JP2003248969A - Optical disc and optical disc manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disc that has stabilized characteristics showing a constant reflection and modulation in any location on a disc surface. <P>SOLUTION: In an optical disc that has a recording layer consisting of an organic dye and metal reflector and is capable of recording and reproducing information by a laser beam, (1) the organic dye contents of the recording layer is made radially uneven on the disc, (2) ratio of the recording layer thickness of grooves and lands is made radially uneven, (3) reflector layer thickness is made radially uneven on the disc, and (4) content ratio of the reflector layer is made radially uneven. Above procedures cancel optical characteristic differences unavoidable on the disc made by using a conventional method material, and it is made possible to obtain the optical characteristics stabilized all over the disc. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk capable of optically recording and reproducing information, and in particular, an optical disk in which a recording layer is changed by irradiation of laser light or the like, and a method for manufacturing the same. The manufacturing apparatus is related.

[0002]

2. Description of the Related Art In recent years, with the spread of CDs, recordable optical disks conforming to the CD standard have been developed and used. The CD-R generally uses a transparent resin substrate having a spiral groove (guide groove) on one side, and an organic dye solution is applied onto the transparent resin substrate by a spin coater and then the solvent is dried to form a recording layer, Further, a reflective layer formed by metal sputtering or the like, and a protective layer formed by applying and curing an ultraviolet curable resin or the like with a spin coater or the like are provided thereon.

Recently, so-called DVDs have been developed and put into practical use with the aim of further increasing the density of information. Like a CD, a DVD has a molding machine on which a pit having a track pitch of 0.74 μm and a minimum pit length of 0.40 μm is formed on a resin substrate having a thickness of 0.6 mm. In order to ensure the strength of the
It is manufactured by laminating m resin substrates and integrating them. As for the DVD, a write-once type DVD-R is commercially available, like the CD-R.

FIG. 1 schematically shows a typical structure of a DVD-R. The DVD-R shown in FIG. 1 includes a transparent resin substrate 1 having a groove 1 a, a recording layer 2 containing an organic dye, a reflective layer 3, an adhesive layer 4, and a resin substrate 5 having the same thickness as the substrate 1. It is composed. For easy understanding, the optical disc of FIG. 1 is illustrated such that the ratio of the thickness of each layer is different from the actual one.

Recording on the recording layer 2 is performed by irradiating a laser beam having a predetermined wavelength from the substrate side to the recording layer to change, for example, decompose the organic dye, and / or interference of the recording layer. This is performed by forming pits corresponding to information by utilizing the change in structure.
Like the CD-R, the recording layer 2 can be formed by a method of spin coating a solution in which an organic dye is dissolved in an appropriate solvent, or can be formed by vacuum vapor deposition of an organic dye or the like.

[0006]

DISCLOSURE OF THE INVENTION CD-R or DVD
As a problem that may occur with respect to −R, there is a problem that the disc characteristics, particularly the reflectance and the modulation degree, are different between the inner circumference and the outer circumference of the disk. The term "reflectance" as used herein refers to the reflectance used when light (for example, laser light) used for recording and reproducing information on the recording layer of the optical disc, that is, light having a recording and reproducing wavelength is irradiated. In the present specification including the following description, the term "reflectance" simply means the reflectance of light having a recording / reproducing wavelength.

The CD-R is one of the reasons why the above problems occur.
Alternatively, the birefringence of the resin substrate and / or the depth of the groove formed in the substrate forming the DVD-R may not be constant in the radial direction of the substrate.

The disk-shaped substrate is formed by injection molding in which a resin is radiated from a central portion of a mold (also called a stamper). Concavities and convexities are formed on the stamper so that desired grooves are formed on the substrate. The birefringence of the substrate is generally the largest at the inner circumference of the substrate and tends to decrease toward the outer circumference. This is considered to be due to the fact that a uniform molecular weight distribution cannot be obtained in the radial direction of the substrate due to the pressure conditions and the like when the substrate is injection molded. Further, the depth of the groove formed on the substrate tends to become shallower from the center toward the outer periphery. This is because when forming the groove by injection molding,
It is considered that the unevenness formed on the stamper is not sufficiently transferred on the outer peripheral portion, that is, the transfer rate is low.

Both the portion having a small birefringence and the portion having a shallow groove depth are portions having a high reflectance in the finally obtained optical disc. Therefore, the reflectance of the optical disc generally increases from the inner circumference toward the outer circumference. In addition, in the part where the depth of the groove is shallow,
In the finally obtained optical disc, it becomes a portion with a small modulation degree.

In order to solve the problem of birefringence, for example, the composition of the material forming the substrate has been changed. However, in order to achieve a certain birefringence in a substrate after injection molding, it is necessary to select a special material, and such a material is generally expensive. Further, in order to solve the problem that the depth of the groove is not constant, for example, a special stamper is used. However, the use of a special stamper is disadvantageous in terms of cost and time, because the production of a special stamper requires skill.

For a write-once type optical disc, it is required to secure a certain disc characteristic. Therefore, one optical disk needs to have a predetermined reflectance and modulation degree at every location. An optical disc that does not have a predetermined reflectance and modulation degree is regarded as not satisfying the standard and cannot be a product.

As described above, the disc characteristics of the optical disc are defined by the standard so as to take a value within a certain range at any position. CD-R currently on the market
Although the DVD-R and the DVD-R have a difference in reflectance between the inner circumference and the outer circumference, the difference is within an allowable range according to the standard. However, optical discs are required to be further improved, and optical discs having more uniform disc characteristics throughout are constantly required. The present invention has been made in view of such circumstances, and even when a substrate made of an ordinary material, which is manufactured without using a special stamper and injection molding technology, is used, the reflectance, the degree of modulation, etc. An object of the present invention is to provide an optical disc having excellent disc characteristics which is constant over the entire length.

[0013]

In order to solve the above-mentioned problems, the present invention is an optical disc having a recording layer made of an organic dye as a first optical disc, and the recording layer comprises two or more kinds of organic dyes. Provided is an optical disc that contains components as components and the component ratio in the recording layer is not constant in the radial direction of the disc.

The first optical disc is characterized in that the recording layer contains two or more kinds of organic dyes as constituent components, and the component ratio in the recording layer is not constant in the radial direction of the disc. Therefore, in the recording layer of the first optical disc, the portions having the same component ratio exist in concentric circles. The component ratio is indicated by the ratio (weight basis) of each organic dye in the recording layer. When the component ratio is not constant in the radial direction of the disc, 1) when the ratio of each organic dye contained in the recording layer is not constant in the radial direction of the disc, and 2) when the organic dye contained in the recording layer is There are three types, and the ratio of one type of organic dye is constant over the entire radial direction of the disc, and the case where the ratio of the remaining two types of organic dye changes in the radial direction of the disc is included.

When the component ratio changes in the recording layer, the optical characteristics of the recording layer, especially the reflectance changes. Therefore, if the component ratio in the recording layer is changed in the radial direction of the disc such that the reflectance of the recording layer becomes larger at the inner periphery of the recording layer and becomes smaller at the outer periphery of the recording layer, the disc derived from the ordinary optical disc substrate will be obtained. The changes in the optical characteristics in the radial direction are canceled out. Thus, the first optical disc of the present invention,
By changing the component ratio in the recording layer as desired, the overall optical characteristics are made constant in the radial direction of the disk, and stable recording / reproducing characteristics are exhibited in the disk surface.

In order to solve the above problems, the present invention provides a second
An optical disc having a recording layer made of an organic dye, wherein the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer is not constant in the radial direction of the disc.

In the second optical disc, the ratio of the thickness of the recording layer located on the land of the substrate to the thickness of the recording layer located on the groove of the substrate is not constant in the radial direction of the disc. Characterize. Therefore, in the recording layer of the second optical disc, the portions in which the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer is the same are substantially concentric circles. Here, grooves and lands are used in their ordinary meaning. The ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer is the ratio of the thickness of the recording layer in the groove portion to the thickness of the recording layer in a certain groove portion. It can be regarded as the size of the level difference of the recording layer. The greater the thickness of the land portion relative to the thickness of the groove portion of the recording layer, the greater the step difference between the two portions. The size of the step between the two parts can be known from the push-pull signal, for example.

A change in the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer also changes the optical characteristics of the recording layer, particularly the reflectance. In general, the reflectance tends to decrease as the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer increases, that is, the step difference between the two portions increases. Therefore, if the ratio of the thickness of the land portion to the thickness of the groove portion in the recording layer is changed so as to increase toward the outer peripheral side, the change in the optical characteristics of the disc in the radial direction due to the ordinary optical disc substrate is prevented. Offset. Thus, in the second optical disc of the present invention, by changing the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer as desired,
The overall optical characteristics are made constant in the radial direction of the disk so that stable recording / reproducing characteristics are exhibited in the disk surface.

Alternatively, in the second optical disc, the recording layers are arranged at different positions from the center of the substrate.
From the above nozzles, organic dye solutions having different viscosities are dropped, and spin coating is performed to identify the optical disc as a layer. The optical disc specified in this way has a recording layer whose optical characteristics are not constant in the radial direction of the disc by applying organic dye solutions having different viscosities at different places so as to form concentric circles, for example.

In order to solve the above problems, the present invention is an optical disc having a recording layer made of an organic dye and a reflective layer as a third optical disc, wherein the thickness of the reflective layer is not constant in the radial direction of the disc. I will provide a.

The third optical disc is characterized in that the thickness of the reflective layer is not constant in the radial direction of the disc.
Therefore, in the reflective layer of this third optical disc,
The parts having the same thickness are concentrically formed.

The thickness of the reflective layer affects the characteristics of the optical disk, particularly the reflectance and the degree of modulation. Generally, when the thickness of the reflective layer is large, the reflectance is large and the degree of modulation is small. When the thickness of the reflective layer is small, the reflectance is small and the degree of modulation is large. Therefore, for example, if the thickness of the reflective layer is increased on the inner circumference of the disk and decreased on the outer circumference, the change in the optical characteristics of the disk in the radial direction due to the ordinary optical disk substrate is offset. As described above, in the third optical disc of the present invention, by changing the thickness of the reflective layer as desired, the entire optical characteristic is made constant in the radial direction of the disc, and stable recording / reproducing characteristics are achieved in the disc surface. Is shown.

In order to solve the above-mentioned problems, the present invention provides a fourth optical disc, which is an optical disc having a recording layer made of an organic dye and a reflective layer, wherein the reflective layer contains two or more kinds of elements as constituent components. Provided is an optical disc in which the component ratio in the reflective layer is not constant in the radial direction of the disc.

