JPH10154351A - Optical recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical recording medium ensuring high recording density and rigidity by laminating an information recording layer having a fine rugged structure on a substrate having a specified modulus of bending elasticity and forming a light transmitting layer having a specified thickness on the recording layer. SOLUTION: An information recording layer 15 having a fine rugged structure is laminate on a substrate 20 having >=7×10<9> Pa (7GPa) modulus of bending elasticity and a light transmitting layer 100 reading information and having sufficiently high transmissivity to laser beam for recording and <=0.3mm uniform thickness is formed on the recording layer 15 by applying a liq. photosetting resin on the layer 15, spinning the substrate 10 at a high rate and setting the spread resin by irradiation with UV.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium and a method for manufacturing the same.

[0002]

2. Description of the Related Art As an optical recording medium for recording various information for audio, video, and the like, a ROM (Read) such as an optical disk, an optical card, a magneto-optical disk, and a phase change optical recording medium for recording or reproducing by light irradiation.
There are optical recording media such as an only memory (rewritable) type, a write-once type, and a rewritable type. For example, in a ROM type such as a compact disk, phase pits, pregrooves, etc., in which data information, tracking servo signals, and the like are recorded on an information recording layer thereof. Also, in the magneto-optical medium of a write-once type, a rewritable type or the like, or a magneto-optical medium by phase change or the like, the fine irregularities such as a pre-group are formed.

FIG. 21 is a schematic sectional view of a conventional optical disk such as a CD.

In this optical recording medium, fine irregularities 2 are formed simultaneously with the injection molding of a transparent substrate 1 having a thickness of 1.2 mm such as polycarbonate, and a reflective film 4 such as an Al vapor-deposited film is formed on the fine irregularities 2. The information recording layer 5
And Further, a protective film 6 made of, for example, an ultraviolet curable resin is laminated on the information recording layer 5 by several μm.

The reading of information from the information recording layer 5 with respect to this optical recording medium is performed by, for example, irradiating the reading light L from one substrate in FIG.

[0006]

However, with the increase in the amount of recorded information, it is necessary to increase the recording density, thereby increasing the numerical aperture of the objective lens of the optical pickup. A needs to be as large as possible. Thus, the numerical aperture of the objective lens, N.P. When A is increased, the distance between the objective lens and the information recording layer 5 needs to be selected to be small. In this case, since the inclination tolerance of the optical recording medium is reduced, the information recording layer 5 and the light incident The distance from the surface, that is, the thickness of the light transmitting layer needs to be sufficiently small, for example, 0.3 mm or less.

In the above-mentioned conventional optical recording medium,
Light is emitted from the transparent substrate 1 side. That is, in the conventional structure, the substrate 1 becomes a light transmitting layer. Therefore, it is only necessary to make the substrate 1 thin, but there is a limit in making this substrate thin.

That is, the substrate 1 is made of a light transmissive resin such as polycarbonate, which is warped immediately after the substrate is produced due to the curing shrinkage of the ultraviolet curable resin used for forming the information recording layer. Is likely to remain,
In addition, in the course of aging, deformation such as warpage due to the adsorption and desorption of moisture in the air of the substrate occurs. When the substrate 1 is manufactured to be thin, the rigidity of the substrate 1 is insufficient. Is more likely to occur.

The deformation that occurs on the substrate 1 due to the above-described causes causes an error in recording and reproduction on the optical recording medium.

In addition, the rotational speed (rpm) of the optical disk when recording and reproducing the optical disk by the player tends to increase in the future, and if the rigidity of the optical recording medium is low, the runout of the disk during high-speed rotation is a serious problem. Become.

Accordingly, the present invention provides a light-transmitting layer having a thin and uniform thickness on the information recording layer and a rigidity of the substrate in order to increase the recording density in accordance with the increase in the amount of recorded information. To secure.

[0012]

The optical recording medium according to the present invention comprises a support substrate having a flexural modulus of 7 × 10 ⁹ (Pa) or more and an information recording layer having a fine uneven structure laminated on the information recording layer. A structure in which light transmitting layers having a uniform thickness of 0.3 mm or less are laminated.

