JP2002367231A - Optical recording medium and method of manufacturing for the same as well as metal mold for molding substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve signal characteristics and to assure high reliability by preventing the occurrence of warpage and improving the uniformity of an adhesive layer of an optical recording medium constructed by bonding two sheets of substrates to each other. SOLUTION: The outer peripheral part of a bonding surface 1a of the disk substrate 1 is provided with a recessed part 1d held recessed from the bonding surface 1a. The recessed part 1d is formed by a metal mold having a projecting part in the position corresponding to the recessed part 1d in a step of manufacturing the disk substrate 1 by an injection molding method. The recessed part 1d at the bonding surface 1a of the disk substrate 1 is disposed like a belt to a circumferential shape in the outer peripheral part of the disk substrate 1. Flashes 1e are produced to the circumferential shape on the outer peripheral side of the recessed part 1d. The width Δr of the outer peripheral belt-like segment is regulated to 0.1 to 1.5 mm of width which is the skirt of the flashes 1e.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, a method of manufacturing the same, and a mold for molding a substrate, and more particularly to a method suitable for application to an optical disk manufactured by laminating two disks. is there.

[0002]

2. Description of the Related Art Hitherto, optical recording media and magnetic recording media for recording various kinds of information such as audio applications, video applications, and personal computer applications are known. In these optical recording media and magnetic recording media, information signals are written in embossed pits and grooves. In these optical recording media and magnetic recording media, a recording film is provided on the surface of a plastic substrate. There are a magneto-optical disk using an optical effect and a magnetic disk on which a signal is written by magnetism.

[0003] As a method for forming an information signal portion having fine irregularities such as phase pits and pregrooves in which data information and tracking servo signals are recorded in the information signal portion, an injection molding method using a stamper is known. Generally done.

By the way, in these recording media,
In recent years, the development of a large recording capacity has been actively pursued. In the process of increasing the storage capacity, a digital versatile disc (DVD) whose outer diameter is the same as that of a compact disc (CD) and whose storage capacity has been drastically increased has been developed. Developed and put into practical use. In this DVD, it is possible to store data for one movie while maintaining the image quality of a current television broadcast.

Further, in this DVD, in order to increase the recording density and realize a large recording capacity, a laser beam having a shorter wavelength than a laser beam used for reproducing a CD or the like is used, and an information signal is reproduced. Recording / reproduction is performed. And
In this DVD, in order to further increase the recording capacity, a single-disc disk having a thickness of about ＣＤ of the thickness of a CD is placed on the side where the information signal portion is provided inside each other. It is configured by sticking together. By reducing the thickness of the substrate in this way, the distance from the surface on which the laser beam is incident, that is, the so-called DVD surface, to the information signal portion is reduced. A description will be given below of a manufacturing process of a bonded type disk formed by bonding two single-plate disks such as a DVD.

That is, in the case of manufacturing a bonded disk, first, a resin material such as polycarbonate is formed into a disk by injection molding to manufacture a disk substrate. At this time, the disk substrate is manufactured such that its outer diameter is larger than the outer diameter of the bonded disk as the final product. Specifically, when the outer diameter of the bonded disc as the final product is 130 mm, the outer diameter of the disc substrate manufactured by the injection molding method is 133.4 mm.

Next, two disk substrates manufactured by the injection molding method are prepared. Then, a laminated film having a recording layer and the like is formed on each of the main surfaces of these two disk substrates by a sputtering method. Thus, an information signal portion is formed on each of the main surfaces of the two disk substrates.

Next, after a radical-type ultraviolet-curable resin is applied to the main surface of the disk substrate on which the information signal portion is formed, the ultraviolet-curable resin is cured by irradiating it with ultraviolet rays. As a result, a protective layer made of an ultraviolet curable resin is formed on the information signal portion on one main surface of the disk substrate.

Next, a hot-melt type adhesive is applied by a roll coating method on the main surface of the disk substrate on which the protective layer is formed. Thereafter, the two disk substrates to which the adhesive has been applied are bonded together by abutting and pressing the main surfaces to which the adhesive has been applied. As a result, the two disk substrates are bonded via the adhesive.