The fourth optical disc is characterized in that the reflective layer contains two or more kinds of elements as constituent components, and the component ratio in the reflective layer is not constant in the radial direction of the disc. The component ratio is indicated by the ratio (weight basis) of each element in the reflective layer. Therefore, in the reflective layer of the fourth optical disc, the portions having the same component ratio are concentrically present. When the component ratios are not constant in the radial direction of the disc, 1) when the ratio of each element contained in the reflective layer is not constant in the radial direction of the disc, and 2) when three types of elements are contained in the reflective layer. That is, the ratio of one kind of element is constant over the entire radial direction of the disk, and the ratio of the remaining two kinds of elements changes in the radial direction of the disk.

The component ratio in the reflective layer affects the optical characteristics of the optical disk, especially the reflectance. Therefore, if the component ratio in the reflective layer is changed in the radial direction of the disc, for example, the reflectance of the reflective layer becomes large at the inner circumference of the disc and becomes small at the outer circumference, the disc derived from the ordinary optical disc substrate is obtained. The changes in the optical characteristics in the radial direction are canceled out. Thus, in the fourth optical disc of the present invention, by changing the component ratio in the reflective layer as desired,
The overall optical characteristics are made constant in the radial direction of the disk so that stable recording / reproducing characteristics are exhibited in the disk surface.

In the optical disk of the present invention, the nonuniformity of the optical characteristics inevitably caused in the substrate manufactured by the ordinary method and material is made nonuniform in the composition ratio in the recording layer, and the groove portion of the recording layer is formed. The unevenness of the ratio of the thickness of the land portion to the thickness, the unevenness of the thickness of the reflection layer, or the unevenness of the component ratio in the reflection layer cancels each other out, and the reflectance and the degree of modulation are reduced. Is an optical disc in which is substantially constant in the radial direction of the disc. It is also possible to combine two or more of, which allows more precise control of the optical properties of the optical disc.

The present invention is also a method for manufacturing the above-mentioned first optical disc, which comprises forming the recording layer by spin coating of an organic dye solution, wherein the spin coating is performed at a position different in distance from the center of the substrate. A method for manufacturing an optical disk, characterized in that an organic dye solution having a different organic dye composition is dropped from two or more nozzles arranged in each of the nozzles, and each nozzle is reciprocally moved in the radial direction of the substrate. To do.

In this manufacturing method, two or more organic dye solutions having different organic dye compositions are used, and each organic dye solution is dropped from different nozzles arranged at different distances from the center of the substrate and spun. It is characterized in that a recording layer is formed by coating. The difference in the composition of the organic dye in the organic dye solution means that the type and / or the blending ratio of the organic dye contained in the solution are different. According to this manufacturing method, organic dye solutions having different organic dye compositions are applied to different regions in the radial direction of the substrate. This makes it possible to obtain a recording layer in which the component ratio in the recording layer is not constant in the radial direction of the disc.

The present invention is also a method for manufacturing the above second optical disk, which comprises forming the recording layer by spin coating of an organic dye solution, wherein the spin coating is performed at a position different in distance from the center of the substrate. Provided is a method for manufacturing an optical disk, characterized in that organic dye solutions having different viscosities are dropped from two or more nozzles arranged in the same manner, and each nozzle is reciprocally moved in the radial direction of the substrate. The organic dye solutions having different viscosities are preferably organic dye solutions having different solvents or solvent compositions.
The term “different solvent” means that the type of solvent that dissolves the organic dye is different. The term “different solvent composition” means that when the solution contains two or more kinds of solvents, the kinds and / or blending ratios of the solvents are different. The ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer changes depending on the viscosity of the organic dye solution during spin coating. Therefore, according to this manufacturing method, it is possible to obtain a recording layer in which the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer is not constant in the radial direction of the disc.

The present invention is also a method for manufacturing the above-mentioned third optical disc, which comprises forming the reflective layer by sputtering, wherein the sputtering is performed between the target and the substrate by a shield plate covering a part of the substrate. The present invention provides a method for manufacturing an optical disc, which is characterized in that the optical disc is placed on the substrate and is performed while rotating the substrate. Here, the substrate to be sputtered has a recording layer formed thereon. In the present specification including the following description, the term “substrate” as an object to be sputtered refers to a substrate on which a recording layer is formed.

In this manufacturing method, a part of the substrate is covered with a shielding plate, and sputtering is performed while rotating the substrate. The target material does not adhere to the portion of the substrate covered by the shield plate. Therefore, if a predetermined portion is covered with the shield plate longer than other portions during sputtering, the thickness of the portion becomes smaller. If sputtering is performed while the substrate is stationary with respect to the shield plate, a portion where the reflective layer is not formed is generated on the substrate, so that the substrate is rotated. In addition, the shape of the shielding plate is such that the substrate is 1
It is necessary to make the shape such that there is no part covered with the shielding plate during the rotation. When such a portion is present on the substrate, the target material does not adhere to that portion and the reflective layer is not formed.

As described above, the use of the shielding plate prevents the reflective layer from being formed to have a uniform thickness. Therefore, the thickness of the reflective layer can be changed as desired in the radial direction of the disc by appropriately selecting the shape of the shielding plate.

The present invention is also a method for manufacturing the above-mentioned fourth optical disk, which comprises forming the reflective layer by sputtering, in which the substrate is moved by using a plurality of independent targets having different compositions. Characterized in that a shield plate located between the target and the substrate and covering a part of the substrate is arranged to rotate the substrate when performing sputtering with each target in order. An optical disc manufacturing method is provided.

In this manufacturing method, a plurality of independent targets having different compositions are used. The term "independent target" means that when a target is sputtered to form a thin film on a substrate, a substance derived from another target does not participate in the formation of the thin film. That is, in this manufacturing method, sputtering is almost always performed using one target.

In this manufacturing method, the reflective layer is formed by moving the substrate and sequentially performing sputtering with each target. For example, three targets T
When 1, T2 and T3 are used, the substrate is repeatedly moved and the sputtering is repeated from T1 to T3, and a reflective layer having a multi-layer structure is formed by repeatedly forming T1 film-T2 film-T3 film in this order. Form. When the reflective layer is formed so as to have a multilayer structure, the film derived from each target is not unevenly distributed in the thickness direction, and the component ratio of the reflective layer in the thickness direction becomes relatively uniform.

Further, in this manufacturing method, at the time of sputtering with at least one target, a shield plate which is located between the target and the substrate and covers a part of the substrate is arranged, and the sputtering is performed while rotating the substrate. I do. The function of the shielding plate is as described above in relation to the method for manufacturing the second optical disc. By using a plurality of targets and using at least one shield, it is possible to form a reflective layer having different component ratios in the radial direction of the disc. If no shielding plate is provided, the reflective layer formed will have a constant component ratio over the entire disc, even if a plurality of targets are used.

The present invention is also the method for manufacturing the above-mentioned fourth optical disc, which comprises forming the reflection layer by sputtering, and the sputtering is carried out using a target whose composition is not constant in the radial direction. A method for manufacturing an optical disc is provided. According to this manufacturing method, it is possible to form a reflective layer containing two or more kinds of elements and having a non-constant composition ratio in the radial direction of the disk with a single target.

The present invention is also an apparatus for manufacturing the above-mentioned first or second optical disk, including a spin coater, wherein the spin coaters are arranged at different positions from the center of the substrate. There is provided an optical disk manufacturing apparatus including a nozzle and a mechanism for reciprocating each nozzle in a radial direction of a substrate. This manufacturing equipment
It is used to carry out the method of manufacturing the first or second optical disc described above.

The present invention is also an apparatus for manufacturing the above third optical disk, including a sputtering apparatus, wherein the sputtering apparatus is located between the target and the substrate when the target and the substrate are arranged. There is provided an optical disk manufacturing apparatus characterized by including a shielding plate which covers a part of the optical disc, and a mechanism for rotating the substrate. This manufacturing apparatus is used to carry out the method for manufacturing the third optical disc described above.

The present invention is also an apparatus for manufacturing the above-mentioned fourth optical disc, which includes a sputtering apparatus, wherein the sputtering apparatus sequentially sputters a substrate with a) a plurality of independent targets having different compositions, and b) each target. Mechanism for moving the substrate so that c) at least 1
There is provided an optical disk manufacturing apparatus including a shield plate located between the target and the substrate to cover a part of the substrate when sputtering with one target, and d) a mechanism for rotating the substrate on its own axis. This manufacturing apparatus is used to carry out the method of manufacturing the fourth optical disc described above.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the above-described first to fourth optical disks of the present invention will be described below together with their manufacturing methods and manufacturing apparatuses.

The first optical disc of the present invention has two recording layers.
An organic dye of more than one kind is contained as a constituent component, and the component ratio in the recording layer is not constant in the radial direction of the disc. The organic dye is selected from those used as the organic dye forming the recording layer of the optical disc.

The two or more kinds of organic dyes constituting the recording layer are organic dyes having different maximum absorption wavelengths (λmax). Here, λmax is a value measured in a film-formed state. The recording layer is formed with only one type of organic dye,
When this is irradiated with light of a recording / reproducing wavelength, the recording layer has different optical characteristics (especially reflectance) depending on the λmax of the organic dye film.
Indicates. In addition, when a recording layer is formed of two or more kinds of organic dyes having different λmax of the film and the recording layer is irradiated with light having a recording / reproducing wavelength, one kind of the recording layer is formed according to the ratio of each organic dye to the recording layer. It exhibits optical characteristics different from those of recording layers formed of organic dyes. Therefore, the recording layer in which the component ratio in the recording layer is not constant in the radial direction of the disc exhibits different reflectance in the radial direction of the disc depending on the component ratio. The recording / reproducing wavelength is 700 to 800 nm for CD-R and generally 780 nm.
630-680 nm for D-R, generally 650 nm
Is.

Generally, the larger the λmax of the film of the organic dye (that is, the longer the wavelength is), the lower the reflectance of the optical disk having the recording layer formed of the dye. Therefore,
The recording layer may be formed by combining an organic dye having a small λmax of the film and an organic dye having a large λmax of the film, depending on the type of the optical disc. For example, in the case of producing a CD-R, a dye having a λmax of the film in the range of 700 to 770 nm and a dye having a λmax of the film in the range of 750 to 780 nm should be combined to form a recording layer. Is preferred.
When producing a DVD-R, the λmax of the film is 5
Dyes in the range of 50-600 nm and film λmax of 5
It is preferable to form a recording layer by combining with a dye in the range of 80 to 630 nm.