In the optical recording medium according to the present invention, an information recording layer having a fine uneven structure is formed on a supporting substrate having a flexural modulus of 7 × 10 ⁹ (Pa) or more, or the information recording layer is formed on the supporting substrate itself. Is formed on the information recording layer to a thickness of 0.3 mm.
It is manufactured by laminating a light transmitting layer having the following uniform thickness.

According to the present invention, since the rigidity of the optical recording medium can be maintained high, the light transmission on both sides for reading the recorded information or recording the information can be performed in accordance with the future increase in the recording density. The thickness of the layer can be further reduced, whereby the substrate can be effectively prevented from warping or deforming after the substrate is manufactured.

In recording and / or reproduction of recording information, surface deflection when the optical recording medium is rotated at a high speed can be suppressed, and stable recording and reproduction of an optical recording medium with a high recording density can be achieved. be able to.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described.

In the following, a case where the present invention is applied to a disk-shaped optical disk, that is, a disk-shaped optical disk, will be described. However, the present invention is not limited to such an optical disk and a shape. In addition, the present invention can be applied to various optical recording media having fine irregularities such as a card shape and a sheet shape in the information recording layer.

An embodiment of the method of the present invention will be described.

This example has a flexural modulus of elasticity of 7 × 10 ⁹ (7 G (giga)) (Pa) as shown in FIG.
The support substrate 20 described above and the information recording layer 15 having a fine uneven structure are laminated, and information having a thickness of 0.3 mm or less that has a sufficient transmittance to a laser beam for reading and recording information on the information recording layer is provided. This is a case where an optical recording medium having a structure in which light transmitting layers 100 having a uniform thickness are stacked is obtained.

The substrate 10 for an optical recording medium shown in FIG.
On one main surface, fine irregularities 12 such as data recording pits and pre-groups are formed.

As shown in FIG. 2, the substrate 10 is formed by punching a sheet 90 having a uniform thickness, for example, 0.1 mm in thickness and made of a light-transmitting resin such as polycarbonate, for example. In the above, the fine irregularities 12 are formed on the sheet 90 by pressing with the stamper 18.

In this case, as shown in FIG. 2, the belt-shaped sheet 90 that has been guided and transferred between the guide rollers 91 is transferred between the guide rollers 91, and the stamper 18 heated from above the sheet 90 during the transfer. Is pressed to transfer and form fine irregularities 12 such as data recording pits and grooves.

Thereafter, a substrate 10 having fine irregularities 12 formed on one principal surface is manufactured by, for example, punching into a disk shape by a sheet punching machine 93.

Then, as shown in FIG.
An information recording layer 15 is formed thereon by forming a reflective film such as Al or a material film 14 such as a phase change material or a magneto-optical material.

As shown in FIG. 4, the substrate 10 on which the information recording layer 15 is formed is made of a metal such as Al or Ni, a glass, or a reinforced plastic having a flexural modulus of 7 × 10 ⁹ (Pa). It is bonded to, for example, a disc-shaped support substrate 20 having a thickness of, for example, 1.0 mm and made of the above material.

Thereafter, a liquid photocurable resin (ultraviolet curable resin) is applied on the information recording layer 15 and the liquid photocurable resin is stretched by rotating the substrate 10 at a high speed.

Then, for example, ultraviolet irradiation is performed to cure the liquid photo-curable resin to form a light transmitting layer 100 having a thickness of 0.3 mm or less, thereby obtaining a desired optical recording medium.

Further, as shown in FIG. 5, the substrate 10 formed by the sheet 90 made of the light-transmitting resin as described above is placed such that the information recording layer 15 is opposed to the supporting substrate 20.
That is, a configuration in which the information recording layer 15 is placed inside and the liquid photocurable resin 3 is interposed therebetween may be adopted.

Hereinafter, another embodiment will be described.

The optical recording medium of the present invention is not limited to the case where the substrate 10 is formed by pressing a transparent sheet, but the substrate 10 can be formed by injection molding using an injection molding apparatus 60 shown in FIG. .

