JP2009266299A - Optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk which enables a stable recording layer to be formed and obtains a satisfactory BCA (Burst Cutting Area) amplitude even when an auxiliary information recording region is formed in a mirror surface. <P>SOLUTION: The optical disk includes a disk like substrate having a spiral groove formed on one surface thereof and a reflection layer and a recording layer formed on the one surface of the substrate. In the optical disk, a region in which the reflection layer and the recording layer are formed has a main information recording region in which user information is recorded and the auxiliary information recording region in which auxiliary information is recorded in a bar code shape, the auxiliary information recording region is formed on the inner peripheral side of the main information recording region and has the mirror surface in which no guide groove is formed, wherein in the innermost peripheral side of the auxiliary information recording region, the guide groove is formed or the mirror surface of the auxiliary information recording region is formed to be lower than the substrate surface between guide grooves of the main information recording region. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical disc, and more specifically to an optical disc having an auxiliary information recording area in which auxiliary information is recorded in a bar code form in addition to a main information area in which user information is recorded.

  Conventionally, in an optical disc, management information such as a serial number and a lot number is converted into a barcode and recorded on the optical disc, which is used as a method for identifying whether the disc is a legitimate manufacturer or seller's optical disc. Yes. More specifically, a bar code mark (hereinafter referred to as “BCA mark”) is recorded in a burst cutting area provided on the innermost periphery of the optical disc, and the optical disc is reproduced by a drive. The BCA mark is read by the provided optical head.

  Currently, high-density discs such as CD to DVD, HD DVD, and Blu-ray disc are being developed as optical discs, while optical disc drives, players, and recorders are required to be compatible with these discs. However, it is necessary to identify these optical disks, and one method is to provide information unique to the disks as BCA marks. In addition, unauthorized copying of information is prevented by using a part of the BCA mark, and the BCA mark is an increasingly important and essential item in optical discs.

Each of the barcode-shaped BCA marks on which the auxiliary information is recorded extends widely along the radial direction.
The BCA mark is formed at the manufacturing stage of the optical disc. Specifically, in the case of a DVD-ROM, for example, the reflection film is removed with a YAG laser. In addition, in the case of a write-once optical disc such as a DVD-R, if the reflective film is removed, the light-absorbing dye recording layer and the reflective layer may be peeled off. A method of reproducing by utilizing the difference in optical reflectance by modifying the absorbing dye recording layer is employed.

  On the other hand, the tracking groove provided on the substrate surface of the optical disk extending along the circumferential direction is usually formed using a stamper. In such an optical disk, the main information recording area and the auxiliary information recording area are also formed. (Sometimes referred to as “BCA area”), the auxiliary information recording area is formed with a uniform groove in the same manner as the main information recording area.

However, as described in Patent Document 1, pre-pits and pre-grooves are formed in the auxiliary information recording area at the same track pitch as the main information recording area. In this case, there is a risk that the BCA mark in the BCA area will be erased or tampered with by the recording / reproducing drive. There is a problem that it becomes possible.
In order to solve such a problem, in Patent Document 1, a prepit or pregroove track is provided in a BCA area where a bar-code mark such as a BCA mark is recorded, and the track pitch is set based on actual user data or a disc. It has been proposed to set wider than the track pitch of the read-only area for recording information or the recording / playback area.

  Since the auxiliary information recording area (BCA) of the conventional optical disc D is formed with a relatively deep tracking groove as in the main information recording area, identification information is obtained from the auxiliary information recording area (BCA area). When reading is performed by tracking open, since the interference of light due to the return light from the tracking groove of the laser beam and the land between the tracking grooves is increased and the reflectance is reduced, the reflectance is reduced. The RF signal to be reproduced is affected, specifically, the BCA amplitude decreases, and the identification information recorded in the auxiliary information recording area (BCA) may not be read.