The recording layer is preferably composed of 2 to 5 kinds of organic dyes having different λmax of the film. Even if the number of organic dyes is more than 5, the effect of the present invention of changing the optical characteristics of the recording layer in the radial direction of the disc remains unchanged.

When attention is paid to the main organic dye of the recording layer, the main organic dye is recorded on the outer peripheral portion of the disk with respect to the ratio of the main organic dye to the recording layer on the inner peripheral portion of the disk. It is preferable that the proportion of the layers is different by 10% or more. That is, it is preferable that the proportion of the main organic dye in the outer peripheral portion is 10% or more higher or lower than the proportion of the main organic dye in the inner peripheral portion. The reflectance of the optical disk does not change significantly in the radial direction of the disk when the ratio of the main organic dyes does not differ by 10% or more between the inner and outer circumferences of the disk. When two or more main organic dyes are present in the recording layer,
It is preferable that the proportion of the at least one main organic dye in the recording layer at the inner peripheral portion of the disc is different from that in the recording layer at the outer peripheral portion of the disc by 10% or more.

Here, the main organic dye is an organic dye that ensures good recording and reproduction of a signal by using a laser beam having a wavelength corresponding to the type of optical disc. Satisfactorily recording / reproducing a signal means that the degree of modulation and the jitter characteristic satisfy the values defined by the standard when the recorded signal is reproduced. The main organic dye is an organic dye having a film having a λmax within a predetermined range and having a film reflectance of a predetermined value or more, and varies depending on the type of optical disc. For example, when making a CD-R, the main organic dye is the λ of the film.
An organic dye having a max in the range of 750 to 780 nm, and in the case of producing a DVD-R, the main organic dye is an organic dye in which the λmax of the film is in the range of 580 to 630 nm. Further, the inner peripheral portion refers to an area from the inner periphery of the recording area of the optical disc to 2/3 of the radius, and the outer peripheral portion refers to the area from the outer periphery of the recording area of the optical disc to 1/3 of the radius. Therefore, for example, in the case of a DVD-R having a diameter of 120 mm, the radius is 20 mm (corresponding to the inner circumference of the recording area) to the radius 40.
The area up to mm corresponds to the inner circumference, with a radius of 40 mm to a radius of 6
The area up to 0 mm corresponds to the outer peripheral portion.

In any of the optical discs produced, the main organic dye constituting the recording layer is 20% of the recording layer.
It is preferable to occupy 80 wt%. When two or more kinds of organic dyes that function as the main organic dye are contained in the recording layer, at least one kind of the main organic dye is used in the recording layer
If it occupies 0 to 80 wt%, the proportion of the other main organic dyes may be less than 20 wt%. When the proportion of the main organic dye is less than 20 wt%, the optical disc cannot satisfy the modulation degree and jitter defined by the standard. When the proportion of the main organic dye exceeds 80 wt%, the proportion of other organic dyes becomes small, and it becomes difficult to significantly change the reflectance of the optical disc in the radial direction of the disc. The proportion of the main organic dye is preferably changed in the radial direction of the disc so that the proportion is within the range of 20 to 80 wt% in any part of the recording layer.

The type and proportion of the organic dye present at each position in the radial direction of the disc are determined according to how the optical characteristics (specifically, reflectance) of the recording layer are changed in the radial direction of the disc. To be done. As described above, the reflectance of an optical disc formed by using a normal optical disc substrate tends to increase toward the outer peripheral side of the disc. Therefore, when using an ordinary optical disk substrate, it is preferable that the recording layer is formed so that its reflectance is higher in the inner peripheral portion than in the outer peripheral portion.

The reflectance of the recording layer is the λ of the film in the recording layer.
The higher the proportion of the organic pigment having the smaller max, the higher the proportion. Therefore, when the recording layer is formed such that the proportion of the organic dye having a small λmax in the film is larger in the inner peripheral portion than in the outer peripheral portion, the reflectance of the inner peripheral portion of the recording layer is higher than that of the outer peripheral portion. Become. For example, when the recording layer is composed of two kinds of organic dyes, that is, an organic dye A having a small λmax of the film and an organic dye B having a large λmax of the film, A: B
Is preferably 4: 1 to 3: 2 by weight, and A: B in the outer peripheral portion is preferably 1: 4 to 2: 3 by weight.

Each of the organic dyes constituting the recording layer is
OH, -CHO, -COR, -COOH, -COOR,
_{-CONH 2, -CONHR, -CONR 2,} -R, -N
_{H 2, -NO 2, -NHR,} -SO 3 H, -SO 3 M, -
_{X, -CH = CH 2, -OR} , -CN, -SH, -CO
OX, —COOM, —CH ₂ X, —NHSO ₂ R, and —NHSO ₂ Rf (R is an alkyl group or aryl group having 1 to 22 carbon atoms, M is an alkali metal or alkaline earth metal, X is a halogen, Rf Represents a fluoroalkyl group)
It is preferably a compound having at least one group selected from the group consisting of:

At least one group selected from the above group
Among the organic dyes that are compounds having at least one organic dye, at least one type of organic dye is azo, cyanine, phthalocyanine, quinone, indigo, arylmethane, porphine, squarylium, spiropyran, perylene, and It is preferably an organic dye selected from the group consisting of fulgide dyes. Organic dyes selected from this group include 1A group elements (excluding Rb, Cs, and Fr), 2A group elements (excluding Sr and Ra), 3A group elements (excluding Ac), and 4A to 7A group elements. , Group 8 elements, 1
B group element, 2B group element, 3B group element (excluding B), 4B
Group element (excluding C), group 5B element (excluding N, P and Bi), lanthanoid element, and actinoid element (excluding Pu, Cm, Bk, Cf, Es, Fm, Md, No and Lr) More preferably, it is a compound formed by combining at least one metal selected from the group. The compound formed by combining with a metal is, for example, a complex of an azo compound and a metal, a complex of a cyanine compound and a metal, or a complex of a phthalocyanine compound and a metal.

The recording layer is formed by spin coating. In spin coating, a solution in which an organic dye is dissolved in a solvent (also called an organic dye solution) is dropped onto a substrate from a nozzle and applied, and the organic dye solution is cast by rotating the substrate, and then the solvent is evaporated. Is a method of forming a coating film. The organic dye solution has an organic dye concentration of 0.1 to 1 in the solvent.
It is prepared by dissolving it so that it becomes 0 wt%. The solvent is selected in consideration of the solubility of the organic dye. In general, the solvent is selected from alcohol solvents, ketone solvents, ether solvents, pyridine solvents, aniline solvents, amine solvents, piperidine solvents, pyrrolidine solvents, sulfoxide solvents, thiophene solvents and hydrocarbon solvents. To be selected. The solvent may be a mixed solvent. The solvent is 0.1 to 25 ° C.
It is preferable that the viscosity is 50 mPa · s (0.1 to 50 cP).

In order to form the recording layer of the first optical disk of the present invention, the spin coating is carried out by specifically applying organic dye solutions having different organic dye compositions to different positions from the center of the substrate. Dropping is performed from each of the two or more nozzles arranged, and each nozzle is reciprocated in the radial direction of the substrate.

Such spin coating is carried out by a spin coating apparatus as shown in FIG. The spin coater 20 shown in FIG. 2 has two nozzles 22a and 22b arranged at different positions from the center of the substrate 1. The organic dye solution is discharged from the nozzles 22a and 22b. The nozzles 22a and 22b are independent of each other, and their positions can be arbitrarily changed in the radial direction of the substrate. Further, each of the nozzles 22a and 22b is adapted to reciprocate in the radial direction of the substrate during the spin coating, and the illustrated apparatus has a mechanism (not shown) therefor. The substrate 1 is held by the substrate support 24 while the spin coating is performed. The substrate support 24 is connected to a drive device (not shown) so that it can rotate about an axis k. The rotation speed of the substrate support 24 is generally controlled within the range of 50 to 8000 rpm. For easy understanding, the spin coater shown in FIG. 2 is shown such that the ratio of the size of each portion is different from the actual one.

Organic dye solutions having different organic dye compositions are charged into the two nozzles 22a and 22b.
When the organic dye solution is dropped from each nozzle to perform spin coating, the solution dropped from the nozzle 22a is
The recording layer in the region from immediately below a to just below the nozzle 22b is mainly formed, and the solution dropped from the nozzle 22b is
The recording layer in the area from immediately below b to the outer periphery is mainly formed.
Therefore, the composition of the organic dye contained in the organic dye solution dropped from the nozzles 22a and 22b is selected according to the component ratio to be obtained in each region, and the nozzle 22a
By selecting the positions 22 and 22b from the center of the substrate, it is possible to form a recording layer having a desired component ratio in a desired region.

For example, when a recording layer is formed on a substrate having a radius of 60 mm, the nozzle 22a is charged with an organic dye solution having a large compounding ratio of an organic dye having a small λmax, and the nozzle 22b is used.
If an organic dye solution having a large compounding ratio of an organic dye having a large λmax is charged into the nozzle, the nozzle 22a is positioned on the inner circumference of the substrate, and the nozzle 22b is positioned at a radius of 40 to 60 mm on the substrate, the reflectance is on the inner circumference. A recording layer is formed that is high in the portion and low in the outer peripheral portion.

In spin coating, each nozzle is reciprocated in the radial direction of the substrate and the substrate is moved at a low speed (50 to 50).
It is preferable to perform a procedure of dropping a predetermined amount of the organic dye solution from each nozzle while rotating the substrate at 0 rpm), stopping the dropping, and rotating the substrate at a high speed (500 to 8000 rpm). When the nozzle reciprocates in the radial direction, the dropped organic dye solution draws a spiral locus on the substrate surface. When the organic dye solution is dropped in this manner, a thin layer can be formed more uniformly than when the organic dye solution is dropped while the nozzle is stationary. The high-speed rotation of the substrate is performed in order to uniformly spread the organic dye solution on the substrate by the action of centrifugal force and shake off the excess solution. High speed rotation of substrate is generally 1-6
It is carried out for about 0 seconds.

It is preferable that the reciprocating motion of each nozzle is performed such that the nozzle is located on any position in the radial direction of the substrate in the area to be coated by each nozzle. For example, when the area to be coated by the nozzle 22a is the area from the inner circumference of the substrate to the radius rmm, the nozzle 22a is preferably reciprocated between the inner circumference of the substrate and the position of radius rmm.