[0010] Thereafter, the two bonded disk substrates are mounted on a cutting device. Here, the cutting device is a device configured to be able to cut and remove an outer peripheral portion of the cutting target by pressing a cutting blade while rotating the mounted cutting target. Then, the two disc substrates bonded to each other are mounted on the cutting device, and the outer peripheral portions are cut and removed. Thereby, the outer diameter dimension is set to a predetermined value. Here, the outer diameter of the two disk substrates bonded to each other is 133.4 mm. And
The outer diameters of these two disk substrates are set to 130 mm by cutting and removing the outer peripheral portions with a cutting device.

As described above, a bonded disc is manufactured.

In the field of optical recording, the density of information signals has been rapidly increased in recent years. The increase in the density of an optical disk is mainly achieved by shortening the wavelength of a laser and increasing the numerical aperture (NA) of a condenser lens.

For example, in a currently widespread CD, the wavelength of a laser beam used for reproduction is 780 nm,
An optical system with an NA of 0.45 is used. Also CD
In a DVD having a storage capacity several times as large as that described above, an optical system having a wavelength of 630 nm and an NA of 0.6 for laser light used for recording / reproducing is used. With the increase in NA, the transmission substrate that transmits laser light is also gradually becoming thinner in order to reduce the influence of aberration. Specifically, in the case of a CD, the thickness of the disc substrate is 1.2 mm.
In the case of DVD, the thickness of the disc substrate is set to 0.6.
mm, which contributes to measures against disk warpage.

In recent years, in order to further increase the density, an optical system has been proposed in which the wavelength of laser light during recording / reproduction is 400 nm and the NA is 0.85. When this high NA lens is used, 0.6 mm
It is necessary to reduce the thickness of the substrate to about 0.1 mm. However, it is very difficult to produce an ultra-thin substrate having a thickness of 0.1 mm using a commonly used injection molding apparatus.

Therefore, on the main surface of the substrate on which the fine irregularities are transferred, the stacking order of the stacked films in the conventional disk is reversed.
After performing a so-called reverse-order film formation in which a reflective film, a first dielectric film, a recording film, and a second dielectric film are sequentially laminated, a light-transmitting layer having a thickness of 0.1 mm covers the laminated film. Have been proposed. This makes it possible to manufacture a disk for use in an optical system in which the wavelength of laser light during recording / reproduction is 400 nm and the NA is 0.85 without manufacturing an ultra-thin substrate.

On the other hand, there has been proposed an optical recording medium having a structure in which two disk-shaped recording media as described above are prepared and bonded via an adhesive layer. This optical recording medium is shown in FIG.

As shown in FIG. 7, in this optical recording medium, a first recording layer 102 having a laminated structure and a first light transmitting layer 103 are provided on one main surface of a first disk substrate 101. And two disks having a laminated structure of a second recording layer 105 and a second light transmitting layer 106 provided on one main surface of a second disk substrate 104, with an adhesive layer 107 interposed therebetween. It has a structure.

Of these, the first disk substrate 10
The first and second disk substrates 104 are manufactured by an injection molding process of injecting polycarbonate (PC) into an injection mold.

FIG. 8 shows a closed state of the injection molding apparatus used in the injection molding method. That is, as shown in FIG. 8, in the injection molding apparatus for molding the disk substrate, a fixed mold 202 fixed to the fixed mold 201 and a movable mold 204 incorporated in the movable mold 203 are mutually separated. It is configured to have a mold 205 arranged opposite to each other. The fixed mold 202 and the movable mold 2
When the pieces 04 abut against each other, a molding cavity 206 is formed between the fixed mold 202 and the movable mold 204. The molding cavity 206 has a shape corresponding to the disk substrate to be molded. A cooling pipe 202 a is provided inside the fixed mold 202, and a cooling pipe 204 a is also provided inside the movable mold 204.