In Patent Document 2, in order to solve this problem, the recording layer on the disk surface is divided into at least a main information recording area and an auxiliary information recording area, a groove is formed in the main information recording area, and recording is performed in the auxiliary information recording area. In an optical disc on which information marks are formed, a groove or a prepit having a depth smaller than that of the groove formed in the main information recording area is formed in the recording layer of the auxiliary information recording area, or the auxiliary It has been proposed not to form grooves or prepits in the recording layer of the information recording area.
JP 2005-518055 Gazette JP 2007-102984 A

As described above, in Patent Document 2, a groove or prepit having a depth smaller than the depth of the groove formed in the main information recording area is formed in the recording layer of the auxiliary information recording area, or the auxiliary information recording area An optical disc according to an embodiment in which grooves or pre-pits are not formed in the recording layer is an embodiment of the superordinate concept.
However, no groove or pre-pit is formed in the recording layer of the auxiliary information recording area, in other words, if a barcode-like BCA mark is formed on the mirror surface where no groove is provided, a stable recording layer cannot be formed, There is a problem that the BCA amplitude cannot be obtained sufficiently.
In addition, the recording layer stacked on the mirror surface changes in film thickness as compared with the main information recording area in which grooves are formed for recording and reproducing user information, so that the recorded barcode information is reproduced. It is difficult to obtain a sufficient BCA amplitude necessary for the above.

  The present invention has been made in view of the circumstances as described above. Even when the auxiliary information recording area is formed on the mirror surface, a stable recording layer can be formed and a sufficient BCA amplitude can be obtained. An object of the present invention is to provide an optical disc that can be used.

  As a result of intensive studies to achieve the above object, the inventor forms a stable recording layer by providing a guide groove on the innermost periphery and forming a mirror surface of the BCA region lower than the substrate surface. It was possible to obtain a sufficient BCA amplitude.

The present invention has been completed based on these findings, and is as follows.
[1] In an optical disc having a disk-shaped substrate having a spiral groove formed on one surface, and a reflective layer and a recording layer formed on the one surface of the substrate,
The area in which the reflective layer and the recording layer are formed has a main information recording area in which user information is recorded and an auxiliary information recording area in which auxiliary information is recorded in a barcode shape,
The auxiliary information recording area has a mirror surface that is formed on the inner peripheral side from the main information recording area and in which no guide groove is formed,
An optical disc, wherein a guide groove is formed on the innermost peripheral side of the auxiliary information recording area.
[2] In an optical disc having a disk-shaped substrate having a spiral groove formed on one surface, and a reflective layer and a recording layer formed on the one surface of the substrate,
The area in which the reflective layer and the recording layer are formed has a main information recording area in which user information is recorded and an auxiliary information recording area in which auxiliary information is recorded in a barcode shape,
The auxiliary information recording area has a mirror surface that is formed on the inner peripheral side from the main information recording area and in which no guide groove is formed,
An optical disc, wherein a mirror surface of the auxiliary information recording area is formed lower than a substrate surface between guide grooves of the main information recording area.

  In the present invention, the loss of BCA amplitude can be reduced by using the auxiliary information recording area as a mirror surface, and a stable recording layer can be formed on the mirror surface portion by providing a guide groove on the innermost periphery. Sufficient BCA amplitude can be obtained. In the present invention, since the BCA area mirror surface is formed lower than the substrate surface, the recording layer in the BCA area can be formed thick, so that a sufficient BCA amplitude can be obtained.

  Hereinafter, the optical disc of the present invention will be described using an embodiment of a Blu-ray disc (BD-R). However, the optical disc of the present invention is not limited to the BD-R of the present embodiment, but a read-only type represented by CD and DVD-ROM, a write-once type represented by CD-R and DVD-R, The present invention can also be applied to an optical disc having a plurality of recording layers such as a rewritable type represented by CD-RW and DVD-RW / RAM, or a write-once type.

FIG. 1 is a plan view showing the entire structure of an optical disc 10 of the present invention, and FIG. 2 is a partially enlarged sectional view for explaining an example of the structure of the main information recording area 2.
As shown in FIG. 1, the optical disk 10 of the present embodiment has a center hole 4, and on one main surface side, an auxiliary information recording area 1 is provided on the inner peripheral side, and main information recording is performed on the outer peripheral side. Region 2 is provided. A BCA mark 3 is formed in the auxiliary information recording area 1.

As shown in FIG. 2, the main information recording area 2 is provided on a disk-shaped substrate 11 having a thickness of about 1.1 mm in which a spiral guide groove 12 is formed on one main surface. A reflective layer 13 for reflecting laser light, a recording layer 14 containing a light-absorbing substance, a protective layer 15, an adhesive layer 16 provided as necessary, and light having a thickness of about 0.1 mm on the main surface. A transparent layer 17 in this order, and the surface of the light reflecting layer 13 opposite to the main surface on which the groove 12 of the substrate 11 is formed corresponds to the groove 12 of the substrate 11. Thus, a groove 13b spirally formed with a track pitch TrB = 0.32 μm equal to the groove 12 of the substrate 11 and a land 13a adjacent to the groove 13b are formed.
By irradiating the main information area 2 with a laser beam having a wavelength of 400 to 420 nm (for example, 405 nm) based on the recorded information, the optically readable main information is recorded on the recording layer 14.