The amount of the organic dye solution dropped from each nozzle is preferably adjustable independently. The amount of the organic dye solution dropped from each nozzle is selected according to the area of the region to be coated by each nozzle, the wettability, the viscosity and volatilization rate of the solvent, the temperature and humidity of the coating environment, and the like. When using two nozzles as shown in FIG. 2, it is preferable to drop the same amount of the organic dye solution from the inner peripheral side nozzle 22a and the outer peripheral side nozzle 22b, respectively. The organic dye solution is, for example, 0.01 to 0.5c from two nozzles.
It is good to drop by c. The dripping is generally 1-10.
It takes about a second.

Since the illustrated apparatus has two nozzles, the recording layer has two regions having different component ratios. The number of nozzles may be three or more. As the number of nozzles increases, the number of regions having different component ratios in the recording layer can be increased, and the component ratio can be changed in multiple stages. It should be noted that the boundary between regions having different component ratios is not clear regardless of the number of nozzles. This is because a part of the organic dye solution discharged from the nozzle located on the inner peripheral side spreads to the outer peripheral side during the rotation of the substrate.

The illustrated spin coater may have other components or devices included in conventional spin coaters. Other components or devices are, for example, walls that prevent the organic dye solution from splashing around, and drying devices used to evaporate the organic solvent.

Next, the second optical disc of the present invention will be described. In the second optical disc, the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer is not constant in the radial direction of the disc. In the second optical disc, the reflectance of the recording layer is changed in the radial direction of the disc by utilizing the influence of the step between the groove portion and the land portion of the recording layer on the reflectance.
Therefore, in the second optical disc, the recording layer may consist of one type of organic dye. Alternatively, even when the recording layer is composed of two or more kinds of organic dyes, it is not necessary to keep the component ratios constant in the radial direction as in the first optical disc. The organic dye forming the recording layer is selected from those listed as preferable organic dyes in relation to the first optical disc, depending on the type of the optical disc.

In the second optical disc, the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer is changed in the radial direction so that a desired reflectance characteristic can be obtained. Ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer, that is, the thickness t _L / of the land portion of the recording layer
The thickness t _G of the groove portion of the recording layer is preferably in the range of 0.1 to 0.7 in any portion of the recording layer. If it is smaller than 0.1, the reflectance becomes high, but the push-pull signal becomes small and tracking becomes difficult, so that the stability of recording and reproduction is poor.
When it is larger than 0.7, the push-pull signal becomes large, and the stability of recording and reproduction becomes good, but the reflectance becomes low, and the crosstalk of the signal between the grooves becomes large. Poor signal quality.

[0065] In the second optical disc of the present invention, with respect to _t L / _{t G} of the inner peripheral portion of the disc, _t L / _{t G} of the outer periphery of the disc it is preferably differ 5-30%. The ranges of the inner peripheral portion and the outer peripheral portion are as described above in relation to the first optical disc. Perimeter t _L / t
_{When G} does not differ from the inner circumferential portion t _L / t _G by 5% or more, or when it differs by more than 30%,
It may be difficult to make the reflectance uniform on the disk surface.

T _L at each radial position on the disk
/ T _G is determined according to how the optical characteristics (specifically, reflectance) of the recording layer are changed in the radial direction of the disc. As described above, the reflectance of an optical disc formed by using a normal optical disc substrate tends to increase toward the outer peripheral side of the disc. Therefore, when an ordinary optical disk substrate is used, it is preferable to change t _L / t _{G so} that the reflectance of the recording layer is higher in the inner peripheral portion than in the outer peripheral portion.

As described above, the reflectance of the recording layer is t_L/
t_GIs larger, that is, the groove part and the land part
The larger the step between them, the smaller. Therefore, t
_L/ T_GHowever, it is noted that the outer circumference is larger than the inner circumference.
When the recording layer is formed, the reflectance of the inner circumference of the recording layer is
It will be higher than the reflectance. Specifically, t at the outer peripheral portion
_L/ T_GIs preferably 0.35 to 0.7, and
T at the periphery_L/ T _GShould be 0.1 to 0.35
Is preferred. Same type and composition of organic dyes used
If this is the case, generally use a more viscous organic dye solution.
In the recording layer formed by using_L/ T_GIs small
Tends to become. As mentioned above, t_L/ T_GThe size of
It can be known by a shuffle signal.

The recording layer of the second optical disk is also formed by spin coating. The concentration and solvent used when preparing the organic dye solution are as described in relation to the first optical disc, and therefore detailed description thereof is omitted here.

In order to form the recording layer of the second optical disk of the present invention, spin coating was carried out by specifically placing organic dye solutions having different viscosities at different distances from the center of the substrate. Including dropping from each of two or more nozzles. More preferably, spin coating is performed while reciprocating each nozzle in the radial direction of the substrate.

Similar to the first optical disk, such spin coating is also performed by the spin coating apparatus 20 as shown in FIG.
Is carried out using. When manufacturing the second optical disc, the two nozzles 22a and 22b are charged with organic dye solutions having different viscosities. As described in connection with the first optical disc, the two nozzles 22a and 22b
By selecting the position of the substrate from the center of the substrate, a recording layer having a desired t _L / t _G can be formed in a desired region.

The viscosity of the organic dye solution can be changed by changing the kind of the solvent, or by changing the solvent composition when using a mixed solvent in which two or more kinds of solvents are mixed. The viscosity of the organic dye solution dropped from each nozzle depends on the desired t _L in the recording layer after drying.
Choose to obtain / t _G.

In any of the organic dye solutions dropped from any nozzle, the viscosity of the solvent (including mixed solvent) used for preparing the solution is 0.1 to 50 mPa · s (0.
It is preferably in the range of 1 to 50 cP). In general, the lower the viscosity of the solvent is, the lower the boiling point is. Therefore, when the viscosity of the solvent is less than 0.1 mPa · s, the usable time for forming the recording layer is short, that is, the organic dye solution is dropped. It takes less time to evaporate the solvent. Therefore, the solvent may evaporate before the organic dye solution is sufficiently cast, and it may be difficult to form a smooth recording layer. When the viscosity of the solvent exceeds 50 mPa · s, it takes a long time to evaporate the solvent, that is, the recording layer is formed for a long time, so that the entire manufacturing time of the optical disk is lengthened and the manufacturing efficiency is lowered.

When the spin coater as shown in FIG. 2 is used, the viscosity of the solvent contained in the organic dye solution spin-coated on the outer peripheral portion of the disk depends on the organic dye solution spin-coated on the inner peripheral portion of the disk. It is preferable that the viscosity of the solvent contained in is different by 10% or more. Otherwise, t _L / t _G of the recording layer cannot be changed significantly in the radial direction of the disc, and thus the reflectivity of the optical disc does not change significantly in the radial direction of the disc.

Generally, when the same organic dye is used, the higher the viscosity of the solvent, that is, the higher the viscosity of the organic dye solution, the higher the reflectance of the recording layer formed by the solution tends to be. As mentioned above, the optical disk substrate is
Originally, the inner peripheral portion has a low reflectance and the outer peripheral portion has a high reflectance. In order to offset this change in the reflectance of the substrate in the radial direction, it is preferable to make the viscosity of the solvent contained in the organic dye solution dropped on the inner peripheral portion higher than that on the outer peripheral portion. Specifically, the viscosity of the solvent contained in the organic dye solution dropped on the inner peripheral portion is preferably 1.2 to 3 times the viscosity of the solvent contained in the organic dye solution dropped on the outer peripheral portion. As a combination of the solvent contained in the solution dropped on the inner peripheral part / the solvent contained in the solution dropped on the outer peripheral part, specifically, octafluoropentanol (24 mPa ·
s) / tetrafluoropropanol (8 mPa · s),
Dodecafluorohexanol (46 mPa · s) / octafluoropentanol (24 mPa · s), octafluoropentanol (24 mPa · s) / hexafluorobutanol (10 mPa · s) and the like can be mentioned.

The solvent contained in the organic dye solution may be a mixed solvent composed of two or more kinds of solvents having different viscosities. When the solvent is a mixed solvent, the viscosity of the solvent and thus the viscosity of the solution can be changed by changing the compounding ratio of each solvent. When using a mixed solvent, a mixed solvent of 2 to 5 types of solvents having different viscosities is preferably used.
The use of more than 5 kinds of solvent does not change the effect of the present invention of changing the optical characteristics of the recording layer in the radial direction of the disc.

The second optical disc of the present invention is manufactured in the same manner as the first optical disc of the present invention, except that organic dye solutions having different viscosities are used. Therefore, the specific conditions of the spin coating, the specific configuration of the spin coating device, and the like are as described in relation to the first optical disc, and therefore detailed description thereof will be omitted here.

Next, the third optical disc of the present invention will be described. In the third optical disc, the thickness of the reflective layer is not constant in the radial direction of the disc.

The thickness of the reflective layer at each position in the radial direction of the disc takes into consideration the influence of the thickness of the reflective layer on the modulation degree of the optical disc, and how the reflectance of the reflective layer is determined in the radial direction of the disc. It is decided according to whether to change. As described above, when a normal optical disk substrate is used, the reflectance of the optical disk tends to increase toward the outer circumference and the modulation degree tends to decrease toward the outer circumference. Therefore, when using an ordinary optical disk substrate, the thickness of the reflective layer is reduced from the inner circumference to the outer circumference, the reflectance of the reflective layer is decreased from the inner circumference to the outer circumference, and the modulation degree of the optical disk is reduced to the outer circumference. It is preferable to increase it on the side.

In the reflective layer, the thickness of the thinnest portion is
When the thickness of the thickest part is 1, it is preferably less than 0.7. The ratio of the thickness of the thickest part to the thickness of the thinnest part of the reflective layer is more preferably 1 :.
It is 0.7-1: 0.5. When the ratio of the thinnest portion to the thickest portion exceeds 0.7, the reflectance of the reflective layer does not change significantly in the radial direction of the disc. If the ratio of the thinnest part to the thickest part is less than 0.5,
The change of the reflectance becomes too large in the radial direction of the disc, and the reflectance cannot be made uniform in the finally obtained optical disc.

The reflective layer of the third optical disk is made of Ag, A
u, Cu, Al, Pt, Pd, Nd, Mg, Se, Y,
Ti, Zr, Hf, C, N, O, V, Nb, Ta, C
r, Mo, W, Mn, Re, Fe, Co, Ni, Ru,
It is formed of an element selected from the group consisting of Rh, Te, Pb, Sn and Bi. These elements may be used alone or in combination of two or more, for example, in the form of alloy. The elements constituting the reflective layer are selected so that the finally obtained optical disc has a reflectance specified by the standard. For example, in the case of CD-R, the reflective layer is configured such that the entire disc has a reflectance of 65 to 85%, and in the case of DVD-R, the entire disc has a reflectance of 45 to 85%. Therefore, at least one kind of metal element is usually selected as the element constituting the reflectance. The reflective layer is preferably formed of a metal material or alloy containing Ag, Au or Al as a main component. Such metal materials or alloys are preferably used in terms of reflectance and weather resistance. Among them, silver or silver alloy is particularly preferable because it has high reflectance and is advantageous in cost.

