JP2007294055A - Optical information recording medium and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium which recognizes barcode information recorded in a two optical absorption layers in a short time and reproduces the barcode information with high signal quality. <P>SOLUTION: In the optical information recording medium 12 in which film thickness of the first optical absorption layer closer to the light incidence side is smaller than film thickness of the second optical absorption layer far from the light incidence side and which has a transparent intermediate layer 19 whose film thickness is 40 μm or less, irradiation with blue laser is performed from the first optical absorption layer side through a first transparent substrate 13, a BCA with the same barcode information recorded therein is formed at the same radial position with the first layer and the second layer and the barcode information with the excellent signal quality is reproduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical information recording medium or the like, and more particularly to an optical information recording medium or the like in which management information is recorded in bar code in addition to user information.

Conventionally, on the innermost circumference of an optical information recording medium such as a DVD-ROM, a burst cutting area (hereinafter referred to as “burst cutting area”) in which bar code information is recorded as an area for reading information without performing tracking servo control. BCA "may be written). In the BCA, management information such as a serial number is recorded as identification information for each optical information recording medium and used for copyright protection (see Patent Documents 1 to 3).
In addition, in order to manage user information (for example, programs, data, application information, etc.) recorded in the user information area or to protect the copyright, the system lead-in outside the user information area of the optical information recording medium is used by the user. A management information is recorded by the same modulation system as the information area, while a management information is recorded in the BCA by a modulation system different from the user information area (see Patent Document 4).
Such BCA is formed at the manufacturing stage of the optical information recording medium. Specifically, in the case of a DVD-ROM, for example, the reflection film is removed with a YAG laser (see Patent Document 5). On the other hand, in the case of a write-once optical information recording medium DVD-R, the recording layer and the reflective film may be peeled off if the reflective film is removed with a YAG laser like a DVD-ROM. A BCA is formed by recording a barcode in a groove portion in the region.

JP 2000-149423 A JP 2000-222783 A JP 2001-043533 A JP-A-10-188361 Japanese Patent Laid-Open No. 06-203212

Incidentally, in recent years, a two-layer type optical information recording medium having two recording layers has been developed in response to an increase in information capacity. Among these, write-once optical information recording media using a dye material that absorbs laser light are used for many purposes because they cannot be rewritten. In these two-layer discs, BCA is formed on one layer. For example, in a dual-layer DVD-R, BCA is formed in the first light absorption layer in front.
When an optical information recording medium is mounted on a recording / reproducing apparatus to read BCA management information, the recording / reproducing apparatus focuses on one layer and then moves the optical head to the radius where the BCA is formed, thereby managing the BCA. Read information. However, if there is no BCA in the first focused layer, the other layer is focused and the BCA is searched. In such a case, there is a problem that it takes time to access the recording / reproducing apparatus.

The present invention has been made to solve the above-described problems.
That is, an object of the present invention is to provide an optical information recording medium having a BCA capable of shortening the access time from a recording / reproducing apparatus in an optical information recording medium having two light absorbing layers containing a light absorbing material capable of recording / reproducing. There is to do.
Another object of the present invention is to provide an optical information recording medium having two light absorbing layers containing a light absorbing material, and a method for producing an optical information recording medium having BCA with excellent signal quality in both layers. There is to do.

  Therefore, as a result of intensive studies to solve the problems of the preceding paragraph, the present inventors have developed a recordable / reproducible light-absorbing material in which user information is optically recorded along a concentric or spiral track by irradiation with a blue laser from one side. An optical information recording medium having a BCA having two recording layers and having BCA in which management information is recorded as bar code information inside concentric or spiral tracks is completed. It came to do.

That is, firstly, the optical information recording medium to which the present invention is applied includes BCA in the first layer on the near side when viewed from the light incident side, and the first layer is at the same radial position as the first layer BCA. A second-layer BCA in which the same management information as the BCA of the eye is recorded is formed.
Second, the optical information recording medium to which the present invention is applied includes the BCA recording start position (BCA2S) provided in the second light absorption layer and the BCA provided in the first light absorption layer. The recording start position (BCA1S) is
ΔS = BCA2S−BCA1S ≦ 15 μm
Satisfy the relationship.
Third, in the optical information recording medium to which the present invention is applied, the signal amplitude obtained from the BCA provided in the first light absorption layer is obtained from the BCA provided in the second light absorption layer. It is smaller than the signal amplitude.
Fourthly, in the optical information recording medium to which the present invention is applied, the first light absorption layer on the near side as viewed from the light incident side has a low reflectivity of recorded marks higher than the reflectivity before recording. to High recording.
Fifth, as a method of forming BCA on the optical information recording medium to which the present invention is applied, the optical information recording medium is irradiated with laser light from the direction in which user information is recorded, Bar code information is simultaneously recorded on the second light absorption layer.

  Thus, according to the present invention, an optical information recording medium provided with two light-absorbing layers having an information area in which user information can be recorded and reproduced along a concentric or spiral track by the blue laser light irradiated from one side. A burst cutting area (first layer) provided inside the user information area of the first light absorption layer on the near side as viewed from the light incident side and recording predetermined management information as barcode information ( BCA) and the first layer burst cutting area (BCA) at the same radial position as the first layer burst cutting area (BCA). And a second layer burst cutting area (BCA) in which the same management information as the management information recorded in (2) is recorded is provided. That.

Here, in the optical information recording medium to which the present invention is applied, the recording start position (BCA2S) at the center of the width of the burst cutting area (BCA) of the second layer and the burst cutting area (BCA) of the first layer are arranged. It is preferable that the recording start position (BCA1S) at the center of the width satisfies the relationship of the following formula (1).
ΔS = (BCA2S) − (BCA1S) ≦ 15 μm Formula (1)
(However, in equation (1), ΔS is the difference (unit: μm) between (BCA2S) and (BCA1S).)

In the optical information recording medium to which the present invention is applied, the signal amplitude obtained from the first layer burst cutting area (BCA) is smaller than the signal amplitude obtained from the second layer burst cutting area (BCA). It has characteristics.
And the 1st light absorption layer and the 2nd light absorption layer contain an organic pigment, and the film thickness of the 2nd light absorption layer is thicker than the film thickness of the 1st light absorption layer. It is preferable.