In this case, fine irregularities 12 are formed on one main surface of the substrate 10 simultaneously with the molding of the substrate 10 by injection molding of a light-transmitting resin such as polycarbonate. The injection molding apparatus 60 shown in FIG. 6 includes a pair of molds 80 made of, for example, a stainless steel, which constitute a cavity 70 for molding the substrate 10.

A stamper 28 for transferring the fine irregularities 12 constituting the information recording layer 15 is arranged and held on a pair of dies 80 used in molding the substrate 10 by, for example, a vacuum chuck (not shown).

First, a light-transmissive resin, for example, molten polycarbonate is poured into the cavity 70 to dissipate heat, and at the same time, the fine irregularities 12 are transferred and solidified by the stamper 28.

In this way, the substrate 10 having the fine irregularities 12 constituting the information recording layer 15 formed on one main surface as shown in FIG. 7 can be obtained.

Then, in the same manner as described above, a reflective film such as Al or a material film 14 such as a phase change material or a magneto-optical material is formed on the fine irregularities 12 to form an information recording layer 15. I do.

The substrate 10 on which the information recording layer 15 is formed in this way is made of a metal such as Al or Ni, a glass, or a reinforced plastic having a flexural modulus of 7 × 10 ⁹ (P
a) Adhesion is made to, for example, a disc-shaped support substrate 20 having a thickness of, for example, 1.0 mm and made of the above-mentioned materials.

Thereafter, a liquid photocurable resin is applied on the information recording layer 15, and the liquid photocurable resin is stretched by rotating the substrate 10 at a high speed.

The liquid photo-curable resin is cured by irradiating ultraviolet rays to form a light-transmitting layer 100 having a thickness of 0.3 mm or less, so that a desired optical recording medium can be obtained.

In the above-described example, the substrate 10 on which the fine irregularities 12 forming the information recording layer 15 have been transferred and the material having a flexural modulus of elasticity of 7 × 10 ⁹ (Pa) or more, for example, having a thickness of 1 × 10 ⁹ (Pa). 0 mm, for example, a disk-shaped support substrate 20
Although the optical recording medium of the configuration to be bonded has been described,
The present invention is not limited to this example.
It is made of a material of 10 ⁹ (Pa) or more and has a thickness of, for example, 1.
A so-called photopolymerization (Photo Polymerization: 2)
The present invention can be applied to a case where the information recording layer 15 is directly formed by the P) method.

As shown in FIG. 8, a method for manufacturing an optical recording medium by the 2P method is as follows. First, as shown in FIG. 8, a stamper 110 having fine irregularities formed on one main surface and a base plate 111 serving as a base material of the optical recording medium are provided. And prepare. Here, the stamper 110 is made of a metal such as nickel, for example. Also, this stamper 110
Is used in which fine irregularities formed on one main surface are used as a desired signal. On the other hand, the base plate 111
A light-transmitting synthetic resin material having a thickness of about 0.1 mm is used. In the present embodiment, polycarbonate is used as the material of the base plate 111, but the material is not limited to this, and polymethyl methacrylate (PMMA) or the like may be used.

Next, as shown in FIG. 8, a 2P resin 112 is dropped on the stamper 110 described above. At this time, the 2P resin 112 is dropped on the stamper 110 in a circumferential shape. The 2P resin 112 may be applied by dripping onto the stamper 110.
10 and the base plate 111 may be arranged at a predetermined interval, and the space between the stamper 110 and the base plate 111 may be filled with the 2P resin 112. As the 2P resin 112, an ultraviolet curable resin that is cured by irradiation with light having a wavelength in the ultraviolet region is used.

Next, as shown in FIG.
The base plate 1 is placed on the stamper 110 where
11 is placed, and a predetermined pressure is applied by a roller 113 or the like to be pressed. After that, the 2P resin 112 is cured by irradiating the base plate 111 with ultraviolet light by an ultraviolet irradiation device 114. In this manner, the 2P resin layer 11 having a thickness of about 5 to 10 μm is formed by applying pressure by, for example, a roller 113 or the like and applying ultraviolet light to cure the 2P resin 112.
Form 2

Next, as shown in FIG. 10, the 2P resin layer 112 to which the fine irregularities formed on the stamper 110 are transferred by the above-described steps, and the base plate 111
Are removed from the stamper 110. Then, a replica including the base plate 111 and the stamper 110 is completed.