The thickness of the reflective layer depends on the type of metal used, the optical characteristics of the recording layer, the type of optical disc, etc.
The finally obtained optical disc is selected so as to satisfy the disc characteristic (for example, jitter) defined by the standard. For example, the reflective layer of the CD-R is made of Au, Ag, Al, or an alloy thereof and has a thickness of 6 at the thickest portion.
It is preferably formed to have a thickness of 0 to 200 nm. C
It is more preferable that the thickness of the reflective layer of D-R is changed within the range of 50 to 170 nm (that is, the thinnest portion does not become thinner than 50 mm and the thickest portion does not become thicker than 170 mm). . The reflective layer of the DVD-R is Au,
It is preferable to use Ag, Al or an alloy thereof so that the thinnest portion has a thickness of 50 nm or more. It is more preferable that the thickness of the reflective layer of the DVD-R varies within the range of 75 to 170 nm.

The reflective layer is formed on the surface of the recording layer by sputtering after the recording layer is formed on the substrate. Sputtering is generally adopted as a method for forming a reflective layer of an optical disc. In forming the reflective layer of the third optical disc, sputtering is performed while the substrate is rotated by placing a shield plate covering a part of the substrate between the target and the substrate, whereby the thickness of the reflective layer is increased. Is not constant in the radial direction of the disc.

The target material does not adhere to the portion of the substrate covered with the shield plate. Therefore, it is necessary to rotate the substrate during sputtering so that a portion where the reflective layer is not formed does not occur on the substrate. Furthermore, the shield plate
It is necessary for the substrate to have a shape such that there is no portion covered with the shielding plate during one rotation of the substrate.
That is, when the substrate is stationary, the shielding plate is such that at least a part of a line (that is, a line that draws a circle) that connects points equidistant from the center of the substrate in the area where the reflective layer is to be formed. It must have a shape so that it cannot be covered with a shield.
This is because if all of the lines that draw a circle are covered with the shielding plate, some portions will not be sputtered even if the substrate is rotated.

The shield plate is arranged so as to be located between the substrate and the target. When the target and the substrate are arranged such that their surfaces are opposed to each other, the shielding plate is preferably arranged near the substrate surface, and the distance between the shielding plate and the substrate surface may be up to about 5 cm. Alternatively, the shield may be placed on the surface of the target. Also,
The shield plate is made of a heat-resistant material (for example, metal such as aluminum or SUS, or plastic such as polycarbonate) that does not deform even at about 100 ° C., and its thickness is preferably about 0.5 to 2 mm.

Sputtering using a shielding plate is performed as shown in FIG.
It is carried out by a sputtering device as shown in FIG. FIG. 3A schematically shows the positional relationship among the target T, the shielding plate S, and the substrate 10 included in the sputtering device 30. 3B and 3C are plan views each showing an example of the shielding plate S. Illustrated sputtering equipment
At 30, the target T is in the form of a disk having the same diameter as the substrate 10, and is arranged such that its surface faces the surface of the substrate and is parallel to the surface of the substrate. A shield plate S is arranged between the target T and the substrate 10. For ease of understanding, the sputtering apparatus of FIG. 3 is illustrated such that the size ratio of each portion is different from the actual one.

The shielding plate S shown in FIG. 3B is a disk-shaped plate having the same diameter as the substrate. The shield plate is formed with two circular openings h1 and h2, each of which has the same diameter as the radius of the substrate, and the diameter of the two openings is equal to the diameter of the shield plate. They are in line with each other. When the shielding plate S shown in FIG. 3B is used, the thickness of the reflective layer decreases from the inner circumference to the outer circumference. The shielding plate shown in FIG. 3 (c) has two disk-shaped plates d having the same diameter as the radius of the substrate.
1 and d2. The diameters of the two plates are aligned with the diameter of the substrate. When the shielding plate shown in FIG. 3C is used, the thickness of the reflective layer increases from the inner circumference to the outer circumference. The shield plate shown is an example, and the shield plate may have another shape as long as the thickness of the reflective layer can be changed as desired in the radial direction of the disc.

Examples of other shielding plates are shown in FIGS.
It shows in (e). Each of the shielding plates S shown in FIG. 5 has an opening h, and when the shielding plate S is positioned between the substrate and the target and sputtering is carried out, the thickness of the reflective layer becomes equal to the shape size and number of the openings h. Accordingly, it changes in the radial direction of the disc. When the shielding plate of (a) to (d) of FIG. 5 is used, the thickness of the reflective layer decreases from the inner periphery to the outer periphery, and when the shielding plate of (e) of FIG. 5 is used, the thickness of the reflective layer is reduced. The depth increases from the inner circumference to the outer circumference. In the shielding plate of FIG. 5C, the greater the bulge near the center of the opening h, the greater the difference between the thickness of the reflective layer on the inner circumference and the thickness of the reflective layer on the outer circumference. When a shielding plate having openings as shown in FIG. 5 is used, the shape and number of the openings are occupied on a line (that is, a line that draws a circle) that connects points equidistant from the center of the substrate. The thickness of the reflective layer can be changed as desired in the radial direction of the disk by appropriately selecting the ratio of the parts from the inner circumference to the outer circumference. For example, if the ratio of the openings occupying the line connecting the points equidistant from the center of the substrate decreases from the inner circumference to the outer circumference, the thickness of the reflective layer decreases from the inner circumference to the outer circumference.

In the sputtering using the apparatus shown in the drawing, the substrate support 32 is rotated about the axis n by a driving device (not shown) to rotate the substrate 10, and the metal is sputtered and evaporated from the surface of the target T. Let this be the substrate
It is carried out by attaching to 10 surfaces. Sputter evaporation is carried out in a conventional manner and may be carried out, for example, by glow discharge with the target as cathode or by ion beam. The sputtering conditions may be the conditions adopted when forming the reflective layer of the optical disc.

FIG. 3 shows an outline of an example of a sputtering apparatus suitable for manufacturing a third optical disk. The sputtering apparatus may include other members or devices included in a conventional sputtering apparatus, such as a power supply and an exhaust device. Also, the target may not have the same diameter as the substrate.

Next explained is the fourth optical disc of the invention. In the fourth optical disc, the reflective layer contains two or more kinds of elements as constituent components, and the component ratio in the reflective layer is not constant in the radial direction of the disc. The element is selected from those adopted as an element constituting the reflective layer of the optical disc, and is, for example, a metal element.

The elements constituting the reflective layer are elements having different reflectances. Elements with different reflectances are
The absorption amount of light of the recording / reproducing wavelength is different. When a reflective layer is formed of two or more kinds of elements having different reflectances and irradiated with light having a recording / reproducing wavelength, a reflective layer formed of one kind of element is formed according to the ratio of each element in the reflective layer. It shows different reflectivities. Therefore, the reflective layer in which the component ratio in the reflective layer is not constant in the radial direction of the disc exhibits different reflectance in the radial direction of the disc depending on the component ratio.

The reflective layer is preferably formed of a silver alloy as described above. When the reflective layer of the fourth optical disc is made of a silver alloy, the components other than silver are 0.5 to 10 wt% of the total.
% Is preferable. Further, the component ratio in the reflective layer is preferably changed in the radial direction of the disc so that the ratio of components other than silver is within this range in any part of the reflective layer.

The silver alloy contains Au, C as components other than silver.
u, Al, Pt, Pd, Nd, Mg, Se, Y, Ti,
Zr, Hf, C, N, O, V, Nb, Ta, Cr, M
o, W, Mn, Re, Fe, Co, Ni, Ru, Rh,
Preferably, it contains at least one element selected from the group consisting of Te, Pb, Sn and Bi,
More preferably, it is an Ag-Au-Nd alloy or an Ag-Pd-Cu alloy.

When a silver alloy is used, the proportion of components other than silver occupied at each position in the radial direction of the disk is determined according to how the reflectance of the reflective layer is changed in the radial direction of the disk. It The reflectance of a silver alloy decreases as the proportion of components other than silver increases. As described above, the reflectance of an optical disc formed by using a normal optical disc substrate tends to increase toward the outer peripheral side of the disc. Therefore, when an ordinary optical disk substrate is used, it is preferable to increase the proportion of components other than silver from the inner circumference to the outer circumference and decrease the reflectance of the reflective layer from the inner circumference to the outer circumference.

When the proportion of the components other than silver is increased from the inner circumference to the outer circumference, the proportion of the components other than silver on the outer circumference of the disc is larger than the proportion of the components other than silver on the inner circumference of the disc. 10% or more is preferable, and 1
More preferably, it is larger by 50%. Therefore, for example, the ratio of components other than silver on the inner circumference of the disk is 5w.
When it is t%, the ratio of components other than silver on the outer periphery of the disk is preferably 5.5 wt% or more, and more preferably 5.5 to 7.5 wt%. The reflectance of the optical disc does not change significantly in the radial direction of the disc when the ratio of the components other than silver occupying the inner periphery and the outer periphery of the disc does not differ by 10% or more.

The reflective layer of the fourth optical disk may be made of a material other than a silver alloy, for example, an alloy containing Au or Al as a main component. Also, the reflective layer is 2
As long as it is composed of more than one kind of element, it may be formed of any material, and is not necessarily formed of an alloy.

The thickness of the reflective layer of the fourth optical disc is a disc for which the finally obtained optical disc is defined by a standard according to the type of element used, the optical characteristics of the recording layer, the type of optical disc, and the like. It is selected so as to satisfy the characteristic (eg, jitter). For example, a reflective layer of CD-R,
When aluminum is formed as the main constituent, its thickness is preferably 70-100 nm. DVD
When the -R reflective layer is formed with silver as a main constituent, the thickness thereof is preferably 50 nm or more.

The reflective layer of the fourth optical disk is also formed by sputtering. Sputtering is performed by using a plurality of independent targets having different compositions, sequentially moving the substrate, and performing sputtering with each target. Further, when sputtering with at least one target, the sputtering is performed between the target and the substrate. A shielding plate that covers a part is arranged and the substrate is rotated. If sputtering is performed in this manner, the component ratio in the reflective layer will not be constant in the radial direction of the disc.