In addition, the optical information recording medium to which the present invention is applied has the first layer burst cutting area (BCA) formed with the reflectance of the first layer burst cutting area (BCA) before the management information is recorded. The second layer burst cutting area (BCA) before the management information is recorded, and the reflectivity of the second layer burst cutting area (BCA) is higher than the reflectance of the region to be recorded. This is characterized by low to high recording which is higher than the reflectance of the region where the image is formed.
Furthermore, the optical information recording medium to which the present invention is applied preferably has a transparent intermediate layer having a thickness of 40 μm or less between the first light absorption layer and the second light absorption layer.

  Next, according to the present invention, there is provided an optical information recording medium having two light absorption layers containing an organic dye, the first light provided on the near side as viewed from the incident side of the light irradiated from one side. An absorption layer, a second light absorption layer provided on the back side when viewed from the light incident side and having a thickness (D2) greater than the thickness (D1) of the first light absorption layer; A transparent intermediate layer having a thickness of 40 μm or less provided between the second light absorption layer and the second light absorption layer, and recording predetermined management information at least in the second light absorption layer There is provided an optical information recording medium characterized by having a burst cutting area (BCA).

Here, the film thickness (D2) of the second light absorption layer is preferably thicker than the film thickness (D1) of the first light absorption layer, and specifically, it is 10% or more thicker. is necessary.
Moreover, it is preferable that the reflectance of the burst cutting area (BCA) is Low to High recording that is higher than the reflectance of the region forming the burst cutting area (BCA) before the predetermined management information is recorded.
Furthermore, the same management information as the management information recorded in the burst cutting area (BCA) at the same radial position as the burst cutting area (BCA) formed in the second light absorption layer of the first light absorption layer. It is preferable to have another burst cutting area (BCA) in which information is recorded.

On the other hand, if the present invention is grasped from the category of the manufacturing method, it is a method for manufacturing an optical information recording medium having two light absorption layers containing an organic dye that can be recorded and reproduced by light, and is provided on the light incident side on the transparent substrate. Through the first light-absorbing layer on the near side when viewed from the side, the first light-absorbing layer and the transparent intermediate layer having a thickness of 40 μm or less, the second A light absorption layer is formed, a blue laser is irradiated from the light incident side through the transparent substrate, and predetermined management information is simultaneously barcoded on the first light absorption layer and the second light absorption layer. There is provided a method for manufacturing an optical information recording medium, characterized by forming a burst cutting area (BCA) recorded as information.
In this case, the ratio (D2 / D1) of the film thickness (D2) of the second light absorption layer to the film thickness (D1) of the first light absorption layer is 1.1 or more (D2 / D1 ≧ 1.1). ) Is preferable.

  According to the present invention, barcode information recorded on an optical information recording medium having two light absorption layers can be recognized in a short time, and barcode information with high signal quality can be reproduced.

The best mode for carrying out the present invention (hereinafter, an embodiment of the present invention) will be described in detail below. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. The drawings used are for explaining the present embodiment and do not represent the actual size.
The optical information recording medium to which this embodiment is applied includes a first layer provided on the front side and a second layer provided on the back side when viewed from the incident side of light irradiated from one side.

FIG. 1 is a diagram for explaining an optical information recording medium to which the present embodiment is applied. FIG. 1A is a diagram illustrating each region of the first layer of the optical information recording medium, and FIG. 1B is a diagram illustrating each region of the second layer of the optical information recording medium.
As shown in FIG. 1A, the first layer of the optical information recording medium 1 is provided with a central hole in a disc-shaped central portion. Around the center hole, there is a flat first layer mirror region 2 in which no groove or pit is formed. On the outer peripheral side of the mirror area 2 of the first layer, information of the first layer that records predetermined user information along a concentric or spiral track and the BCA 3 of the first layer in which management information is recorded with a barcode. A region 5 is provided.
If necessary, the first-layer mirror region 4 and the first-layer mirror are provided between the first-layer BCA 3 and the first-layer information region 5 and outside the first-layer information region 5. Each region 6 is provided.
A pit indicating management information or the like may be formed inside the information area 5 of the first layer. Further, the shape of the first layer BCA 3 in which the management information is recorded with the barcode may be a mirror, or a groove or a pit may be formed.

Next, as shown in FIG. 1B, the second layer of the optical information recording medium 1 is a flat second layer in which no groove or pit is formed around the center hole, like the first layer. It has a mirror area 7. On the outer peripheral side of the mirror area 7 of the second layer, the BCA 8 of the second layer in which management information is recorded by a barcode, and information of the second layer for recording predetermined user information along a concentric or spiral track A region 10 is provided.
If necessary, a second-layer mirror region 9 and a second-layer mirror are provided between the second-layer BCA 3 and the second-layer information region 10 and outside the second-layer information region 10. Each region 11 is provided.
A pit indicating management information or the like may be formed inside the information area 10 of the second layer. The shape of the BCA 8 of the second layer in which management information is recorded with a barcode may be a mirror, or a groove or a pit may be formed.

Next, FIG. 2 is a diagram illustrating a cross-sectional configuration of an optical information recording medium to which the present embodiment is applied. As shown in FIG. 2, in the optical information recording medium 12, the first layer (L 0) on the near side when viewed from the light incident side is formed on the light-transmissive first transparent substrate 13 and the first transparent substrate 13. And the first light absorption layer.
The first light absorption layer is provided on the inner peripheral side of the information area 17 (user information area) of the first layer for recording predetermined user information and the information area 17 of the first layer. And the like, and a first-layer mirror region 14 on the inner peripheral side further than the first-layer BCA 15.
If necessary, a first-layer mirror region 16 provided between the first-layer BCA 15 and the first-layer information region 17 and on the outer peripheral side of the first-layer information region 17, and And one layer of mirror region 18.

