger than 200 nm, it will be easy to cause troubles due to jitter or PI error in the face. Become.

<Disk configuration>
An embodiment of the optical recording medium of the present invention will be described. The embodiment of the present invention is not limited to the one described below, and can be applied to a two-layer disc.

  The layer structure is as shown in FIG. Reference numeral 1 denotes a substrate, 2 denotes a recording layer made of an organic dye, 3 denotes a reflective layer, 4 denotes a protective layer, 5 denotes an adhesive layer, and 6 denotes a cover layer.

Hereinafter, other layer materials used in the optical information recording medium of the present invention will be specifically described.
[substrate]
The substrate must be transparent to the laser used when performing recording / reproduction from the substrate side, but need not be transparent when performing recording / reproduction from the recording layer side.
As the substrate material, for example, a polyester resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a polyolefin resin, a phenol resin, an epoxy resin, a polyimide resin such as a polyimide resin, glass, ceramic, metal, or the like can be used.
A tracking guide groove or guide pit and a preformat such as an address signal may be formed on the surface of the substrate. The groove shape is preferably groove depth: 1000 to 2000 mm and groove width (bottom width): 0.2 to 0.3 μm. In the case of spin coating, since the groove tends to be filled with a dye, the interface shape between the first recording layer and the first reflective layer is determined by this filling amount and the substrate groove shape, so that the interface reflection is reduced. The above range is suitable for use.

As the land pre-pit shape, the length in the direction along the wobble groove at the inner periphery (R = 24 mm) is Lw_in, and the length in the direction along the wobble groove at the outer periphery (R = 58 mm) is Lw_out. and when, Lw_out / Lw_in 1.00 or more, have preferably be 1.10 or less. If the value is outside this range and smaller than 1.00, the LPP signal at the outer peripheral portion becomes small, and problems such as reading of the address position are likely to occur. When it is larger than 1.10, it becomes easy to cause a malfunction due to jitter or PI error in the outer peripheral portion.

Furthermore, (Lw_out + Lw_in) / 2 is 700nm or more, it is not preferable or less 1150 nm. If it is outside this range and smaller than 700 nm, the LPP signal will be small in the plane and will likely cause problems in reading the address position, and if it is larger than 1150 nm, problems will likely be caused in the plane due to jitter, PI errors, and the like.

[Recording layer]
The recording layer causes an optical change due to the irradiation of the laser beam and records information by the change, and a material containing an organic dye as a main component is used as the material. Here, the main component means that it contains a sufficient amount of an organic dye necessary for recording and reproduction, but usually only an organic dye is used except for a small amount of additives that are appropriately added as necessary.

  Examples of organic dyes include azo, formazan, dipyrromethene, (poly) methine, naphthalocyanine, phthalocyanine, tetraazaporphyrin, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (in) (Dansylene), xanthene, triphenylmethane, azulene, tetrahydrocholine, phenanthrene, triphenothiazine dyes, or metal complexes thereof. Among these, azo (metal chelate) dye, formazan (metal chelate) dye, squarylium (metal chelate) dye, dipyrromethene (metal chelate) dye, trimethine cyanine dye, and tetraazaporphyrin dye are preferable.

  Cyanine dyes and squarylium metal chelate compounds have excellent performance as recording materials for DVDs.

As the cyanine dye compound, a conventionally used compound can be used as it is. Examples include materials disclosed in Japanese Patent No. 2594443, Japanese Patent No. 3698708, and Japanese Patent No. 3659922.
As the thermal decomposition characteristics, the above dyes preferably have a decomposition start temperature of 100 to 360 ° C, and particularly preferably 100 to 350 ° C. If the decomposition start temperature exceeds 360 ° C., pit formation at the time of recording is not performed well, and jitter characteristics deteriorate. Further, if the temperature is lower than 100 ° C., the storage stability of the disk deteriorates.

For the purpose of improving optical characteristics, recording sensitivity, signal characteristics, etc., the above dyes may be mixed with other organic dyes, metals, metal compounds, or a layer composed of a dye layer and other organic dyes, metals, metal compounds. May be laminated. Examples of such metals and metal compounds include In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO ₂ , SnO, As, Cd, and the like. It can be used by laminating.
Furthermore, various materials such as ionomer resin, polyamide resin, vinyl resin, natural polymer, silicone, liquid rubber, or a silane coupling agent may be dispersed and mixed in the dye, For the purpose of improving the properties, stabilizers (for example, transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers and the like can be used together.