FIG. 4 shows a sputtering apparatus 40 suitable for carrying out the above-mentioned sputtering. Figure 4 (a)
Shows schematically the positional relationship among the targets Ta to Tc, the shielding plates Sa and Sb, and the substrate 10. FIG. 4B
[FIG. 6] is a plan view showing a positional relationship between each of the targets Ta to Tc and the shielding plates Sa and Sb as viewed from the substrate side. For ease of understanding, the sputtering apparatus of FIG. 4 is shown such that the size ratio of each portion is different from the actual one.

In the illustrated sputtering apparatus,
Three targets Ta, Tb and Tc having different compositions are arranged. Both targets are disk-shaped with the same diameter as the substrate. The substrate 10 is attached to a rotatable substrate support 42, the substrate support 42 is attached to a turntable 44, and the turntable 44 is fixed to a support 46. The turntable 44 rotates as the support 46 rotates about the axis n1, and the substrate 10 revolves around it, thus drawing a locus indicated by a broken line in FIG. 4B. The substrate 10 is also
The substrate support 42 rotates about the axis n2 to rotate on its axis.

While the substrate 10 revolves, the substrate 10 faces each of the targets Ta to Tc. Substrate 10 is sputtered on each target when facing each target. At this time, other targets do not participate in the thin film formation. In the illustrated apparatus, sputtering is repeatedly performed using targets Ta, Tb, and Tc in this order. As a result, the reflective layer has a structure in which thin films derived from each target are repeatedly formed in the order of Ta film-Tb film-Tc film.

The substrate 10 is revolved so as to be stationary for about 5 to 10 seconds when the substrate faces each target. Therefore, the driving device for rotating the support base 46 needs to have a function of quickly stopping the rotation when the substrate 10 faces the target. The support 46 is rotated when moving the substrate 10 from one target to the next. At this time, from the viewpoint of manufacturing efficiency, it is preferable that the moving time of the substrate 10 be as short as possible.
It is preferable that the substrate 10 is moved by rotating 46 at a high rotation speed. However, if the rotation speed is set too high, the substrate 10
It becomes difficult to immediately stop at a position facing the target. The rotation speed of the support base 46 is specifically 200 r
It is preferably up to about pm.

In the illustrated sputtering apparatus 40,
Above the two targets Ta and Tb, the shield S
a and Sb are arranged. The shield plate Sa has the same shape as the shield plate shown in FIG. Therefore, when sputtering with the target Ta, a film whose thickness increases from the inner circumference to the outer circumference is obtained. Shield S
b has the same shape as the shielding plate shown in FIG. Therefore, when sputtering with the target Tb, a film with a reduced thickness from the inner circumference to the outer circumference is obtained. Further, the shapes and dimensions of the openings hb ₁ and hb ₂ formed in the shield plate Sb are the same as those of the disk-shaped plates da ₁ and da ₂ that form the shield plate Sa.
No shielding plate is arranged on the surface of the target Tc.
Therefore, when sputtering with the target Tc,
A film having a uniform thickness can be obtained.

When sputtering with the targets Ta and Tb, the substrate 10 needs to rotate. The board is
The substrate support 42 is rotated about its axis by rotation of the shaft. Board 10
Is rotated at a rotation speed of 30 to 100 rpm, for example.
When sputtering with Tc, because there is no shield,
The substrate does not have to rotate.

Using this sputtering apparatus, a reflective layer made of a silver alloy, in which the proportion of components other than silver decreases from the inner circumference to the outer circumference, is formed as follows.
As a target, three types of silver alloys having different proportions of components other than silver are used. Of the three targets, the target with the largest proportion of components other than silver is Ta.
And the smallest one is Tc, and FIG.
Place it like.

First, sputtering is performed with the substrate facing the target Ta. As described above, the thickness of the thin film formed by sputtering using the target Ta increases from the inner circumference to the outer circumference in the radial direction of the disk. Next, the substrate is opposed to the target Tb and sputtering is performed. As described above, the thickness of the thin film formed by sputtering using the target Tb decreases from the inner circumference to the outer circumference in the radial direction of the disk. Next, sputtering is performed with the substrate facing the target Tc. Since no shielding plate is arranged between the target Tc and the substrate, the thickness of the thin film formed by sputtering using the target Tc is constant.

Two openings hb ₁ and hb of the shielding plate Sb
b ₂ is the two plates da ₁ and da constituting the shielding plate Sa
_Since it has the same shape and dimensions as those of 2, the target Ta
The changes in the thickness of the thin film formed by sputtering Tb and Tb cancel each other out. Therefore, the reflective layer formed by this device is a film having a uniform thickness as a whole. In addition, the reflective layer formed by this device has Ta and Tb on a film having a constant thickness derived from Tc.
It can be considered that a film derived from is formed. A film that can be regarded as such has a large proportion of the film derived from the target Ta in the thickness direction in the outer circumference and a large proportion of the film derived from the target Tb in the thickness direction in the inner circumference. Therefore, this reflection layer becomes a reflection layer in which the proportion of components other than silver gradually decreases from the inner circumference to the outer circumference in the radial direction of the disc. The reflective layer actually formed has a multi-layer structure in which a three-layer laminated body in which films derived from Ta to Tc are laminated in this order is repeatedly formed.

The illustrated sputtering apparatus schematically shows an example of an apparatus for forming the reflection layer of the fourth optical disc of the present invention, and the sputtering apparatus included in the optical disc manufacturing apparatus of the present invention is not limited to this. . The sputtering apparatus may have, for example, four targets. Further, the shape of the shielding plate is not limited to that shown in the figure, and may be another shape. The sputtering apparatus may include other members or devices included in a conventional sputtering apparatus, such as a power supply and an exhaust device.

In the illustrated sputtering apparatus, by using only two of the targets Ta to Tc, it is possible to form a reflective layer whose component ratio is not constant in the radial direction of the disk. For example, target T
The reflective layer formed by sputtering of b and Tc can be regarded as a film derived from Tb formed on a film derived from Tc. As described above, the film derived from Tc has a constant thickness, and the film derived from Tb is a film whose thickness decreases from the inner circumference to the outer circumference in the radial direction of the disc. Therefore, the thickness of the entire reflective layer decreases in the radial direction from the inner circumference to the outer circumference. It can also be said that the ratio of the silver alloy having a small silver ratio in the film thickness in the reflective layer is small from the inner circumference to the outer circumference in the radial direction of the disk.
Therefore, in this reflective layer, the thickness of the film decreases from the inner circumference to the outer circumference in the radial direction of the disk, and the proportion of silver decreases from the inner circumference to the outer circumference.

When the sputtering apparatus shown in the figure is used to perform sputtering only with the target Ta or Tb without rotating the rotary table 44, a reflective layer having a constant component ratio and a thickness varied in the radial direction is formed. An optical disc including such a reflective layer corresponds to the above-mentioned third optical disc of the present invention. If the sputtering is performed only with the target Tc, a reflective layer having a constant component ratio and a constant thickness is formed.

Alternatively, the reflective layer of the fourth optical disk is
It is also manufactured by using a disk-shaped target having the same diameter as the substrate, the target of which has a non-uniform radial composition. An example of such a target is shown in FIG. FIG. 6 shows a target Td in which portions having different compositions are concentrically divided into three regions α, β, γ. For example, when the target Td is made of a silver alloy and the proportions of the components other than silver are the largest in the region α and the smallest in the region γ, the proportions of the components other than silver are from the inner circumference to the outer circumference of the disc. An increasing number of reflective layers are formed. The target Td can be arranged in place of the target Tc in the sputtering device shown in FIG. 4, for example. In that case, if the sputtering is performed only with the target Td without rotating the turntable 44, the reflection layer of the fourth optical disc can be formed.

The recording layer or the reflective layer, which is a characteristic part of the first to fourth optical discs of the present invention, has been described above in detail.
The other elements constituting the optical disc of the present invention can be constituted by the materials and methods conventionally adopted, and the overall constitution is the same as the conventional one. Therefore, when the optical disc is, for example, a DVD-R, its configuration is as shown in FIG. 1 described above.

The DVD-R shown in FIG. 1 is the same as the transparent plastic substrate 1 having the groove 1a, the recording layer 2, the reflective layer 3, the adhesive layer 4, and the substrate 1 as described in the section of the prior art. It is configured to include a plastic substrate 5 having a thickness.

The substrate 1 has a thickness of about 0.6 mm and has a structure in which the tracking groove 1a is spirally formed. The substrate 1 is preferably made of a transparent material that allows laser light to pass through well. Examples of such a material include polycarbonate resin. The groove 1a has a depth of 150 to 180 nm and a groove width of 0.2.
It is formed to have a thickness of 3 to 0.37 μm, and its track pitch is 0.74 μm.

The recording layer 2 and the reflective layer 3 are as described above. In the illustrated embodiment, the substrate 5 is laminated on the reflective layer 3 with the adhesive layer 4 interposed therebetween. The substrate 5 is provided to increase the overall strength. The substrate 5 preferably has the same thickness as the substrate 1 and is made of the same material as the substrate 1. The adhesive layer 4 is formed by applying an epoxy resin, a urethane resin, an acrylic resin, a silicone resin, or the like, which is cured by ultraviolet rays, onto the reflective layer 3 by a method such as spin coating or spraying. Instead of the substrate 5, the adhesive layer 4 has a layer thickness of 0.57 to
Coating to form a protective layer of about 0.63 mm,
This may improve the overall strength.

[0116]

EXAMPLES Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the invention.

(Synthesis of Organic Dye) Two kinds of azo dyes represented by the following chemical formulas (1) and (2) were prepared as organic dyes constituting the recording layer.

[0118]

[Chemical 1]

[0119]

[Chemical 2]

The azo dye represented by the chemical formula (1) was synthesized according to the following procedure. 1) 2- (5-methyl-1,3,4-thiadiazolyl-
Synthesis of 2-azo) -5- (diethylamino) -N- (trifluoromethanesulfonyl) aniline In a reaction vessel, acetic acid 70 ml, propionic acid 35 ml, 2
-Amino-1,3,4-thiadiazole (8.0 g) and 62% sulfuric acid (7 ml) were charged, the mixture was cooled to 0 ° C with stirring, and 44% nitrosyl sulfuric acid (24.1 g) was added dropwise thereto over 1 hour (liquid A). And). In a separate container, 3- (diethylamino) -N- (trifluoromethanesulfonyl)
Aniline trifluoromethanesulfonate 37.2
g, 200 ml of methanol, 2.9 g of urea, and 28 g of sodium acetate were charged, and the mixture was cooled to 0 ° C. with stirring. After the above liquid A was added dropwise to this over 1 hour, cooling was stopped and the temperature was gradually returned to room temperature, followed by stirring overnight. Water 3 in the reaction solution
After adding 0 ml dropwise, the reaction solution was filtered to obtain crystals. This was washed with warm water and methanol and then dried to obtain 11 g of crystals of the azo compound.