Further, the fixed mold 20 in the injection molding apparatus is used.
2, an insertion hole 202b is formed at the center position.
A fixed bush 207 having a substantially annular cylindrical shape is inserted through the insertion hole 202b. A sprue bush 208 is provided so as to fit into the fixed bush 207.

The sprue bush 208 has an annular shape, and an injection hole 209 is provided along a central axis of the annular shape. This injection hole 209
Is configured so that a synthetic resin material such as a molten polycarbonate resin supplied from an injection device (not shown) can flow into the molding cavity 206. That is, the tip side of the sprue bush 208 is configured to face the inside of the molding cavity 206.

The surface of the mold constituting the molding cavity 206 of the fixed mold 202, that is, the movable mold 204
A stamper 210 is mounted on the surface facing the side. The stamper 210 is formed in a disk shape having a center hole 210a at the center. This stamper 210
Is for forming a concavo-convex pattern corresponding to an information signal or a pre-groove forming a recording track on a disk substrate. The inner peripheral portion of the stamper 210 is configured to be supported by a cylindrical stamper inner peripheral holder (not shown) at the peripheral edge of the center hole 210a. On the other hand, the outer peripheral portion of the stamper 210 is configured to be supported by an outer peripheral ring 211 on a disk-shaped outer peripheral edge. The stamper 210 is attached to the fixed mold 202 by the stamper inner peripheral holder and the outer ring 211. Specifically, in the outer peripheral ring 211, the outer peripheral portion of the stamper 210 is pushed toward the molding cavity 206 of the fixed mold 202 by the land portion 211 b provided in a convex shape on the innermost peripheral upper edge of the inner peripheral ring portion 211 a. In a state where the outer peripheral ring portion 211c is held in contact with the fixing mold
02. A stamper inner peripheral holder (not shown) that supports the peripheral edge of the center hole 210a of the stamper 210 is fitted on the outer peripheral side of the fixed bush 207, and the molding cavity 20 of the sprue bush 208 is formed.
6 and is attached to the fixed mold 202.

On the other hand, an insertion hole 204b is formed at the center of the movable mold 204. In the insertion hole 204b of the movable mold 204, a cylindrical eject sleeve 213 is inserted and provided. The eject sleeve 213 is configured to be able to advance and retreat with respect to the molding cavity 206, and is supported by a movable mold. The eject sleeve 213 has its front end face facing the molding cavity 206 slightly inserted into the movable mold 204. A cylindrical gate cut piston 214 is fitted and provided inside the cylinder of the eject sleeve 213. This gate cut piston 214
Has a front end face facing the molding cavity 206 slightly projecting from a front end face of the eject sleeve 213.

As described above, the injection molding apparatus is configured. In this injection molding apparatus, the fixed mold 202, the movable mold 204, and the outer ring 211
Thus, the molding cavity 206 is formed. That is, the outer peripheral portion of each of the first disk substrate 101 and the second disk substrate 104 to be molded is defined by the outer peripheral ring 211 of the outer peripheral portion of the molding cavity 206. Here, an enlarged view of the periphery of the outer peripheral ring 211 is shown in FIG.

As shown in FIG. 9, the inner peripheral ring portion 211a is provided around the outer peripheral ring 211 in the mold clamping state.
Clearance C ₁ between the land portion 211b and the stamper 210 is present about ten [mu] m, the inner peripheral ring portion 211a
The clearance C ₂ between the movable mold 204 and the
Degree exists.

When the first disk substrate 101 and the second disk substrate 104 are molded by using this injection molding apparatus, first, the molten resin is molded from an injection nozzle (not shown) through an injection hole 209. Cavity 2
Inject into 06 and fill. The filled molten resin is
The gap between the outer peripheral ring 211 and the stamper 210, i.e. with entering the portion of the clearance C _1, penetrates the gap, i.e. the portion of the clearance C ₂ between the outer ring 211 and the movable mold 204. As a result, burrs 215 and 216 are generated respectively. That is, in the first disk substrate 101 and the second disk substrate 104 molded by using the above-described injection molding apparatus, burrs 215 and 216 are generated on the respective outer peripheral portions.