Next, the second layer (L1) on the back side when viewed from the light incident side is formed on the second transparent substrate 25 and the second transparent substrate 25 in the same manner as the first layer (L0). The second light absorption layer is thicker than the first light absorption layer of one layer (L0).
The second light absorption layer includes a second layer information area 23 (user information area) for recording predetermined user information, and a BCA15 having a radial position on the inner circumference side of the second layer information area 23 and having a first radial position. And a second-layer BCA 21 in which management information and the like are recorded by a bar code, and a second-layer mirror region 20 further on the inner peripheral side than the second-layer BCA 21.
If necessary, a second-layer mirror region 22 provided between the second-layer BCA 21 and the second-layer information region 23 and on the outer peripheral side of the second-layer information region 23, and And two mirror regions 24.
Then, the first layer (L0) and the second layer (L1) are bonded and integrated with each other through a transparent intermediate layer 19 having a film thickness of 40 μm or less with a transparent adhesive or the like.

In the optical information recording medium 12 to which the present embodiment is applied, it is desirable that the BCA 21 of the second layer is formed at substantially the same radial position as the BCA 15 of the first layer in the first light absorption layer.
Here, “the BCA 21 of the second layer and the BCA 15 of the first layer are formed at substantially the same radial position” means that the recording start position (BCA 2S) of the BCA 21 of the second layer and the recording of the BCA 15 of the first layer It means that the start position (BCA1S) satisfies the relationship of the following formula (1).
ΔS = (BCA2S) − (BCA1S) ≦ 15 μm Formula (1)
In the equation (1), ΔS is the recording start position (BCA2S) at the center of the width of the BCA 21 of the second layer provided concentrically on the second light absorption layer, and the first light absorption layer. The difference (unit: μm) from the recording start position (BCA1S) at the center of the width of the BCA 15 of the first layer provided concentrically.

Further, in the optical information recording medium 12 to which the present embodiment is applied, the first layer burst cutting area (BCA) is added to the second layer burst cutting area (BCA) provided in the second light absorption layer. The management information identical to the management information recorded in (1) is recorded.
Since the same management information is recorded in the first layer burst cutting area (BCA) and the second layer burst cutting area (BCA), the bar code information recorded on the optical information recording medium 12 can be stored in a short time. Further, it is possible to reproduce bar code information with high signal quality.

Next, a cross-sectional structure of the BCA provided in the optical information recording medium to which this embodiment is applied will be described.
First, various methods for preparing an optical information recording medium having two light absorption layers have been proposed. For example, there is a so-called reverse lamination method in which a first light absorption layer and a second light absorption layer are formed on each transparent substrate, and then these transparent substrates are bonded with a transparent adhesive. .
In addition, a first light absorption layer is prepared on a transparent substrate, a transparent resin is applied thereon, a mold is pressed, the transparent resin is cured, and a second layer transparent substrate is produced. 2P method in which the second light absorption layer is stacked.

FIG. 3 is a diagram for explaining a cross-sectional structure of a region (BCA region) where a BCA is formed in an optical information recording medium to which the present embodiment is applied. Here, the optical information recording medium 26 prepared by the reverse lamination method is taken as an example.
As shown in FIG. 3, the BCA region of the optical information recording medium 26 has a first transparent substrate 27 made of a light-transmitting material as a first layer on the near side as viewed from the light incident side, and on the first transparent substrate 27. The first light absorption layer 28 containing the light absorption material formed on the first light absorption layer 28 and the translucent reflection layer 29 formed on the first light absorption layer 28 are included.
The second layer including the second transparent substrate 34, the reflective layer 33 provided in order on the light incident side on the second transparent substrate 34, and the light absorbing material as the second layer on the back side when viewed from the light incident side. The light absorption layer 32 and the interface layer 31 are provided.

The first layer and the second layer are bonded and integrated by the transparent intermediate layer 30 so that the first translucent reflective layer 29 and the second interface layer 31 face each other. Here, the BCA of the first layer is formed in the first light absorption layer 28 and the BCA of the second layer is formed in the second light absorption layer 32, respectively.
In this example, the transparent substrate at the portion where the BCA on which the barcode information is recorded is formed in a mirror shape. However, the shape is not necessarily limited to the mirror shape, and may be a shape including a groove or a pit, for example.

Next, each layer constituting the optical information recording medium 26 will be described.
(First transparent substrate, second transparent substrate)
The material of the first transparent substrate 27 and the second transparent substrate 34 is, for example, a highly transparent material having a refractive index with respect to laser light in the range of 1.4 to 1.7, and a resin excellent in impact resistance is desirable. Specific examples include polycarbonate, amorphous polyolefin, and acrylic, but are not limited thereto.
Incidentally, the first transparent substrate 27 between the first-th light-absorbing layer 28, if _necessary, may be provided an enhanced layer and solvent layer of SiO 2, etc. ZnS-SiO _2.

  The first transparent substrate 27 and the second transparent substrate 34 are preferably prepared by producing a master and a stamper and injection molding. Here, the master is produced as follows, for example. That is, a glass master having a diameter of 200 mm and a thickness of 6 mm is prepared, and a photoresist is uniformly applied on one surface of the glass master using a spin coating method. The thickness of the photoresist is adjusted according to the depth of the pits or grooves. Next, the glass master disc coated with the photoresist is mounted on a cutting device.

  Note that the recording optical head of the cutting apparatus for producing the master is driven by a servo system that moves in the radial direction relative to the master. The recording radius position is monitored with a linear scale and controlled with a closed servo loop. Information data, management information, groove signals, etc. are generated from the formatter to drive the optical head. The entire system is managed by a controller, and servo control of the track pitch is also performed. In this servo control, the track pitch is controlled. The master is rotated by a spindle to form a unique servo loop. The spindle is driven by a spindle driver.

  According to the information sent from the formatter, the cutting apparatus irradiates the photoresist with laser light from the optical head and exposes it to form concentric or spiral pits or grooves. Adjust the laser light quantity to control the pit size and groove width. The glass master disc that has been cut is subjected to electroless plating as a pretreatment for plating on the pattern forming surface. Further, an Ni layer is formed by electroforming using the plated layer as a conductive film. Next, the stamper is obtained by polishing the surface of the Ni layer formed on the glass master and further peeling the Ni layer from the glass master. In addition, you may perform the electrically conductive film formation in the pre-processing of the said plating using a sputtering method or a vapor deposition method.