2) Bis [2- (5-methyl-1,3,4)
-Thiadiazolyl-2-azo) -5- (diethylamino) -N- (trifluoromethanesulfonyl) anilinato] nickel synthesis 11 g of the azo compound obtained in 1) and 85 ml of methanol were mixed and heated to 50 ° C with stirring. did. To this heated mixture, 3.5 g of nickel acetate tetrahydrate was added little by little. After stirring at 50-60 ° C for 3 hours, the mixture was allowed to cool and filtered. The obtained crystals are washed with warm water and methanol in that order, and dried to give the complex 1 represented by the chemical formula (1).
1.4 g was obtained.

The azo dye represented by the chemical formula (2) was synthesized according to the following procedure. 1) 2- (5-methyl-3-isoxazolylazo) -4
Synthesis of -ethoxy-5- (diethylamino) -N- (trifluoromethanesulfonyl) aniline In a reaction vessel, 0.5 g of 3-amino-5-methylisoxazole, 5.1 ml of acetic acid, 2.6 ml of propionic acid,
And 0.5% of 62% sulfuric acid were charged, cooled to 0 ° C.,
To this, 1.8 g of 44% nitrosylsulfuric acid was added dropwise over 20 minutes (referred to as solution A). In a separate container, the trifluoromethanesulfonate salt of 3- (diethylamino) -4-ethoxy-N- (trifluoromethanesulfonyl) aniline.2.
8 g, 1.3 g of sodium acetate, 0.13 g of urea, and 15 ml of methanol were charged, and the mixture was cooled to 0 ° C. with stirring. The solution A was added dropwise to the solution over 30 minutes, and the solution was stirred for additional 2 hours. The crystals were washed with warm water and then recrystallized from methanol to obtain 0.87 g of an azo compound.

2) Synthesis of bis [2- (5-methyl-3-isoxazolylazo) -4-ethoxy-5- (diethylamino) -N- (trifluoromethanesulfonyl) anilinato] nickel 1) Azo compound 0.87g and methanol 9ml
And were mixed, and the temperature was raised to 50 ° C. To this heated mixture was added 0.24 g of nickel acetate tetrahydrate. 50-
After stirring at 60 ° C. for 2 hours, the mixture was allowed to cool and the reaction solution was filtered. The obtained crystals are washed successively with hot water and methanol and then dried to give a complex of the chemical formula (2) 0.75
g was obtained.

The azo dye represented by the chemical formula (1) (also referred to as "azo dye (1)") has a film λmax of 605 nm.
The azo dye represented by the chemical formula (2) (also referred to as “azo dye (2)”) has a film λmax of 592 nm. Therefore, any of the azo dyes alone
The recording layer of VD-R can be formed. In addition, all of the azo dyes were added to 100 ml of tetrafluoropropanol with 5
It can dissolve more than g.

(Sample 1) A DVD-R having the structure shown in FIG. 1 in which the component ratio in the recording layer was not constant in the radial direction of the disc was produced by the following procedure. As the substrate 1, a doughnut-shaped substrate made of a polycarbonate resin having an inner diameter of 15 mm, an outer diameter of 120 mm and a thickness of 0.6 mm was prepared. This substrate has a spiral groove 1a on one surface and a groove depth of 160-18.
0 nm, groove width 0.25 μm, track pitch 0.74
was μm.

On the surface of the substrate 1 where the groove 1a is formed,
The recording layer 2 was formed. The recording layer 2 was formed using the spin coater shown in FIG. The organic dye solution charged in the nozzle 22a is an azo dye (1) and an azo dye (2).
Were mixed in a weight ratio of 20:80, and this was dissolved in tetrafluoropropanol to prepare the solution. The organic dye solution charged into the nozzle 22b was prepared by mixing the azo dye (1) and the azo dye (2) at a weight ratio of 80:20 and dissolving the mixture in tetrafluoropropanol. The concentration of the dye in each of the organic dye solutions was 1 wt%. Further, the organic dye solution was filtered with a 0.2 μm filter paper before being charged into the nozzle.

These organic dye solutions were dropped from the nozzle 22a and the nozzle 22b, respectively, and applied to the surface of the substrate 1. At this time, the nozzle 22a is reciprocally moved in the radial direction of the substrate 1 from the inner circumference of the substrate 1 to a position having a radius of 40 mm, and the nozzle 22b is moved from the position having a radius of 40 mm to the outer periphery in the radial direction of the substrate 1. It was reciprocated between. Each organic dye solution is 0.015 from the nozzle 22a.
g, 0.015 g from the nozzle 22b, and was dripped over 1.5 seconds. During the dropping of the organic dye solution, the substrate 1 is 240 rpm
I rotated it. After dropping, the rotation speed of the substrate 1 is 3500 rp
The substrate 1 was rotated for about 15 seconds while gradually increasing to m to uniformly cast the organic dye solution and shake off the excess solution. The rotation of the substrate 1 was performed by rotating the substrate support base 24 by a drive device (motor).
Finally, the solvent in the organic dye solution was evaporated to obtain a recording layer 2 having a thickness of about 120 nm in the groove 1a.

In the recording layer 2, the ratio of the organic dye having a small λmax (that is, a high reflectance) is large in the region from the inner circumference of the disc to the radius of 40 mm, and the radius of 40 mm.
In the region from mm to the outer circumference, the proportion of the organic dye having a large λmax (that is, a low reflectance) was large.

Then, the reflective layer 3 was formed on the recording layer 2 by sputtering. The sputtering was performed using the sputtering apparatus shown in FIG. 4 and using only the target Tc. Therefore, the reflective layer 3 was formed to have a uniform thickness and composition ratio over the entire substrate. As a target Tc, a silver alloy (Ag 98 wt%
(Above) was used. The thickness of the reflective layer 3 was 120 nm.

Next, a polycarbonate resin substrate 5 having the same shape and size as the substrate 1 (however, no groove was formed) was laminated on the reflective layer 3 with an adhesive layer 4 interposed therebetween. The procedure is as follows. First, on one surface of the substrate 5, as the adhesive layer 4, a UV curable polyurethane acrylate resin (trade name; SD-301, manufactured by Dainippon Ink and Chemicals, Inc.)
Was applied by spin coating to a thickness of 40 to 60 μm. Next, the substrate 5 was laminated on the reflective layer 3 so that the adhesive layer 4 and the reflective layer 3 were in contact with each other. Then, the substrate 5 was fixed by irradiating ultraviolet rays to cure the adhesive layer 4, and a DVD-R was obtained.

(Sample 2) A DVD-R having the structure shown in FIG. 1 in which t _L / t _G of the recording layer was not constant in the radial direction of the disc was produced by the following procedure. As the substrate 1, the same substrate as that used for producing the sample 1 was prepared, and the recording layer 2 was formed on the surface on which the groove 1a was formed.
Was formed. The recording layer 2 was formed using the spin coater shown in FIG. The organic dye solution charged into the nozzle 22a was prepared by mixing the azo dye (1) and the azo dye (2) at a weight ratio of 50:50, and adding this to octafluoropentanol (viscosity at 25 ° C .: 24 mPa · s). It was prepared by dissolving. The dye concentration was 1.5 wt%. nozzle
The organic dye solution charged to 22b was prepared by mixing the azo dye (1) and the azo dye (2) at a weight ratio of 50:50, and mixing the mixture with tetrafluoropropanol (viscosity at 25 ° C .:
It was prepared by dissolving in 8 mPa · s). The dye concentration is 1.
It was set to 0 wt%. In addition, each dye solution was filtered with 0.2 μm filter paper before being charged into the nozzle.

These organic dye solutions were dropped from nozzles 22a and 22b in the same manner as in Sample 1 and cast,
The solvent was evaporated to obtain Recording Layer 2. In the recording layer 2, the thickness of the portion in the groove 1a is about 120 nm, and the thickness t _L of the land portion / the thickness t _{G of the} groove portion is about 0. 3 and about 0.5, which varied in the radial direction.

Further, after the reflective layer 3 was formed in the same manner as the sample 1, the substrate 5 was laminated with the adhesive layer 4 interposed therebetween. The adhesive layer 4 is hardened, the substrate 5 is fixed, and the DVD-R
Got

(Sample 3) A DVD-R having the structure shown in FIG. 1 in which the thickness of the reflection layer was not constant in the radial direction of the disc was produced by the following procedure. As the substrate 1, the same substrate as that used for producing the sample 1 was prepared, and the recording layer 2 was formed on the surface on which the groove 1a was formed. The recording layer 2 is a solution prepared by dissolving the azo dye (1) in tetrafluoropropanol (dye concentration 1 wt.
%) Was used for spin coating. The recording layer 2 of Sample 3 was formed by dropping an organic dye solution from one nozzle using a normal spin coater. Also,
The recording layer 2 has a thickness of about 120 nm in the groove 1a.
Was formed so that

Then, the reflective layer 3 was formed on the recording layer 2 by sputtering. Sputtering was performed using the sputtering apparatus shown in FIG. 4 and using only the target Tb. Therefore, the reflective layer 3 was formed so that the component ratio was constant in the radial direction of the disk and the thickness thereof decreased from the inner circumference to the outer circumference. A silver alloy (Ag 98 wt% or more) was used as the target Ta. The thickness of the reflective layer 3 was 160 nm on the inner circumference and 80 nm on the outer circumference.

Next, the substrate 5 was laminated with the adhesive layer 4 interposed therebetween in the same procedure as when the sample 1 was manufactured, and a DVD-R was obtained.

(Sample 4) A DVD-R having the structure shown in FIG. 1 in which the component ratio in the reflective layer was not constant in the radial direction of the disc was produced by the following procedure. As the substrate 1, the same substrate as that used for producing the sample 1 was prepared, and the recording layer 2 was formed on the surface on which the groove 1a was formed.
Was formed. The recording layer 2 was formed by the same procedure as when the sample 3 was manufactured.