[0027]

The first disk substrate 101 and the second disk substrate 104 are referred to as one principal surface on which the first recording layer 102 and the second recording layer 105 are provided. When a bonding type optical recording medium is manufactured by bonding the other main surfaces (bonding surfaces) on the opposite sides via the bonding layer 107, as shown in FIG. At the respective outer peripheral portions of the second disk substrate 104, the tips of the burrs 216 come into contact with each other. As a result of interference at these outer peripheral portions, the first disk substrate 101 and the second
Of the disk substrate 104 of the adhesive layer 1
The film thickness of 07 cannot be kept uniform over the entire surface of the disk-shaped optical recording medium.

That is, the disk substrate 10 shown in FIG.
In each of the outer peripheral portions 1 and 104, the thickness of the first disk substrate 101 and the second disk substrate 104 at an arbitrary position P ₁ is d _1, and similarly, an arbitrary position P ₂
If the thickness at d is d ₂ , d ₁ ≠ d ₂ . Specifically, the thickness of the adhesive layer 107 is 4 in the vicinity of a radius of 65 mm near the outer periphery where the burr 216 exists.
A variation of about 5 to 100 μm occurs.

Further, such a first disk substrate 1
01 and the second disk substrate 104, the burr 2
If the optical recording medium of the above-described bonded type is manufactured by bonding together with the adhesive layer 107 interposed therebetween in a state where 16 is generated, skew occurs in this optical recording medium.

Due to the occurrence of such a skew, it has been difficult to improve the optical characteristics of a laminated optical recording medium. Therefore, it has been desired to develop a technology capable of suppressing the occurrence of such skew, improving the recording / reproducing characteristics, and improving the optical characteristics.

Therefore, an object of the present invention is to prevent the occurrence of warpage and reduce the nonuniformity of the thickness of the adhesive layer used for bonding in an optical recording medium manufactured by bonding two substrates. An object of the present invention is to provide an optical recording medium capable of improving the uniformity, thereby improving the signal characteristics of the optical recording medium, and ensuring high reliability, and a method of manufacturing the same.

Another object of the present invention is to prevent the occurrence of warpage in two bonded substrates when the two substrates are bonded to each other, and to be used for bonding. An object of the present invention is to provide a substrate molding die capable of molding a substrate, capable of ensuring uniformity of an adhesive layer.

[0033]

In order to achieve the above object, a first aspect of the present invention is directed to a first aspect of the present invention, wherein an information signal section configured to record / reproduce an information signal is provided on one main surface. In an optical recording medium having a structure in which another main surface of the first substrate opposite to the side on which the information signal portion is provided and a second substrate are bonded, an outer peripheral portion of the other main surface of the first substrate A portion thinner than the other portion of the first substrate is provided, and a portion thinner than the other portion of the second substrate is provided on an outer peripheral portion of a surface of the second substrate to be bonded to the first substrate. It is characterized by having.

In the first invention, typically, an information signal section is provided on one main surface of the second substrate opposite to the surface to be bonded to the first substrate.

In the first invention, typically, the portion thinner than the other portion of the first substrate is configured to be thinner by 10 μm to 200 μm than the other portion, and The portion thinner than the other portion is configured to be thinner by 10 μm or more and 200 μm or less than the other portion. Further, in the first invention, preferably, the portion thinner than the other portion of the first substrate is 20 times smaller than the other portion.
μm or more and 200 μm or less,
The portion thinner than the other portion of the second substrate is configured to be 20 μm or more and 200 μm or less thinner than the other portion.

In the first invention, typically, the outer peripheral portion is in a range from 0.1 mm to 1.5 mm inward from the outer peripheral edge of the first substrate and / or the second substrate. It is.