Next, as shown in FIG. 11, the functional layer 1 is placed on the side of the replica where the 2P resin layer 112 is formed.
15 and a protective film 116 is formed on the functional layer 115. In the case where an optical recording medium exclusively for reproducing information signals is formed, the functional layer 115 forms a reflective film. When an optical recording medium capable of recording and reproducing information signals is formed, the functional layer 115 is formed on the 2P resin layer 112 in the order of a dielectric film, a recording film, a dielectric film, and a reflective film. . The recording film may be a magneto-optical material or a phase change material.

Next, as shown in FIG. 11, the replica on which the functional layer 115 and the protective layer 116 are formed by the above-described steps is bonded to the support substrate 117 to obtain an optical recording medium. The support substrate 117 may have a flat surface to which the replica is adhered.

Further, according to the present invention, the support substrate 117 and the substrate on which the information recording layer is formed are not separately formed, and the substrate is previously formed using a material having a flexural modulus of 7 × 10 ⁹ (Pa) or more. This can be applied to the case where the fine irregularities are formed simultaneously with the transfer.

That is, as shown in FIG. 8, the substrate 10 is manufactured by the injection molding apparatus 62.

This is because the substrate 4 is formed by injection molding of a reinforced plastic resin having a flexural modulus of 7 × 10 ⁹ (Pa) or more.
At the same time as the molding of 0, fine irregularities 42 are formed on one main surface of the substrate 40.

The substrate manufacturing apparatus 62 shown in FIG.
A pair of molds 82, which are made of, for example, a stainless steel, constituting the cavity 70 for molding the O are opposed to each other.

On a pair of dies 82 used for molding the substrate 40, a stamper 38 for transferring the fine irregularities 42 constituting the information recording layer 45 is arranged and held by, for example, a vacuum chuck (not shown).

First, the molten reinforced plastic resin is poured into the cavity 70 to radiate heat, and at the same time, the fine irregularities 42 are transferred and solidified by the stamper 38.

In this manner, a substrate 40 having fine irregularities 42 constituting an information recording layer 45 formed on one main surface as shown in FIG. 13 can be obtained.

Then, in the same manner as described above, a reflective film such as Al or a material film 44 such as a phase change material or a magneto-optical material is formed on the fine unevenness 42 to form the information recording layer 45. Form.

Thereafter, a liquid photocurable resin is applied on the information recording layer 45, and the liquid photocurable resin is stretched by rotating the substrate 40 at a high speed.

By irradiating ultraviolet rays to cure the liquid photocurable resin, a light transmitting layer 100 having a thickness of 0.3 mm or less is formed as shown in FIG. 14 to obtain a desired optical recording medium. .

Similarly, another example in which the supporting substrate and the substrate on which the information recording layer is formed is integrally formed without being separately formed is made of a material having a flexural modulus of 7 × 10 ⁹ (Pa) or more. There is a method in which fine asperities for forming an information recording layer are formed on a supporting substrate by etching using a photoresist.

As shown in FIG. 15, for example, a thickness of 1.2 m
m on a glass substrate 30 having a flexural modulus of 7 × 10 ⁹ (Pa) or more, for example, a photoresist 31 sensitive to ultraviolet rays.
Is applied in a uniform thickness.

Thereafter, as shown in FIG. 16, exposure and development are performed by a laser recording and exposure apparatus (not shown) to form a pattern 50 such as predetermined pits and groups on the photoresist 31.

Next, as shown in FIG. 17, using the pattern 50 as a mask, the glass substrate 30 is etched.
The pattern 50 such as pits and groups is transferred.

Thereafter, as shown in FIG. 18, when the photoresist 31 is removed, fine irregularities 52 constituting the information recording layer are formed on the glass substrate 30.

Then, in the same manner as described above, a reflective film such as Al or a material film 54 such as a phase change material or a magneto-optical material is formed on the fine unevenness 52 to form the information recording layer 55. I do.