Next, the reflective layer 3 was formed on the recording layer 2 by sputtering. Sputtering uses the sputtering device shown in FIG. 4, and targets Ta-Tc are used.
In order to repeatedly perform sputtering.
The target Ta is Ag: Au: Nd = 85: 10: 5.
(Weight ratio) of a silver alloy, and the target Tb is Ag: A
The silver alloy of u: Nd = 93: 5: 2 (weight ratio) was used, and the target Tc was a silver alloy of Ag = 98 wt% or more. Shielding plates Sa and Sb shown in FIG. 4B are arranged on the surfaces of the targets Ta and Tb, respectively. The sputtering was performed by rotating the substrate support 42 so that each target and the substrate face each other for 10 seconds. When moving the substrate between the targets, the substrate support 42 is moved to 4
It was rotated at 0 rpm. During the sputtering, the support base 46 was rotated at 10 rpm to rotate the substrate. In the obtained reflective layer 3, the proportion of highly reflective silver gradually decreased from the inner circumference to the outer circumference. The thickness of the reflective layer 3 is 1
It was set to 20 nm.

Then, the substrate 5 was laminated with the adhesive layer 4 interposed therebetween in the same procedure as when the sample 1 was manufactured, and a DVD-R was obtained.

(Sample 5: Comparative Sample) D of the structure shown in FIG.
A DVD-R, which is a VD-R and in which the component ratio in the recording layer, the thickness of the reflective layer, and the component ratio in the reflective layer are all constant in the radial direction of the disc, was manufactured as follows.

As the substrate 1, the same substrate as used in the preparation of the sample 1 was prepared, and the surface on which the groove 1a was formed was
The recording layer 2 was formed. The recording layer 2 was formed by the same procedure as when the sample 3 was manufactured. Then, on the recording layer 2,
The reflective layer 3 was formed by the same procedure as when the sample 1 was manufactured. Further, the substrate 5 is laminated on the reflective layer 3 with the adhesive layer 4 interposed therebetween in the same procedure as in the case of producing the sample 1.
DVD-R was obtained.

Table 1 shows the configurations of the disks of Samples 1 to 5 produced.

[0143]

[Table 1]

The disk characteristics were evaluated by measuring the reflectance and modulation of each of Samples 1-5. The reflectance and the degree of modulation are
It was measured with an optical disk evaluation device (DDU-1000, manufactured by Pulstec Industrial Co., Ltd.). Wavelength of 650
It was carried out using a laser beam of nm. Disc characteristics are 25 mm radius, 40 mm radius, and 55 mm radius
The maximum value and the minimum value were obtained by measuring the reflectance and the degree of modulation at the position of, and the change amount, which is the difference between these two values, was evaluated. The evaluation results are shown in Table 2.

[0145]

[Table 2]

From Table 2, the optical disc (Sample 5) in which the recording layer is composed of one kind of organic dye, and the film thickness of the reflective layer and the component ratio in the reflective layer do not change in the radial direction of the disc (Sample 5), The amount of change was large. On the other hand, Samples 1 to 4 had small changes in reflectance and modulation in the radial direction of the disk and had stable disk characteristics.

[0147]

According to the optical disk of the present invention, at least the component ratio of the organic dye in the recording layer, the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer, the thickness of the reflecting layer, and the component ratio of the reflecting layer are at least. One is characterized in that it is not constant in the radial direction of the disk.
According to this feature, even when using an inexpensive substrate in which the birefringence and / or the depth of the groove are not constant in the radial direction of the disc, it is possible to reduce the amount of change in the reflectance and the degree of modulation within the disc surface. Becomes Therefore, according to the present invention, it becomes possible to manufacture a high-quality optical disc at low cost.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of an optical disc of the present invention.

FIG. 2 is a schematic view of a spin coater included in the optical disc manufacturing apparatus of the present invention.

FIG. 3A is a schematic view of a sputtering apparatus included in the optical disk manufacturing apparatus of the present invention, and FIG.
And (c) are plan views of the shielding plate.

FIG. 4A is a schematic view of a sputtering apparatus included in the optical disk manufacturing apparatus of the present invention, and FIG.
FIG. 4 is a plan view of a target and a shield plate.

5 (a) to 5 (e) are plan views of a shielding plate used in a sputtering apparatus included in the optical disk manufacturing apparatus of the present invention.

FIG. 6 is a plan view of a target used in a sputtering apparatus included in the optical disk manufacturing apparatus of the present invention.

[Explanation of symbols]

1 ... Substrate, 1a ... Groove, 2 ... Recording layer, 3 ... Reflective layer, 4 ... Adhesive layer, 5 ... Substrate, 10 ... Substrate, 20 ...
Spin coater, 22a, 22b ... Nozzle, 24 ...
Substrate support, 30, 40 ... Sputtering equipment, 3
2, 42 ... substrate support base, 46 ... support base, 44 ... rotary base, T, Ta, Tb, Tc, Td ... target, S,
Sa, Sb ... shielding _{plate, h1, h2, hb 1,} hb 2,
h ... _{opening, d1, d2, da 1,} da 2 ... disk-shaped plate.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/26 531 B41M 5/26 Y (72) Inventor Yu Oda Kiryu 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Sangyo Co., Ltd. F-term (reference) 2H111 EA03 EA12 EA22 EA25 EA37 FA01 FA12 FA23 FB42 FB43 FB45 FB46 FB48 GA02 GA07 5D029 JA04 JB36 JB37 MA13 MA14 5D121 AA01 AA05 EE03 EE09 EE11 EE20 EE22 EE24 EE22 EE24 EE22

Claims (21)

[Claims] 1. An optical disc having a recording layer made of an organic dye, wherein the recording layer contains two or more kinds of organic dyes as constituent components, and the component ratio in the recording layer is not constant in the radial direction of the disc. Optical disc. 2. The optical disc according to claim 1, wherein the proportion of the main organic dye in the outer peripheral portion of the disc is 10% or more different from the proportion of the main organic pigment in the inner peripheral portion of the disc. 3. An optical disc having a recording layer made of an organic dye, wherein the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer is not constant in the radial direction of the disc. 4. The optical disk according to claim 3, wherein the ratio of the thickness of the land portion to the thickness of the groove portion of the recording layer increases from the inner circumference to the outer circumference of the disk. 5. The organic dye is --OH, --CHO, --CO.
_{R, -COOH, -COOR, -CONH 2} , -CON
_{HR, -CONR 2, -R, -NH} 2, -NO 2, -NH
_{R, -SO 3 H, -SO 3} M, -X, -CH = CH 2, -
OR, -CN, -SH, -COOX, -COOM, -C
H ₂ X, —NHSO ₂ R, and —NHSO ₂ Rf (R is an alkyl group or aryl group having 1 to 22 carbon atoms, M is an alkali metal or alkaline earth metal, X is a halogen, Rf
Is a compound having a group selected from the group consisting of (indicating a fluoroalkyl group). 5. The optical disc according to claim 1, wherein 6. Among the organic dyes which are compounds having a group selected from the above group, at least one type of organic dye is azo, cyanine, phthalocyanine, quinone, indigo, arylmethane, The optical disk according to claim 5, which is selected from the group consisting of porphine-based dyes, squarylium-based dyes, spiropyran-based dyes, perylene-based dyes, and fulgide-based dyes. 7. At least one organic dye selected from the group of dyes is a Group 1A element (excluding Rb, Cs and Fr), a Group 2A element (excluding Sr and Ra),
3A group element (excluding Ac), 4A to 7A group element, 8 group element, 1B group element, 2B group element, 3B group element (excluding B), 4B group element (excluding C), 5B group element (N , P and Bi), lanthanoid elements, and actinide elements (Pu, Cm, Bk, Cf, Es, Fm, M
The optical disc according to claim 6, which is a compound formed by combining at least one metal selected from the group consisting of d, No and Lr). 8. An optical disc having a recording layer made of an organic dye and a reflective layer, wherein the thickness of the reflective layer is not constant in the radial direction of the disc. 9. The optical disc according to claim 8, wherein the thickness of the reflective layer decreases from the inner periphery of the disc toward the outer periphery thereof. 10. The ratio of the thickness of the thickest portion to the thickness of the thinnest portion of the reflective layer is 1: 0.7 to 1: 0.
The optical disc according to claim 8 or 9, which is No. 5. 11. An optical disc having a recording layer made of an organic dye and a reflection layer, wherein the reflection layer contains two or more kinds of elements as constituent components, and the component ratio in the reflection layer is not constant in the radial direction of the disc. An optical disc characterized by. 12. The reflection layer is made of a silver alloy in which the proportion of components other than silver is 0.5 to 10 wt%.
The optical disc described in. 13. The optical disc according to claim 12, wherein the proportion of components other than silver increases from the inner circumference to the outer circumference of the disc. 14. The optical disk according to claim 12, wherein the ratio of the components other than silver on the outer periphery of the disc is 10% or more higher than the ratio of the components other than silver on the inner periphery of the disc. 15. A silver alloy containing A as a component other than silver.
u, Cu, Al, Pt, Pd, Nd, Mg, Se, Y,
Ti, Zr, Hf, C, N, O, V, Nb, Ta, C
r, Mo, W, Mn, Re, Fe, Co, Ni, Ru,
The optical disc according to any one of claims 12 to 14, which contains at least one element selected from the group consisting of Rh, Te, Pb, Sn, and Bi. 16. The method of manufacturing an optical disc according to claim 1, comprising forming the recording layer by spin coating with an organic dye solution, the spin coating being provided at different positions from the center of the substrate. A method for manufacturing an optical disk, characterized in that organic dye solutions having different organic dye compositions are dropped from two or more nozzles arranged and each nozzle is reciprocated in the radial direction of the substrate. 17. The method for manufacturing an optical disc according to claim 3, comprising forming the recording layer by spin coating with an organic dye solution, the spin coating being provided at different positions from the center of the substrate. A method for manufacturing an optical disk, characterized in that organic dye solutions having different viscosities are dropped from two or more arranged nozzles, and each nozzle is reciprocally moved in the radial direction of the substrate. 18. The method of manufacturing an optical disc according to claim 17, wherein the organic dye solutions having different viscosities are solvents or organic dye solutions having different solvent compositions. 19. The method of manufacturing an optical disk according to claim 8, further comprising forming a reflective layer by sputtering, the method comprising: forming a shielding plate covering a part of the substrate between the target and the substrate. A method for manufacturing an optical disc, wherein the method is performed by arranging the substrates and rotating the substrate. 20. A method of manufacturing an optical disk according to claim 11, comprising forming the reflective layer by sputtering, the sputtering being carried out using a target whose composition is not constant in the radial direction. Optical disk manufacturing method. 21. An optical disc having a recording layer made of an organic dye, wherein the recording layer has two or more nozzles arranged at different distances from the center of the substrate, and organic dye solutions having different viscosities are dripped. Then, an optical disc having a layer formed by spin coating.