In the first invention, typically, the first substrate and the second substrate have a planar annular shape. Preferably, a portion thinner than the other portion of the first substrate and the second substrate is provided in a strip shape, and more preferably, a portion thinner than the other portion of the first substrate and the second substrate. Are provided on the entire circumference of the planar annular outer peripheral portion.

According to a second aspect of the present invention, there is provided a method of manufacturing an optical recording medium, comprising the steps of manufacturing two substrates and bonding the respective bonded surfaces of the two substrates to each other via an adhesive layer. Wherein a portion thinner than other portions of the substrate is formed on an outer peripheral portion of a bonding surface of the substrate.

In the second invention, typically, a step of forming an information signal portion configured to be capable of recording and / or reproducing information signals on a main surface of the substrate opposite to the bonding surface. Having.

In the second invention, typically, 2
A step of forming an information signal portion configured to be capable of recording and / or reproducing information signals on a main surface of one of the substrates opposite to the bonding surface.

In the second aspect of the invention, typically, a portion thinner than the other portion of the substrate is 10 times smaller than the other portion.
μm or more and 200 μm or less, preferably 20 μm
It is formed to be thin not less than m and not more than 200 μm.

In the second invention, typically, the outer peripheral portion is 0.1 mm from the outer peripheral end of the substrate toward the inner peripheral side.
It is in the range of not less than 1.5 mm.

In the second invention, typically, the substrate has a planar annular shape, and preferably, a portion thinner than other portions of the substrate is formed in a band shape. More preferably, a portion of the substrate that is thinner than the other portions is formed on the entire circumference of the planar annular outer peripheral portion.

According to a third aspect of the present invention, a mold is provided which has a mold capable of forming a cavity and which can be opened and closed with each other, and in which a resin is injected into the cavity of the mold to form a substrate. In the substrate molding die, a convex portion is provided on an outer peripheral portion of a surface constituting the cavity of one of the molds constituting the cavity.

In the third aspect of the invention, typically, the protruding portion rises by 10 μm or more and 200 μm or less as compared with the other portion of one of the molds constituting the cavity. Preferably, 20 μm or more and 200 μm
I'm excited below.

In the third invention, typically, the outer peripheral portion is within a range of 0.1 mm or more and 1.5 mm or less from the outer peripheral end of the formed cavity toward the inner peripheral side.

In the third aspect, typically, the cavity has a disk shape, and preferably, the convex portion has
It is provided in a band shape on the surface constituting the cavity of one mold. In the third aspect of the invention, more preferably, the convex portion is provided on the entire outer peripheral portion of the surface constituting the cavity of the one mold.

In the present invention, the first substrate and the second substrate
The substrate material is typically polycarbonate (P
C) A resin, but other thermoplastic resins can also be used, and a low water-absorbing resin such as a cycloolefin polymer (specifically, ZEONEX (registered trademark)) can also be used.

According to the present invention, preferably, a UDO (Ultra-Ultra) is formed by bonding two substrates having a thin light transmitting layer.
Density Optical) and an optical recording medium such as a substrate molding die used for manufacturing a disk substrate used for the optical recording medium.
Applied to an optical recording medium configured to record and reproduce information signals using a semiconductor laser of about 50 nm or about 405 nm, and a substrate molding die used for manufacturing a substrate used for the optical recording medium. It is possible to Further, the present invention can be applied to optical recording media other than the disc-shaped optical recording medium. Specifically, the present invention is applicable to various optical recording media having fine irregularities such as a card or a sheet as an information recording section. It is possible to apply.

According to the optical recording medium and the method of manufacturing the same according to the present invention, and the disk substrate forming mold, two substrates are formed and these two substrates are bonded to each other. In this case, it is possible to prevent the protrusions of the outer peripheral portions of the two substrates from protruding more than the respective bonding surfaces of the two substrates, so that the protrusions of the outer peripheral portions contact each other. Can be prevented.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

First, a laminated optical recording medium according to an embodiment of the present invention will be described. FIG. 1 shows a laminated optical recording medium according to this embodiment.