In the present invention, as the substrate 11, various materials used as substrate materials for conventional optical information recording media can be arbitrarily selected and used. Specific examples include acrylic resins such as polycarbonate and polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, metals such as epoxy resins, amorphous polyolefins, polyester resins, and aluminum, and glass. These may be used together if necessary. Among the above materials, a thermoplastic resin is preferable from the viewpoint of moldability, moisture resistance, dimensional stability, and low price, and polycarbonate is particularly preferable.
When these resins are used, it is preferable to form the substrate 11 in a predetermined shape (disk shape in the case of an optical disk) by a method such as injection molding. The thickness of the substrate 11 is preferably in the range of 0.9 to 1.1 mm. Moreover, it is not restricted to this, For example, it can apply | coat on a base using an ultraviolet curable resin, and can also use it, hardening a coating film.

In the present invention, the spiral guide groove 12 is formed in the main information recording area 2 on the outer peripheral side of one main surface of the substrate 11, but in the auxiliary information recording area (BCA area) 1 on the inner peripheral side. Is characterized in that it is not provided.
The irregularities formed by the guide grooves 12 formed in the main information recording area 2 form the grooves 13b and the lands 13a.
The guide groove 12 is a mold plate called a stamper in which a main surface of the mold is used for injection molding of the substrate 11 and a fine pattern of a spiral ridge having a pattern opposite to that of the guide groove 12 is provided on one main surface. Are preferably formed simultaneously with the injection molding of the substrate 11.

FIG. 3 schematically shows an example of the shape of the substrate in the auxiliary information recording area (BCA area) formed on the inner peripheral side of the substrate and the main information recording area 2 formed on the outer peripheral side of the substrate according to the present invention. FIG.
In the example shown in FIG. 3, the auxiliary information recording area 1 has a mirror surface on which no guide groove is formed, and another guide groove 12 ′ is formed on the innermost peripheral side of the auxiliary information recording area 2. ing.
In the present invention, by providing the guide groove 12 'on the innermost circumference, it is possible to solve the problem that a stable recording layer on the mirror surface cannot be formed and sufficient BCA amplitude cannot be obtained.
The shape of the guide groove 12 ′, that is, the pitch and / or the depth may be the same as or different from that of the guide groove 12, and is formed at the same time as the guide groove 12.

  In addition, the mirror surface of the auxiliary information recording area 2 in the example shown in FIG. 3 may be formed the same as the substrate surface between the guide grooves of the main information recording area, as shown in FIG. As shown in B), it may be formed the same as the groove surface of the guide groove in the main information recording area, and may be between the two.

FIG. 4 shows another example of the shape of the substrate in the auxiliary information recording area (BCA area) formed on the inner peripheral side of the substrate and the main information recording area 2 formed on the outer peripheral side of the substrate according to the present invention. FIG.
In the example shown in FIG. 4, the auxiliary information recording area 1 has a mirror surface on which no guide groove is formed, and the mirror surface of the auxiliary information recording area 2 is a substrate surface between the guide grooves of the main information recording area. It is formed lower than.
In the present invention, by forming the mirror surface of the BCA region lower than the substrate surface, the recording layer of the BCA region can be formed thick, so that a sufficient BCA amplitude can be obtained.

The reflective layer 13 in the present invention reflects a laser beam for recording and / or reproducing data, and in order to increase the reflectance with respect to the laser beam or to provide a function for improving the recording / reproducing characteristics, the substrate 11. And the recording layer 14 and is formed on the surface of the substrate 11 where the groove 12 is formed, for example, by vapor deposition, ion plating, sputtering, or the like. Among these, the sputtering method is particularly preferable in terms of mass productivity and cost.
The

The material constituting the reflective layer 13 may be any material preferably used in ordinary Blu-ray discs, such as a metal film such as Au, Al, Ag, Cu or Pd, an alloy film of these metals, or a metal thereof. An alloy film to which a trace component is added is preferably used.
For Ag, for example, Au, Al, Cu, Ti, Cr, Ni, Ta, Pd, Mg, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, In, By containing elements such as Zn, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, and rare earth metals as alloys, high reflectivity, good BCA recording sensitivity, good storage stability Sex etc. are obtained.