(First light absorption layer, second light absorption layer)
The material of the first light absorption layer 28 and the second light absorption layer 32 is preferably a light-absorbing organic dye. Specific examples include cyanine dyes, polymethine dyes, triarylmethane dyes, pyrylium dyes, phenanthrene dyes, azo dyes, tetradehydrocholine dyes, triarylamine dyes, squarylium dyes, croconic methine dyes, and the like. It is not limited to these.
These organic dyes may be used singly or as a mixture of two or more organic dyes. Further, it may contain a quencher, other coloring matter, an additive, a polymer (for example, a thermoplastic resin such as nitrocellulose, a thermoplastic elastomer), metal fine particles, or the like.

  In the optical information recording medium 26 to which the present exemplary embodiment is applied, the first light absorption layer 28 of the first layer and the second light absorption layer 32 of the second layer have reflectance after recording information. Is preferably Low to High polarity, which is higher than the reflectance before recording. In this case, among the organic dyes described above, an organic dye having a large absorption at the wavelength of the recording / reproducing light, that is, an organic dye having a large extinction coefficient k of the optical constant is desirable.

The first light absorption layer 28 and the second light absorption layer 32 may be formed by using the above-described organic dyes and optional additives in known organic solvents (for example, tetrafluoropropanol, ketone alcohol, acetylacetone, methylcellulose, toluene, etc. In the case of the first light-absorbing layer 28, the first light-absorbing layer 28 is directly coated on the first transparent substrate 27, and in the case of the second light-absorbing layer 32, the second transparent substrate 34 is dissolved and solvated. Each is applied on the reflective layer 33 formed above.
As a coating method, a spin coating method is usually employed. The spin coating conditions may be performed by combining several rotation speeds from 300 rpm to 5000 rpm from the inner periphery to the outer periphery, and the spin coating conditions, the concentration of the organic dye solution, the viscosity, and the solvent drying speed are adjusted. Thus, the film thicknesses of the first light absorption layer 28 and the second light absorption layer 32 can be controlled.

In the optical information recording medium 26 to which the present embodiment is applied, the film thicknesses of the first light absorption layer 28 and the second light absorption layer 32 are usually 20 nm to 100 nm, preferably 30 nm to 30 nm, respectively. It is prepared in the range of 60 nm.
Furthermore, in the optical information recording medium 26 to which this embodiment is applied, as described above, the film thickness (D2) of the second light absorption layer 32 is the film thickness of the first light absorption layer 28 ( D1) is thicker (D2> D1). Specifically, the film thickness (D2) of the second light absorption layer 32 is adjusted to be 10% or more thicker than the film thickness (D1) of the first light absorption layer 28.
That is, the ratio (D2 / D1) of the film thickness (D2) of the second light absorption layer 32 to the film thickness (D1) of the first light absorption layer 28 is 1.1 or more (D2 / D1 ≧ 1. 1).
However, (D2 / D1) is usually 2.0 or less.

(Translucent reflective layer)
The translucent reflective layer 29 desirably has low light absorption, a light transmittance of 30% or more, and an appropriate light reflectance. For example, an appropriate transmittance and reflectance can be balanced by thinning a metal film having a high reflectance. Moreover, since the translucent reflective layer 29 is thin, a material having corrosion resistance is desirable. Furthermore, it is preferable to have a shielding property in order to prevent the organic dye from penetrating into the transparent intermediate layer 30.
Examples of the metal for forming the translucent reflective layer 29 include gold, silver, aluminum, and alloys containing these, and can be formed by means such as sputtering using these metals. Those containing Ag as a main component are particularly preferred from the viewpoint of low cost and high reflectance.

The translucent reflective layer 29 is preferably made of a material having small crystal grains because large crystal grains of the metal film cause reproduction noise. Since pure silver tends to have large crystal grains, Ag is preferably used as an alloy. In particular, Ag is the main component and contains at least one element selected from the group consisting of Ga, Bi, Ti, Zn, Cu, Pd, Au, Ca, In and rare earth metals in an amount of 0.1 atomic% to 5 atomic%. It is preferable. When two or more kinds of Ga, Bi, Ti, Zn, Cu, Pd, Au, Ca, In and rare earth metals are included, each of them may be 0.1 atomic% to 5 atomic%, but the total of these is 0.00. It is preferable that it is 1 atomic%-5 atomic%. Of the rare earth metals, neodymium is particularly preferred. Specific examples include AgPdCu, AgCuAu, AgCuAuNd, AgCuNd, AgCaCu, AgCaCu, AgIn, AgBi, and AgBiNd.
Moreover, Au has small crystal grains and is excellent in corrosion resistance and is preferable, but is more expensive than an Ag alloy. Further, as the translucent reflective layer 29, it is also possible to form a multilayer film by alternately stacking a low refractive index thin film and a high refractive index thin film using a material other than metal such as SiO ₂ and use it as a translucent reflective layer.

Examples of the method for forming the translucent reflective layer 29 include a sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like, and the sputtering method is preferable in terms of productivity.
Note that another layer such as an enhancement layer such as SiO ₂ , ZnS—SiO ₂ , Al ₂ O ₃ or an oxidation resistant layer may be provided between the first light absorption layer 28 and the translucent reflection layer 29. Good. Further, a protective layer may be formed on the translucent reflective layer 29, or a protective layer may not be formed. The protective layer may be any layer that can protect the light absorption layer and the reflective layer, and is formed of, for example, an ultraviolet curable resin, a silicone resin, or the like.

(Reflective layer)
The reflective layer 33 desirably has high reflectivity and excellent corrosion resistance. In order to increase the reflectance, the thickness of the reflective layer 33 is usually preferably 50 nm or more. More preferably, it is 80 nm or more. However, in order to increase the recording sensitivity, it is preferably thin to some extent, and is generally preferably 300 nm or less, more preferably 200 nm or less. If the thickness of the reflective layer 33 is excessively large, the second transparent substrate 34 may be warped.
Examples of the material of the reflective layer 33 include those having a sufficiently high reflectance at the wavelength of the reproduction light. Specifically, for example, metals such as Au, Al, Ag, Cu, Ti, Cr, and Ni can be used alone or as an alloy. Among these, Au, Al, Ag, or an alloy thereof is preferable. The components forming the alloy include Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Cu, Zn, Cd, Ga, In, Si, Ge, Te, Mention may be made of metals and metalloids such as Pb, Po, Sn, Bi and rare earth metals.