As shown in FIG. 1, in the optical recording medium according to this embodiment, the bonding surface 1a of the first disk substrate 1 and the bonding surface 2a of the second disk substrate 2 And are bonded together. In addition, a center hole 1b is provided at the center of the first disk substrate 1, and a center hole 2b having substantially the same diameter as the center hole 1b is provided at the center of the second disk substrate 2.

The information signal portion 4 and the information signal portion 4 are provided on the main surface 1c of the first disk substrate 1 opposite to the bonding surface 1a.
In a region covering the information signal section 4, a light transmitting layer 5 in which an adhesive layer and a light transmitting sheet are sequentially laminated is sequentially provided. Similarly, the bonding surface 2a of the second disk substrate 2
On the opposite main surface 2c, an information signal portion 6 and, in a region covering the information signal portion 6, a light transmitting layer 7 in which an adhesive layer and a light transmitting sheet are sequentially laminated are sequentially provided. The thickness of the light transmitting layers 5 and 7 is, for example, about 100 μm, and in this embodiment, the wavelength of the laser light is 4 μm.
The optimum film thickness is selected by setting the optical system NA to about 0.55 nm and the optical system NA to about 0.85.

In the outer peripheral portion of the bonding surface 1a of the first disk substrate 1, there is provided a concave portion 1d in a so-called concave state which is thinner than the other substrate portion of the bonding surface 1a. The concave portion 1d is generated at the stage of molding the first disk substrate 1 by an injection molding method using an injection molding device described later. A burr 1e is formed on the outer peripheral side of the recess 1d. The burrs 1e are generated at the stage of forming the first disk substrate 1 by an injection molding method using an injection molding apparatus described later. The height of the burr 1e is 10 to 200 μm from the bottom of the recess 1d.
About 20 to 200 μm in most cases.

FIG. 2 shows the first disk substrate 1 before bonding, and FIG. 3 shows an enlarged view of the burr 1e of the first disk substrate 1. As shown in FIG. As shown in FIG. 2, when the bonding surface 1a of the first disk substrate 1 and the bonding surface 2a of the second disk substrate 2 are bonded via the bonding layer 3, the first disk Burrs 1e and 2e on the outer peripheral portions of the substrate 1 and the second disk substrate 2, respectively.
However, in order to prevent contact and interference with each other, the height of the burr 1 e from the bonding surface 1 a is 1 /
It is set to be 2 or less. Preferably, as shown in FIG. 3, in order to prevent the burr 1e from protruding from the bonding surface 1a, the depth h of the concave portion 1d from the bonding surface 1a is set to about the height of the burr 1e, Specifically, 1
Range of 0 to 200 μm (10 μm ≦ h ≦ 200 μm)
, Preferably in the range of 20 to 200 μm (20 μm ≦ h
≦ 200 μm). Similarly, a concave portion 2d recessed from the bonding surface 2a is provided on the outer peripheral portion of the bonding surface 2a of the second disk substrate 2. The recess 2d is generated at the stage of molding the first disk substrate 1 by an injection molding method using an injection molding device described later. A burr 2e is formed on the outer peripheral side of the recess 2d. The burrs 2e are generated at the stage of forming the second disk substrate 2 by an injection molding method using an injection molding device described later. Also, the height of the burr 2e from the bonding surface 2a is 10 mm from the bottom of the recess 2d.
〜200 μm, most often 20-200 μm. Further, for the same reason as in the first disk substrate 1 described above, the height of the burr 2e from the bonding surface 2a is set to be equal to or less than 1/2 of the bonding layer 3. Preferably, in order to prevent the projection from the bonding surface 2a, the depth h of the recess 2d from the bonding surface 2a is set to about the height of the burr 2e.
Within the range of ~ 200 μm (10 μm ≦ h ≦ 200 μm)
Preferably, it is in the range of 20 to 200 μm (20 μm ≦ h ≦ 2
00 μm).