  In the present invention, the recording layer 14 preferably contains a light absorbing material composed of an organic dye that absorbs laser light. Among these, a dye-type recording layer in which pits are formed by laser beam irradiation and data is recorded is preferable. The organic dye is preferably a phthalocyanine dye, a cyanine dye, an azo dye, or the like. For example, an azo dye represented by Chemical Formula 1 or a cyanine dye represented by Chemical Formula 2 is combined with a binder or the like in a solvent such as TFP (tetrafluoropropanol). Dissolve to prepare a coating solution, and then apply the coating solution through the reflective layer by a spin coating method, a screen printing method, or the like to form a coating film, and then, for example, dry at a temperature of 80 ° C. for about 30 minutes It is preferable to form by doing.

(Wherein, A and A 'are nitrogen atom, an oxygen atom, a sulfur atom, comprising one or more hetero atoms selected from a selenium atom and a tellurium atom, represent the same or different heterocyclic rings from each other, R ₂₁ to R ₂₄ each independently represents a hydrogen atom or a substituent, and Y ₂₁ and Y ₂₂ each represent the same or different heteroatom selected from the group 16 elements in the periodic table.

(In the formula, Φ ⁺ and φ each represent an idrenin ring residue, a benzoindolenin ring residue or a dibenzoindolenine ring residue, L represents a linking group for forming a mono- or dicarbocyanine dye, X ^- represents an anion, m is an integer of 0 or 1).

  In the present invention, a light absorbing material made of an inorganic material may be used as the recording layer 14. As such an inorganic material, Te—Pd, Si—Cu, Ge—Bi, or the like is used. The inorganic material-based recording layer is formed by depositing these materials by vapor deposition or sputtering.

In the present invention, the protective layer 15 may be formed between the recording layer 14 and a light transmission layer 17 described later for the purpose of adjusting recording characteristics, improving adhesion, protecting the recording layer 14, and the like. preferable.
The protective layer 15 is preferably a transparent film made of SiO ₂ , ZnS—SiO ₂ , Nb ₂ O ₅ —Al ₂ O ₃ , etc. The optical recording is performed by, for example, vapor deposition, ion plating, sputtering, or the like. It is preferably formed on the surface on which the layer 14 is formed. Among these, the sputtering method is particularly preferable in terms of mass productivity and cost.

In the present invention, the adhesive layer 16 is an arbitrary layer formed in order to improve the adhesion between the protective layer 15 and the sheet-like transparent layer 17 described below.
Such an adhesive layer 16 is preferably an epoxy-based or other transparent reactive curable resin or an ultraviolet curable transparent resin as a main component, and is preferably formed by means such as a spin coating method or a screen printing method. After coating on the protective layer 15 and / or the lower surface of a sheet-like light transmitting layer 17 having a thickness of about 0.1 mm, which will be described later, the protective layer 15 of the substrate 11 and the sheet-like light transmitting layer 17 are bonded to each other. An optical disk having a thickness of about 1.2 mm is obtained which is joined by the layer 16.

In the present invention, the light transmission layer 17 is preferably made of a transparent resin. More specifically, for example, it is preferable to use a sheet made of a resin having good light transmission properties such as polycarbonate resin and acrylic resin, or to form a light transmission layer by applying these resins.
The thickness of the light transmission layer 17 is usually configured so that laser light having a wavelength in the vicinity of 400 nm to 420 nm is irradiated and data recording to the optical recording layer 14 and / or reading from the optical recording layer 14 is performed. Usually, it is preferably 0.1 mm.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
<Manufacture of substrates>
A photoresist (photosensitive agent) is applied on a glass master by a spin coating method to a predetermined thickness to form a resist film, and is exposed to a predetermined exposure width by a laser beam of a cutting device, and then obtained. A developing solution was dropped on the glass master disc and developed to form an uneven resist pattern corresponding to the groove of the substrate shown in FIG.
Next, nickel was deposited on the glass master by plating, and this was peeled off, and the outer shape was trimmed into a disk shape to obtain a stamper.
Next, this stamper is set in the cavity of the injection molding apparatus, polycarbonate resin is injected into the cavity, and a spiral guide groove on the outer peripheral side as shown in FIG. And a substrate having a guide groove 12 ′ at the innermost periphery is obtained, and this is used as the substrate of Example 1.
Further, in the same manner as in the first embodiment by changing the stamper, a substrate having an auxiliary information recording area lower than the substrate surface between the guide grooves of the main information recording area as shown in FIG. The substrate of Example 2 was formed.