Among these, an Ag alloy is preferable because of its low cost, high reflectance, and excellent corrosion resistance. The Ag alloy is mainly composed of Ag, and contains at least one element selected from the group consisting of Ga, Bi, Ti, Zn, Cu, Pd, Au, Ca, In and rare earth metals in an amount of 0.1 atomic% to 5 atoms. % Content is preferable. When two or more kinds of Ga, Bi, Ti, Zn, Cu, Pd, Au, Ca, In and rare earth metals are included, each of them may be 0.1 atomic% to 5 atomic%, but the total of these is 0.00. It is preferable that it is 1 atomic%-5 atomic%. Of the rare earth metals, neodymium is particularly preferred. Specifically, AgPdCu, AgCuAu, AgCuAuNd, AgCuNd, AgCaCu, AgIn, AgBi, AgBiNd, and the like.
Examples of the method for forming the reflective layer 33 include a sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like, and the sputtering method is preferable in terms of productivity.

(Interface layer)
The interface layer 31 is formed on the second light absorption layer 32 of the second layer to shield the second light absorption layer 32 and the transparent intermediate layer 30 and prevent mixing of both layers. Provide. The transparent intermediate layer 30 is preferably made of a material that does not damage the second light absorption layer 32. However, when the transparent intermediate layer 30 is formed using a liquid ultraviolet curable resin, the ultraviolet curable resin is directly added to the transparent intermediate layer 30. In order to prevent the second light absorption layer 32 from being in contact with the second light absorption layer 32, it is desirable to provide an interface layer 31 between the transparent intermediate layer 30 and the second light absorption layer 32.

The material of the interface layer 31 is not particularly limited as long as it is not miscible with the second light absorption layer 32 and is not miscible with the transparent intermediate layer 30. Moreover, it may serve other functions, and may further sandwich other layers as necessary. As such a material, an inorganic substance such as a metal or a semiconductor, an oxide, a nitride, or a sulfide of a metal or a semiconductor is preferable, and a transparent inorganic substance such as a dielectric is more preferable. Specifically, oxides such as silicon oxide (particularly silicon dioxide), zinc oxide, cerium oxide, yttrium oxide; sulfides such as zinc sulfide and yttrium sulfide; nitrides such as silicon nitride; silicon carbide; Mixtures with sulfur; and alloys described below are suitable. A mixture of silicon oxide and zinc sulfide in a range of about (30:70) to (90:10) (weight ratio) is also suitable. A mixture of sulfur and yttrium dioxide with zinc oxide (Y ₂ O ₂ S—ZnO) is also suitable.

  The thickness of the interface layer 31 is preferably 3 nm or more, more preferably 5 nm or more. When the thickness of the interface layer 31 is excessively thin, shielding is insufficient. Moreover, 100 nm or less is preferable, More preferably, it is 50 nm or less. If the interface layer 31 is too thick, the light transmittance may be reduced, and in the case of a layer made of an inorganic material, it takes time to form a film, resulting in a decrease in productivity and an increase in film stress. Examples of the method for forming the interface layer 31 include a sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like. The sputtering method is preferable in terms of productivity.

(Transparent intermediate layer)
The transparent intermediate layer 30 is preferably made of a material that is transparent at the wavelength of the recording / reproducing light, has a high adhesive force, has a small shrinkage rate at the time of curing adhesion, and has high environmental preservation stability. In the present embodiment, since the focus servo is separately applied to the two light absorption layers (the first light absorption layer 28 and the second light absorption layer 32), the film thickness of the transparent intermediate layer 30 is accurately determined. It is preferable to control. The film thickness of the transparent intermediate layer 30 depends on the focus servo mechanism, and the distance tends to be smaller as the numerical aperture of the objective lens is higher.

In the present embodiment, in the optical information recording medium 26 of a blue laser (for example, wavelength (λ) 405 nm) on which two substrates having a thickness of 0.6 mm (first transparent substrate 27 and second transparent substrate 34) are bonded together. The film thickness of the transparent intermediate layer 30 is preferably 40 μm or less as described above. However, the film thickness of the transparent intermediate layer 30 is usually about 20 μm or more.
By setting the film thickness of the transparent intermediate layer 30 to 40 μm or less, when the blue laser is irradiated through the first transparent substrate 27, the first film thickness is made thinner than that of the second light absorption layer 32. It becomes possible to record barcode information on the light absorption layer 28 and the second light absorption layer 32 at the same time.

The transparent intermediate layer 30 is preferably made of a material that does not damage the translucent reflective layer 29. Moreover, you may form a well-known inorganic type or organic type protective layer between both layers.
Examples of the material of the transparent intermediate layer 30 include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, an ultraviolet curable resin (including a delayed curable type), and a pressure-sensitive double-sided tape. Among these, a solventless type ultraviolet curable resin is preferable because it is environmentally friendly and excellent in productivity. There are various types of ultraviolet curable resins, and any of them can be used as long as it is transparent.

  The transparent intermediate layer 30 can be formed by applying an ultraviolet curable resin and curing it by irradiating with ultraviolet light. As a coating method, a method such as a spin coating method, a screen printing method, a casting method, or the like is used as in the case of the first light absorption layer 28 and the like. Among these, a spin coating method is preferable. It is preferable to use an ultraviolet curable resin having a viscosity of 20 mPa · s to 1000 mPa · s at 10 ° C. to 40 ° C. without using a solvent.

  Examples of the ultraviolet curable resin include a radical ultraviolet curable resin and a cationic ultraviolet curable resin, both of which can be used. As the radical ultraviolet curable resin, all known compositions can be used, and a composition containing an ultraviolet curable compound and a photopolymerization initiator as essential components is used. As the ultraviolet curable compound, monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, and polyfunctional methacrylates can be used alone or in combination of two or more as polymerizable monomer components.