The recording layer can be formed by ordinary means such as vapor deposition, sputtering, CVD, and solvent coating.
When the coating method is used, the above-described dye or the like can be dissolved in an organic solvent, and the coating can be performed by a conventional coating method such as spraying, roller coating, dipping, or spin coating. Organic solvents generally used include alcohols such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; sulfoxides such as dimethyl sulfoxide Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene; cellosolves such as methoxyethanol and ethoxyethanol; hexane and penta , Cyclohexane, and hydrocarbons such as methylcyclohexane.

  A preferable dye film thickness is 4 to 100 nm. This is because if the dye film thickness is thinner than this range, it is difficult to obtain the degree of signal modulation (contrast). On the contrary, if the dye film thickness is thick, the mark shapes are difficult to align and jitter is likely to increase.

[Reflective layer]
As the reflective layer material, a substance having a high reflectance with respect to the laser beam wavelength is preferable. Examples thereof include Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, and Ta. And at least one metal selected from W, Si, Zn, and In and metalloids. Among them, one of Au, Ag, and Cu is the main component, and Au, Ag, Cu, Al, Ti, V, Cr, Ni, Nd, Mg, Pd, Zr, Pt, Ta, W, Si, Zn, In An alloy to which 0.1 to 10% by weight of at least one selected from the above is added is preferable, and In is particularly preferable (since it is an alloy, naturally, combinations of Au and Au, Ag and Ag, and Cu and Cu are excluded). By adding 0.1% by weight or more, the crystal grains become fine and a thin film having excellent corrosion resistance is obtained. However, adding more than 10% by weight is not preferable because the reflectance decreases. The base material is most preferably Ag having a high sputter rate, and the additive is particularly preferably Au, Cu, Mg, or In having a small refractive index n and a large absorption coefficient k.

Ag has the smallest n among all the elements and the highest light utilization efficiency. Therefore, in order not to impair the characteristics, it is particularly preferable that the total amount of additives is 5% by weight or less.
Further, when an auxiliary layer similar to the above is laminated on the first reflective layer made of an alloy mainly composed of any one of Au, Ag, and Cu, the reflective layer made of the alloy is first formed by sputtering. Subsequently, an auxiliary layer may be laminated in the same manner as described above.
A preferable thickness of the reflective layer is 5 to 500 nm, particularly preferably 10 to 300 nm. If it is thinner than 5 nm, sufficient wobble characteristics cannot be obtained, and if it is thicker than 500 nm, jitter characteristics deteriorate.

[Transparent intermediate layer]
The transparent intermediate layer is preferably used as an adhesive layer, and as the material thereof, an existing acrylate-based, epoxy-based, urethane-based ultraviolet curable adhesive or thermosetting adhesive can be used. Furthermore, the method of bonding with a transparent sheet may be used. The film thickness is preferably in the range of 45 to 70 μm. Outside this range, it becomes difficult to reproduce the signal of each information recording layer by narrowing the laser beam, which is the reproduction light, so as to be focused on the first or second information recording layer and detecting the reflected light.

  Examples of the optical recording medium according to the present invention and comparative examples will be described in detail below with reference to the drawings. In each embodiment, the present invention is applied to the optical recording medium having the DVD-R configuration described with reference to FIG.

<Examples 1 to 7, Comparative Example 1>
The in-plane (R = 24 mm, 40 mm, 58 mm) land pre-pit shape and groove shape at the time of manufacturing the stamper are shown in Table 1 below. Both the land pre-pit shape and the groove shape were evaluated at the time of stamper production using an atomic force microscope (AFM, manufactured by Nanotechnology). In Table 1, for example, Examples 1 to 4 satisfy all the numerical value limiting conditions defined as described above .

  Using the stamper, injection molding was performed using PC (polycarbonate) as a substrate material. The land pre-pit shape and groove shape of the substrate produced at this time were also evaluated during the stamper production (see Table 1 above). A dye recording layer was formed on the produced substrate, and a reflective layer made of Ag and a protective layer made of an ultraviolet curable resin were further formed thereon to constitute an optical recording medium. The width of the wobble groove was 320 nm and the track pitch was 740 nm.