<Formation of light reflecting layer, recording layer, protective layer and light transmitting layer>
A light reflecting layer was formed on the main surface of the substrate of Example 1 on which the spiral groove was formed, using a sputtering apparatus and using an Ag alloy as a target material.
Next, a dye solution containing an azo organic dye represented by Chemical Formula 1 was applied onto the substrate by a spin coating method to form a recording layer.
Further, a protective film was formed on this substrate by sputtering ZnS—SiO ₂ using a sputtering apparatus.
Finally, after applying an ultraviolet curable adhesive mainly composed of acrylic resin on this substrate, a 0.1 mm thick polycarbonate resin disk-shaped sheet is bonded to this substrate and irradiated with ultraviolet rays. Then, the adhesive was cured to form a light transmission layer, and an optical disk of Example 1 having a thickness of about 1.2 mm was obtained.
A light reflection layer, a recording layer, a protective layer, and a light transmission layer were formed on the substrate of Example 2 by the same process, and an optical disk of Example 2 having a thickness of about 1.2 mm was obtained.

<Formation of BCA mark>
Next, a BCA cutting apparatus having a laser wavelength of 810 nm and a beam diameter of about 0.85 μm × about 35 μm in the region corresponding to the BCA of the optical discs of Example 1 and Example 2, a laser bias power of 100 mW, a cutting speed of 1000 rpm, A BCA mark 4 having a circumferential width of 10 μm was formed under the conditions of a radial beam feed amount of 6 μm, a recording start position of 21.0 mm, and a recording end position of 22.0 mm.

(Comparative example)
In Example 1, an optical disk was obtained in the same manner as in Example 1 except that the same guide groove 12 was formed in the auxiliary information recording area 2 and the main information recording area 1 on the substrate.

Using the optical disks obtained in Example 1, Example 2 and Comparative Example, the BCA amplitude of the formed BCA mark was measured.
FIG. 5 is a photograph showing the results. The left side is a comparative example having a guide groove in the auxiliary information recording area, and the right side is a mirror surface without the guide groove in the auxiliary information recording area. Example 1.
The amplitude of BCA was 387 mV in the comparative example with the guide groove, but in Example 1 with a mirror surface, it was 514 mV, and about 30% of the loss due to interference could be recovered. In Example 2, the voltage was 438 mV, and a loss of about 13% due to interference could be recovered.

The top view which shows the whole optical disk structure of this invention. The partial expanded sectional view which shows the groove | channel 12 of the optical disk of this invention. The figure which shows typically the example of the shape of the substrate surface in the radial direction on a board | substrate. The figure which shows typically the other example of the shape of the board | substrate surface in the radial direction on a board | substrate. The photograph which shows the result of having measured the BCA amplitude of the formed BCA mark using the optical disk obtained by the Example and the comparative example.

Explanation of symbols

1: Auxiliary information recording area (BCA)
2: Main information area 3: BCA mark 4: Center hole 10: Optical disc 11: Substrate 12, 12 ': Guide groove 13: Reflective layer 13a: Land 13b: Groove 14: Recording layer 15: Protective layer 16: Adhesive layer 17 : Light transmission layer

Claims (2)

In an optical disc having a disk-shaped substrate having a spiral groove formed on one surface, and a reflective layer and a recording layer formed on the one surface of the substrate,
The area in which the reflective layer and the recording layer are formed has a main information recording area in which user information is recorded and an auxiliary information recording area in which auxiliary information is recorded in a barcode shape,
The auxiliary information recording area has a mirror surface that is formed on the inner peripheral side from the main information recording area and in which no guide groove is formed,
An optical disc, wherein a guide groove is formed on the innermost peripheral side of the auxiliary information recording area. In an optical disc having a disk-shaped substrate having a spiral groove formed on one surface, and a reflective layer and a recording layer formed on the one surface of the substrate,
The area in which the reflective layer and the recording layer are formed has a main information recording area in which user information is recorded and an auxiliary information recording area in which auxiliary information is recorded in a barcode shape,
The auxiliary information recording area has a mirror surface that is formed on the inner peripheral side from the main information recording area and in which no guide groove is formed,
An optical disc, wherein a mirror surface of the auxiliary information recording area is formed lower than a substrate surface between guide grooves of the main information recording area.