The first disk substrate 1 shown in FIG.
As shown in FIG. 2B in a plan view corresponding to FIG. 2A, the concave portion 1d in the bonding surface 1a is provided on the outer peripheral portion of the first disk substrate 1 in a circumferential shape. The burrs 1e are formed circumferentially on the outer peripheral side of the concave portion 1d.
At this time, as shown in FIG. 2A and FIG.
The width Δr of a so-called outer peripheral band portion formed between the deepest portion from the bonding surface 1a of d and the outer periphery of the first disk substrate 1 is selected to be approximately the width serving as the foot of the burr 1e. Typically, it is selected in the range of 0.1 to 1.5 mm.

As described above, the optical recording medium according to this embodiment is configured.

Next, a method of manufacturing the optical recording medium configured as described above will be described. Here, first, an injection molding apparatus used for molding the first disk substrate 1 and the second disk substrate 2 which constitute the optical recording medium according to the embodiment will be described. In FIG.
1 shows an injection molding apparatus according to one embodiment.

That is, as shown in FIG. 4, the injection molding apparatus 10 for molding this disk substrate is composed of a stationary mold plate 11
The movable mold 14 incorporated in the movable mold plate 13 is fixed to the fixed mold 12 and the movable mold 14 is disposed so as to face each other. Then, when the fixed mold 12 and the movable mold 14 abut against each other, a molding cavity 16 is formed between the fixed mold 12 and the movable mold 14. This molding cavity 16
Has a shape corresponding to the disk substrate to be molded (the first disk substrate 1 and the second disk substrate 2).
The surface of the fixed mold 12 that forms one surface of the molding cavity 16 is a mirror surface that has been subjected to mirror finishing. Further, a cooling pipe 12 a is provided inside the fixed mold 12, and a cooling pipe 14 a is provided inside the movable mold 14.

An insertion hole 12b is formed at the center of the fixed mold 12 in the injection molding apparatus 10 shown in FIG. In the insertion hole 12b, a fixed bush 17 having a substantially annular cylindrical shape is inserted and provided. A sprue bush 18 is provided so as to fit into the fixed bush 17.

The sprue bush 18 has an annular shape, and an injection hole 19 is provided along the center axis of the annular shape. The injection hole 19 is used to fill a molding cavity 1 with a synthetic resin material such as a molten polycarbonate resin supplied from an injection device (not shown).
6 is configured to be able to flow into the inside. That is, the tip side of the sprue bush 18 is configured to face the inside of the molding cavity 16.

The molding cavity 1 of the fixed mold 12
A stamper 20 is mounted on the surface of the mold constituting the mold 6, that is, on the surface facing the movable mold 14. The stamper 20 is formed in a disk shape (planar annular shape) having a center hole 20a at the center. This stamper 20
Is for forming a concavo-convex pattern corresponding to an information signal or a pre-groove forming a recording track on a disk substrate. The inner peripheral portion of the stamper 20 is configured to be supported by a cylindrical stamper inner peripheral holder (not shown) at the peripheral edge of the center hole 20a. On the other hand, the outer peripheral portion of the stamper 20 is configured to be supported on the outer peripheral edge of the disk by the outer peripheral ring 21. Then, the stamper 20 is fixed to the fixed mold 12 by the stamper inner peripheral holder and the outer peripheral ring 21.
Attached to. Specifically, the outer peripheral ring 21
The thickness of the stamper 20 is increased by pressing the outer peripheral portion of the stamper 20 against the molding cavity 16 side of the fixed mold 12 by a land portion 21b provided in a convex shape on the uppermost edge of the inner peripheral ring portion 21a. The outer peripheral ring portion 21 c is attached to the fixed mold 12 using bolts 22. A stamper inner peripheral holder (not shown) for supporting the peripheral edge of the center hole 20a of the stamper 20 is fitted on the outer peripheral side of the fixed bush 17, and the molding cavity 1 of the sprue bush 18 is formed.
6 and is attached to the fixed mold 12.