  On this substrate, a squarylium dye of the following chemical formula (1) and a formazan chelate dye of the following chemical formula (2) are mixed at a ratio of 7: 3 and dissolved in 2,2,3,3-tetrafluoropropanol. The liquid was spin coated to form a first recording layer having a thickness of 50 nm (500 mm). Next, a reflective layer made of Ag having a thickness of 100 nm (1000 mm) was formed on the first recording layer by sputtering using Ar as a sputtering gas. Further, an ultraviolet curable resin was applied onto the reflective layer by a spin coating method, and the ultraviolet curable resin was irradiated with ultraviolet rays to be cured, thereby forming a protective layer having a thickness of 10 μm. Subsequently, the substrate and the cover plate (PC) were bonded together with an ultraviolet curable adhesive (manufactured by Nippon Kayaku Co., Ltd., KARAYAD DVD576) to produce a DVD-R type optical recording medium shown in FIG.

  Next, for each of the optical recording media in Examples 1 to 7 and Comparative Example 1 described above, the DVD-R-compatible evaluation apparatus, that is, the reproduction light wavelength λ is 650 nm, and the numerical aperture NA of the objective lens is 0.60. Using an evaluation apparatus of ± 0.05, jitter (%), PI error, BLER (%), AR characteristics, and LPPb (degree of modulation) were measured. As for the evaluation condition, a DVD (8-16) signal was recorded under the condition of 6 × speed (20.94 m / s). As a recording condition, a pulse emission pattern according to the DVD-R standard was adopted.

  The results are shown in Table 2 below. For example, in DVD-R, standards are selected so that jitter is less than 8%, PI error is less than 280, BLER is less than 5%, and AR characteristics are 15 or more. Therefore, from the results of Table 2 below, it is clear that the optical recording medium of the configuration of the present invention in each of the above-described embodiments exhibits good error characteristics and reproduction characteristics within the standard.

It is a schematic diagram which shows roughly a specific example of the land prepit formed in the optical recording medium. It is a schematic diagram which shows roughly the other specific example of the land prepit formed in the optical recording medium. It is a schematic diagram which shows roughly the further another specific example of the land prepit formed in the optical recording medium. It is sectional drawing which shows the manufacturing process of a stamper in order. It is a block diagram (block diagram of an optical recording device) showing a configuration of an optical disc cutting device for producing an optical disc master. 1 is a schematic perspective view showing a part of an optical disc master according to the present invention. It is sectional drawing which shows the layer structure of the optical recording medium based on this invention.

Explanation of symbols

1: Substrate 2: Recording layer 3: Reflective layer 4: Protective layer 5: Adhesive layer 6: Cover layer 11: Land 12: Groove track 13: Trace of beam spot
(Groove center line)
20: Land pre-pit (LPP)
61: Substrate 62: Photosensitive layer 63a: Groove pattern 63b: Land pre-pit pattern 64: Stamper (master stamper)
64a: plating layer 65: mother stamper 66: sun stamper 66a: groove pattern 66b: land prepit pattern La: light beam 206: recording master 206a: glass disk 206b: photoresist layer La: light beam Aw: size of land prepit (Length in the direction perpendicular to the track direction)
Lw: Land pre-pit size (length in the track direction)
Aw (in): Aw dimension on the inner circumference side Aw (out): Aw dimension on the outer circumference side W (G): Groove width W (LPP): LPP width

Claims (1)

A stamper for manufacturing an optical recording medium having a substrate on which wobble grooves and land pre-pits are formed, wherein at least the wobble grooves and land pre-pits are formed on a surface thereof, and the land pre-pits are formed on the wobble grooves. The length Lw becomes longer from the inner periphery to the outer periphery when the length of the land prepit in the direction along the wobble groove is Lw. A substrate injection-molded using a stamper,
A recording layer provided on the substrate and containing a squarylium dye represented by the following chemical formula (1) and a formazan chelate dye represented by the following chemical formula (2) in a mixing ratio of 7: 3 ;
In the land prepit formed in the stamper, the length in the direction along the wobble groove in the inner peripheral portion (R = 24 mm) is Lw_in, and the length in the direction along the wobble groove in the outer peripheral portion (R = 58 mm) is set. When the length is Lw_out, the ratio of Lw_out to Lw_in: Lw_out / Lw_in is 1.10 or more and 1.30 or less, and (Lw_out + Lw_in) / 2 is 850 nm or more and 1150 nm or less,
The substrate injection-molded using the stamper has a length in the direction along the wobble groove in the inner peripheral portion (R = 24 mm) in the land prepit as Lw_in, and the wobble in the outer peripheral portion (R = 58 mm). When the length along the groove is Lw_out, the ratio of Lw_out to Lw_in: Lw_out / Lw_in is 1.00 or more and 1.10 or less, and (Lw_out + Lw_in) / 2 is 700 nm or more and 1150 nm or less. optical recording medium, characterized in that.

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