(Other layers)
In addition, the optical information recording medium 26 to which this exemplary embodiment is applied may be provided with a printing layer or a printing receiving layer on the second transparent substrate 34 opposite to the light incident side, as necessary.
Recording on the optical information recording medium 26 is performed by irradiating the first light absorption layer 28 and the second light absorption layer 32 provided on the optical information recording medium 26 with laser light. In the portion irradiated with the laser beam, thermal changes of the substrate such as decomposition of the dye, heat generation, carbonization, melting of the substrate, deformation due to absorption of laser beam energy occur. The recorded information is reproduced by reading the difference in reflectance between the portion where the thermal change has occurred and the portion where the thermal change has not occurred with the laser beam.

  In the present embodiment, the wavelength of the blue laser of the apparatus used for recording and reproduction is preferably 390 nm to 430 nm, and more preferably 400 nm to 420 nm. Also. The wavelength of the laser used for the writer for recording BCA (BCA recorder) may be any one that has absorption in the first light absorption layer 28 of the first layer and the second light absorption layer 32 of the second layer. For example, the thing of wavelength 390nm -430nm, 620nm-720nm, 780-830nm can be mentioned as an example. However, the wavelength of the BCA writer (BCA recorder) is not limited to this width.

Hereinafter, the present embodiment will be described more specifically based on examples. Note that this embodiment is not limited to the examples.
Example 1
A stamper A having a clockwise groove was mounted on an injection molding machine, and an optical information recording medium grade polycarbonate resin was injection molded to obtain a first transparent substrate. The first transparent substrate is a polycarbonate substrate having a diameter of 120 mm and a thickness of 0.59 mm, and a modulated wobble groove having a track pitch of 400 nm, a half-value width of 0.22 μm, and a depth of 45 nm is formed in the user information area.
Next, using the stamper B in which the counterclockwise groove was formed, a second transparent substrate was obtained by the same operation as described above. The second transparent substrate is a polycarbonate substrate having a diameter of 120 mm and a thickness of 0.59 mm, and a modulated wobble groove having a track pitch of 0.40 μm, a half-value width of 0.22 μm, and a depth of 35 nm is formed in the user information area. Yes.

Subsequently, a tetrafluoropropanol of a dye obtained by mixing an azo dye represented by the following chemical formula (1) and an additive represented by the chemical formula (2) in a ratio of 75:25 on the groove forming surface of the first transparent substrate. The solution (concentration 0.7% by weight, dye solution 1) was applied by spin coating. The dye film thickness in the groove portion was 36 nm. In addition, when apply | coating the said pigment | dye solution 1, the pigment | dye solution 1 was filtered with the filter and the impurity was removed.
Next, the first transparent substrate coated with the dye solution 1 was dried at 90 ° C. for 1 hour, and further cooled at room temperature for 1 hour. Thus, the first light absorption layer was formed on the first transparent substrate. Furthermore, a 11 nm thick translucent reflective layer made of an AgBi alloy was formed on the first light absorption layer by sputtering.

Next, an AgCuNd alloy was formed as a reflective layer on the groove forming surface of the second transparent substrate so as to have a thickness of 120 nm using a sputtering method. Next, a tetrafluoropropanol solution (concentration 1.1 wt%, dye solution 2) of a dye in which the azo dye represented by the chemical formula (1) and the additive represented by the chemical formula (2) are mixed in a ratio of 75:25. ) Was applied by spin coating. The dye film thickness in the groove portion was 45 nm. In addition, when apply | coating the said pigment | dye solution 2, the pigment | dye solution 2 was filtered with the filter and the impurity was removed.
Next, the second transparent substrate coated with the dye solution 2 was dried at 90 ° C. for 1 hour, and further cooled at room temperature for 1 hour. Thus, the second light absorption layer was formed on the reflective layer of the second transparent substrate. Furthermore, an interface layer made of ZnS—SiO ₂ and having a thickness of 10 nm was formed on the second light absorption layer by sputtering.

  Subsequently, a radical polymerization type UV resin was applied on the semitransparent reflective layer of the first transparent substrate by a spin coating method, and was set in a bonding apparatus. Next, it installed in the bonding apparatus so that the interface layer of a 2nd transparent substrate might face the radical polymerization type UV resin application surface of a 1st transparent substrate. The inside of the apparatus was evacuated, and both disks were bonded so that bubbles were not generated in the transparent intermediate layer. The bonded disc was taken out from the bonding apparatus, and irradiated with UV from the first transparent substrate side and cured to obtain an optical information recording medium A on which a 25 μm thick translucent intermediate layer was formed. In the obtained optical information recording medium A, when information is recorded in the information areas of the first light absorption layer and the second light absorption layer with a laser beam having a wavelength of 405 nm, the reflectance of the recorded mark is not recorded. The recording was Low to High recording, which was higher than the reflectance.

  The optical information recording medium A thus obtained is focused on the first light absorption layer with a recording power of 190 mW with a BCA recording machine having a wavelength of 407 nm, and the first transparent layer is first transparent from the first light absorption layer side. A bar code signal was recorded over a substrate with a radius of 22.20 mm to 23.20 mm. Table 1 shows the evaluation results of the signals obtained from BCA.

(Example 2)
In the optical information recording medium A used in Example 1, an optical information recording medium B was obtained by the same operation as in Example 1 except that the film thickness of the transparent intermediate layer was changed to 35 μm. Next, with respect to the optical information recording medium B, the first light absorption layer is focused by the same operation as in Example 1, and the radius 22 is passed from the first light absorption layer side through the first transparent substrate. A bar code signal was recorded between 20 mm and 23.20 mm. Table 1 shows the evaluation results of the signals obtained from BCA.