Thereafter, a liquid photocurable resin is applied on the information recording layer 55, and the liquid photocurable resin is stretched by rotating the substrate 40 at a high speed.

By irradiating ultraviolet rays to cure the liquid photo-curable resin, a light transmitting layer 100 having a thickness of 0.3 mm or less is formed as shown in FIG. 19, and a desired optical recording medium can be obtained. .

The method for forming the light transmitting layer 100 is not limited to the above-described method. For example, a liquid photocurable resin is applied on the information recording layer 15,
This is stretched, and a uniform thickness of, for example, 0.1 m is further embedded thereon so as to bury fine irregularities such as pits and groups.
m, a transparent sheet made of a light-transmissive resin is pressed, light is irradiated from the back side, and the light-curable resin is light-cured, whereby the transparent sheet is bonded to the light-transmissive layer 10.
0 can also be formed.

In this case, the transparent sheet is made of a material that is optically uniform, has sufficiently high transparency, and has extremely low birefringence.

In the above-described example, the so-called single-sided reading type optical recording medium having a single-layer structure has been described.
The present invention is not limited to this example.

For example, as shown in FIG. 20, an optical recording medium having a so-called double-sided reading type two-layer structure in which a substrate 10 on which an information recording layer 15 is formed is laminated on both main surfaces of the support substrate 20 described above. Can be obtained.

That is, in an optical recording medium having a two-layer structure having a structure as shown in FIG. 20, information is read by irradiation of light L from both sides.

In the above-described embodiment, the optical recording medium having the ROM type configuration has been mainly described.
The present invention can be applied to a rewritable type, a write-once type, or a WO (write 0nce) type optical recording medium having a phase change material.

The above-described optical recording medium having a two-layer structure has an information recording layer formed on at least one main surface, but the other main surface is not limited to information recording. A fine uneven surface of a character or a label may be formed.

As described above, in the present invention, a support substrate having a flexural modulus of 7 × 10 ⁹ (Pa) or more and an information recording layer having an information recording surface having a fine uneven structure are laminated. Further, a light-transmitting layer having a uniform thickness of 0.3 mm or less and having a sufficient transmittance to a laser beam for reading information is laminated.

As a result, the rigidity of the optical recording medium can be kept high, so that the light-transmitting layer 100 on the side of reading the recorded information or recording the information can be used in accordance with the future increase in recording density. Could be further reduced in thickness.

Thus, after the substrate is manufactured, the warpage of the substrate,
Deformation can be effectively avoided. Further, during the reproduction of the recorded information, the surface runout when the optical recording medium was rotated at a high speed could be suppressed, and the stable recording and reproduction of the optical recording medium with a high recording density could be achieved.

[0074]

According to the present invention, the rigidity of the optical recording medium can be kept high, so that the recording information can be read or the information recorded on the surface side can be recorded in accordance with the future increase in recording density. Since the thickness of the light transmission layer 100 could be further reduced, the tilt margin of the optical recording medium could be secured.

Thus, after the substrate is manufactured, the warpage of the substrate,
Deformation can be effectively avoided. Further, during the reproduction of the recorded information, the surface runout when the optical recording medium was rotated at a high speed could be suppressed, and the stable recording and reproduction of the optical recording medium with a high recording density could be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical recording medium of the present invention.

FIG. 2 is a schematic view showing an example of an optical recording medium substrate manufacturing apparatus according to the present invention.

FIG. 3 is a schematic sectional view showing a state where an information recording layer is formed on a substrate.

FIG. 4 is a schematic sectional view showing a state in which a substrate and a support substrate are stacked.

FIG. 5 shows a schematic cross-sectional view of an example of the optical recording medium of the present invention.

FIG. 6 is a schematic view showing an example of an optical recording medium substrate manufacturing apparatus of the present invention.

FIG. 7 is a schematic sectional view of a substrate of the optical recording medium of the present invention.

FIG. 8 is a diagram illustrating an example of a base plate and a stamper in which 2P resin is dropped.

FIG. 9 is a diagram showing an example of a state in which a base plate and a stamper are opposed to each other via a 2P resin, pressed with a roller, and irradiated with ultraviolet rays by an ultraviolet irradiation device.

FIG. 10 is a view showing an example of a state in which a base plate and a cured 2P resin on which fine irregularities have been transferred are peeled from a stamper.

FIG. 11 is a view showing a replica in which a functional film and a protective film are formed on a 2P resin layer, and a support substrate.

FIG. 12 is a view showing a manufacturing process of the substrate of the optical recording medium of the present invention.

FIG. 13 is a schematic sectional view of a substrate of the optical recording medium of the present invention.

FIG. 14 is a schematic sectional view of an example of the optical recording medium of the present invention.

FIG. 15 is a schematic sectional view showing a state where a photoresist is applied on a glass substrate.

FIG. 16 shows a process chart of exposing a photoresist.

FIG. 17 is a schematic sectional view showing a state where a predetermined pattern of a photoresist is formed on a glass substrate.

FIG. 18 shows a state diagram in which fine irregularities are formed by etching a glass substrate.

FIG. 19 is a schematic sectional view of an example of the optical recording medium of the present invention.

FIG. 20 is a schematic sectional view of an example of an optical recording substrate having a two-layer structure according to the present invention.

FIG. 21 shows a schematic sectional view of a conventional optical recording medium.

[Explanation of symbols]

1, 10, 40 substrate, 2, 12, 42, 52 fine irregularities, 3 liquid photocurable resin, 4 reflective film, 5, 15, 4
5, 55 information recording layer, 6 protective film, 14, 44, 54
Material film, 18, 28, 38 stamper, 20 support substrate, 30 glass substrate, 31 photoresist, 50
Pattern, 60, 62 injection molding device, 70 cavity, 80, 82 mold, 90 sheet, 91 guide roller, 93 sheet punching machine, 100 light transmitting layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiyuki Kashiwagi 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Noriyuki Arakawa 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (11)

[Claims] 1. A support substrate having a flexural modulus of 7 × 10 ⁹ (Pa) or more and an information recording layer having a fine uneven structure are laminated, and the information recording layer has a uniform thickness of 0.3 mm or less. An optical recording medium characterized in that the optical recording medium has a structure in which the light transmitting layers are laminated. 2. The optical recording medium according to claim 1, wherein the information recording layer having the fine uneven structure is formed on one main surface of a sheet-like thin film. 3. The optical recording medium according to claim 1, wherein an information recording layer having a fine uneven structure is formed on one main surface of the support substrate. 4. The optical recording medium according to claim 1, further comprising a light transmitting layer having a thickness of 0.3 mm or less on the information recording layer. 5. An information recording layer having a fine concavo-convex structure on a supporting substrate having a flexural modulus of 7 × 10 ⁹ (Pa) or more, or an information recording layer formed on the supporting substrate itself. A method for manufacturing an optical recording medium, comprising: laminating a light transmitting layer having a uniform thickness of 0.3 mm or less on a layer. 6. The method for manufacturing an optical recording medium according to claim 5, wherein the information recording layer is formed by a photopolymerization method. 7. The method according to claim 5, wherein a sheet-like thin film on which an information recording layer having a fine uneven structure is formed is laminated on the support substrate. 8. The method for manufacturing an optical recording medium according to claim 5, wherein a substrate having an information recording layer in which a fine uneven structure is formed by injection molding is laminated on the support substrate. 9. A glass substrate is used as the support substrate, a photoresist is laminated on the glass substrate, a predetermined pattern is formed by exposing the photoresist, and the glass substrate is etched using the pattern as a mask. 6. An information recording surface having a fine uneven structure to be formed is formed.
3. The method for producing an optical recording medium according to item 1. 10. A light-transmitting layer having a thickness of 0.3 mm or less is formed by applying and stretching a liquid photocurable resin on the information recording layer and exposing and curing the liquid photocurable resin. The method for manufacturing an optical recording medium according to claim 5, wherein: 11. The optical recording according to claim 5, wherein a sheet made of a transparent photo-curable resin is adhered on the information recording layer to form a light transmitting layer having a thickness of 0.3 mm or less. The method of manufacturing the medium.