(Comparative Example 1)
In the optical information recording medium A used in Example 1, the dye application concentration for forming the first light absorption layer was 0.85 wt%, and the dye application for forming the second light absorption layer was used. An optical information recording medium C was obtained by the same operation as in Example 1 except that the concentration was changed to 0.88% by weight. Next, with respect to the optical information recording medium C, the first light absorption layer is focused by the same operation as in Example 1, and the radius 22 is passed from the first light absorption layer side through the first transparent substrate. A bar code signal was recorded between 20 mm and 23.20 mm. Table 1 shows the evaluation results of the signals obtained from BCA.

(Comparative Example 2)
In the optical information recording medium A used in Example 1, an optical information recording medium D was obtained by the same operation as in Example 1 except that the film thickness of the transparent intermediate layer was changed to 60 μm. Next, with respect to the optical information recording medium B, the first light absorption layer is focused by the same operation as in Example 1, and the radius 22 is passed from the first light absorption layer side through the first transparent substrate. A bar code signal was recorded between 20 mm and 23.20 mm. Table 1 shows the evaluation results of the signals obtained from BCA.

(Comparative Example 3)
Similar to the optical information recording medium A used in Example 1, a first transparent substrate in which a first light absorption layer and a semitransparent reflective layer were formed on the groove forming surface of the first transparent substrate was obtained. Thereafter, with respect to the first transparent substrate thus obtained, a radius of 22.20 mm to 23.20 mm from the first light absorption layer side through the first transparent substrate at a recording power of 190 mW with a BCA recording machine having a wavelength of 407 nm. A bar code signal was recorded.
Next, similarly to the optical information recording medium A used in Example 1, a second transparent substrate in which a reflective layer, a second light absorption layer, and an interface layer are formed on the groove forming surface of the second transparent substrate. Obtained. Thereafter, the same barcode signal was recorded on the second transparent substrate thus obtained with a BCA recorder having a wavelength of 407 nm at a recording power of 190 mW and a radius of 22.20 mm to 23.20 mm from the interface layer side.

  Subsequently, in the same manner as in the optical information recording medium A used in Example 1, a radical polymerization type UV resin was applied on the semitransparent reflective layer of the first transparent substrate by a spin coating method and installed in a bonding apparatus. Next, it installed in the bonding apparatus so that the interface layer of a 2nd transparent substrate might face the radical polymerization type UV resin application surface of a 1st transparent substrate. The inside of the apparatus was evacuated, and both disks were bonded so that bubbles were not generated in the transparent intermediate layer. The bonded disc was taken out from the bonding apparatus, and cured by applying UV irradiation from the first transparent substrate side to obtain an optical information recording medium E on which a semitransparent intermediate layer having a thickness of 25 μm was formed. Table 1 shows the evaluation results of the signals obtained from BCA.

(BCA signal evaluation)
Each optical information recording medium prepared in each of Example 1, Example 2, and Comparative Examples 1 to 3 is a tester having an optical pickup having a laser beam having a wavelength of 405 nm and a lens having a numerical aperture of 0.65. The BCA signal was reproduced with the focus on the layer and the second layer and the tracking was removed, and the start position and end position of the BCA signal of the first layer and the second layer, and the amplitude of the reproduction signal were measured.
The BCA signal start position and end position are measured by attaching a measurement disk to the tester, focusing on the first layer, taking the BCA signal from the reference position into the digital oscilloscope, and setting the BCA start position of the first layer relative to the reference position. It was measured. Without removing the disc from the tester, the focus was switched to the second layer. Similarly, the BCA signal was taken into the digital oscilloscope from the reference position, and the BCA start position of the second layer was measured with respect to the reference position. From each start position and end position, ΔS was obtained from equation (1).
The jitter of the BCA signal was obtained as a standard deviation σ with respect to the clock by inputting the tester signal to the time interval analyzer.

FIG. 4 is a diagram illustrating an example of a BCA signal, a BCA start position, a BCA end position, and a BCA amplitude. As shown in FIG. 4, 36 is a BCA start position, 37 is a BCA end position, 38 is a BCA amplitude, and 39 is a reflectance.
The BCA amplitude (%) was obtained by the following formula using the BCA amplitude 38 and the reflectance 39.
BCA amplitude (%) = (BCA amplitude 38 / reflectance 39) × 100
The results are shown in Table 1.

  The results shown in Table 1 will be described. First, in an optical information recording medium provided with two light absorption layers containing an organic dye, the thickness of the first light absorption layer on the near side as viewed from the incident side of the recording / reproducing light is viewed from the incident side of light. Barcode information of the same management information in each of the first layer and the second layer by making it thinner than the second light absorption layer on the back side and making the film thickness of the transparent intermediate layer 40 μm or less. Can be formed at the same radial position (ΔS = 0) (Example 1 and Example 2).

  Next, in the signal obtained from the BCA formed in this way, the signal amplitude obtained from the BCA of the first layer becomes smaller than the signal amplitude obtained from the BCA of the second layer, and the jitter of the BCA of the second layer is further obtained. As a result, it can be seen that barcode information with high signal quality can be reproduced from the BCA of the second layer.

  On the other hand, in an optical information recording medium provided with two light absorption layers containing an organic dye, the thickness (45 μm) of the first light absorption layer on the near side when viewed from the incident side of the recording / reproducing light is the light incident side. When the thickness is larger than the film thickness (36 μm) of the second light absorption layer on the back side as viewed from (Comparative Example 1), the BCA amplitude of the barcode information recorded in the BCA formation region of the second light absorption layer is It can be seen that the jitter is reduced and the jitter becomes poor.

  Further, when the film thickness of the transparent intermediate layer is 40 μm or more (60 μm: Comparative Example 2), when the blue laser is irradiated from the first light absorption layer side through the first transparent substrate, the film of the transparent intermediate layer Since the thickness is too thick, it is difficult to record barcode information on the first light absorption layer and the second light absorption layer at the same time. As a result, it is understood that the barcode information cannot be sufficiently recorded in the second light absorption layer, so that the BCA amplitude of the second layer is small (3%) and the jitter is 10% or more.

  Further, when barcode information is recorded on each of the first light absorption layer and the second light absorption layer and then bonded together (Comparative Example 3), the barcode information of the first light absorption layer And the barcode information of the second light absorption layer do not match (ΔS = 315 μm). Therefore, when reproducing the barcode information of each layer, the respective barcode information signals interfere with each other. As a result, it can be seen that the BCA amplitude decreases and the jitter becomes poor (4.5%).

As described above in detail, in an optical information recording medium having two light absorption layers containing a light absorbing material that can be recorded and reproduced by irradiating with a blue laser from one side, the front side as viewed from the incident side of the recording and reproduction light. The film thickness of the first light absorption layer is made thinner than the film thickness of the second light absorption layer on the back side when viewed from the light incident side, and the film thickness of the transparent intermediate layer is made 40 μm or less. Can form a BCA in which barcode information of the same management information is recorded at the same radial position in each of the first layer and the second layer. Thus, the same barcode information is recorded at the same radial position. When the barcode information of each layer is reproduced by forming the BCA, the interference of the signals of the respective barcode information is strengthened, the BCA amplitude is increased, and the jitter is also improved. The high signal It is possible to reproduce in quality.

It is a figure for demonstrating the optical information recording medium with which this Embodiment is applied. It is a figure explaining the cross-sectional structure of the optical information recording medium with which this Embodiment is applied. It is a figure explaining the cross-section of the area | region in which BCA of the optical information recording medium to which this Embodiment is applied was formed. It is a figure explaining the example of a BCA signal, a BCA start position, and an amplitude.

Explanation of symbols

1, 12, 26, optical information recording medium, 2, 4, 6, 14, 16, 18 ... first layer mirror region, 7, 9, 11, 20, 22, 24 ... second layer mirror region, , 17 ... Information area of the first layer, 10, 23 ... Information area of the second layer, 3, 15 ... BCA of the first layer, 8, 21 ... BCA of the second layer, 13, 27 ... First transparent substrate, DESCRIPTION OF SYMBOLS 19, 30 ... Transparent intermediate layer, 25, 34 ... 2nd transparent substrate, 28 ... 1st light absorption layer, 29 ... Semi-transparent reflective layer, 31 ... Interface layer, 32 ... 2nd light absorption layer, 33 ... reflective layer

Claims (12)

An optical information recording medium provided with two light-absorbing layers having an information area in which user information can be recorded and reproduced along a concentric or spiral track by a blue laser beam irradiated from one side,
A burst cutting area (BCA) of a first layer provided inside the user information area of the first light absorption layer on the near side as viewed from the light incident side and recording predetermined management information as barcode information; ,
The burst cutting area (BCA) of the first layer is provided in the second light absorption layer on the back side when viewed from the light incident side and at the same radial position as the burst cutting area (BCA) of the first layer. A second layer burst cutting area (BCA) in which the same management information as the management information recorded in
An optical information recording medium comprising: The recording start position (BCA2S) at the center of the width of the burst cutting area (BCA) of the second layer and the recording start position (BCA1S) at the center of the width of the burst cutting area (BCA) of the first layer are as follows: The optical information recording medium according to claim 1, wherein the relationship expressed by the following formula (1) is satisfied.
ΔS = (BCA2S) − (BCA1S) ≦ 15 μm Formula (1)
(However, in equation (1), ΔS is the difference (unit: μm) between (BCA2S) and (BCA1S).)   3. The optical information according to claim 1, wherein a signal amplitude obtained from the first layer burst cutting area (BCA) is smaller than a signal amplitude obtained from the second layer burst cutting area (BCA). recoding media.   The first light absorption layer and the second light absorption layer contain an organic dye, and the film thickness of the second light absorption layer is thicker than the film thickness of the first light absorption layer. The optical information recording medium according to claim 1, wherein:   The reflectance of the burst cutting area (BCA) of the first layer is higher than the reflectance of the region where the burst cutting area (BCA) of the first layer before the management information is recorded is Low to High. The reflectivity of the second layer burst cutting area (BCA) is the reflectivity of the area where the second layer burst cutting area (BCA) is formed before the management information is recorded. 5. The optical information recording medium according to claim 1, wherein the optical information recording medium is a Low to High recording.   6. The transparent intermediate layer having a film thickness of 40 μm or less is provided between the first light absorption layer and the second light absorption layer. 6. Optical information recording medium. An optical information recording medium having two light-absorbing layers containing an organic dye,
A first light-absorbing layer provided on the front side when viewed from the incident side of light irradiated from one side;
A second light-absorbing layer provided on the back side as viewed from the light incident side and having a film thickness (D2) thicker than the film thickness (D1) of the first light-absorbing layer;
A transparent intermediate layer having a thickness of 40 μm or less provided between the first light absorption layer and the second light absorption layer;
An optical information recording medium comprising at least a burst cutting area (BCA) in which predetermined management information is recorded in the second light absorption layer.   8. The optical information recording medium according to claim 7, wherein the thickness (D2) of the second light absorption layer is 10% or more larger than the thickness (D1) of the first light absorption layer.   It is Low to High recording in which the reflectivity of the burst cutting area (BCA) is higher than the reflectivity of the area forming the burst cutting area (BCA) before the predetermined management information is recorded. The optical information recording medium according to claim 7.   Further, the management recorded in the burst cutting area (BCA) at the same radial position as the burst cutting area (BCA) formed in the second light absorption layer of the first light absorption layer. 8. The optical information recording medium according to claim 7, further comprising another burst cutting area (BCA) in which the same management information as the information is recorded. A method for producing an optical information recording medium having a two-layer light absorbing layer containing an organic dye that can be recorded and reproduced by light,
The light is incident on the transparent substrate through the first light absorption layer on the near side as viewed from the light incident side, and the first light absorption layer and the transparent intermediate layer having a thickness of 40 μm or less. A second light absorption layer is formed on the back side when viewed from the side,
Irradiate a blue laser from the light incident side through the transparent substrate,
A burst cutting area (BCA) in which predetermined management information is recorded as barcode information is simultaneously formed in the first light absorption layer and the second light absorption layer. A method for manufacturing a medium.   The ratio (D2 / D1) of the film thickness (D2) of the second light absorption layer to the film thickness (D1) of the first light absorption layer is 1.1 or more (D2 / D1 ≧ 1.1) The method of manufacturing an optical information recording medium according to claim 11, wherein:

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