On the other hand, an insertion hole 14 c is formed at the center of the movable mold 14. In the insertion hole 14c of the movable mold 14, a cylindrical eject sleeve 23 is inserted and provided. This eject sleeve 23
Is configured to be able to advance and retreat with respect to the molding cavity 16 and is supported by the movable mold 14. The eject sleeve 23 has a front end face facing the molding cavity 16,
It is slightly inserted into the movable mold 14. A cylindrical gate cut piston 24 is fitted inside the cylinder of the eject sleeve 23. The gate cut piston 24 has a front end face facing the molding cavity 16 slightly projecting from the front end face of the eject sleeve 23.

The injection molding apparatus 10 is configured as described above. In the injection molding apparatus 10, the fixed mold 12, the movable mold 14, and the outer ring 2
1 forms the molding cavity 16. That is, the respective outer peripheral portions of the first disk substrate 1 and the second disk substrate 2 to be molded are defined by the outer peripheral ring 21 of the outer peripheral portion of the molding cavity 16.
In this embodiment, the molding cavity 16 has the shape of the first disk substrate 1 shown in FIG. 2A, and the outer peripheral portion of the movable die 14 on the bonding surface 1 a of the first disk substrate 1. Is provided with a concave portion transfer convex portion 14b. This concave portion transfer convex portion 14
“b” is provided in a ring shape on the outer peripheral portion of the surface of the movable mold 14 that forms the molding cavity 16, and is provided in a stepped shape. Then, the first portion 14b for concave portion transfer is used to form the first portion.
The concave portion 1d of the disk substrate 1 is formed.

Next, an injection molding method for the first disk substrate 1 using the injection molding apparatus 10 configured as described above will be described.

That is, first, the fixed mold 12 and the movable mold 14 are abutted against each other to bring the mold 15 into a clamped state, and the molding cavity 16 is formed.

Next, in a state where the injection nozzle (not shown) is positioned on the sprue bush 18, molten resin such as molten PC resin is injected from the injection nozzle into the injection hole 19.
Is injected into the molding cavity 16.
Then, the molten resin is filled in the molding cavity 16. Thereafter, the filled molten resin is radiated and solidified. At this time, fine irregularities such as data recording pits or pregrooves formed on the surface of the stamper 20 are transferred to the solidified resin, and an information recording area on the first disk substrate 1 is formed. On the other hand, the surface facing the stamper 20 of the movable mold 14 forms the bonding surface 1a of the first disk substrate 1. In addition, the concave transfer protrusions 14b in the movable mold 14 are transferred to the outer peripheral portion of the resin formed in a predetermined disk substrate shape, and the concave portions 1d are formed in the outer peripheral portion of the bonding surface 1a of the first disk substrate 1. Is done.

At this time, the outer peripheral ring 21 and the movable mold 14
Resin enters the gap 25 between
A burr 1 e is formed on the outer peripheral edge of the disk substrate 1. As described above, burrs 1 e are generated on the outer peripheral edge of the first disk substrate 1, but since the concave portions 1 d are also formed, the burrs 1 e greatly protrude from the bonding surface 1 a of the first disk substrate 1. Can be prevented, and the amount of protrusion can be reduced.

After the information recording area is formed as described above and the resin is solidified, the gate cut piston 24 is pushed out in a direction to enter the inside of the molding cavity 16 and is projected. As a result, a hole is formed in the center of the solidified resin, and the center hole 1b in the first disk substrate 1 is formed.
Is formed. After that, the mold 15 is opened, the release air is supplied, and the eject sleeve 23 is made to protrude from the movable mold 14, thereby releasing the molded first disk substrate 1 from the movable mold 14.

As described above, the molding of the first disk substrate 1 according to this embodiment is performed.

Next, by a physical vapor deposition (PVD) method such as a sputtering method, a metal film having a desired laminated structure is formed on the main surface 1c of the first disk substrate 1 on which fine irregularities are formed. I do. As a result, the information signal portion 4 including the metal film having the unevenness and the laminated structure is formed.

Next, the light transmitting layer 5 is formed on the main surface 1c of the first disk substrate 1 so as to cover the information signal section 4 by using a predetermined bonding apparatus. As a result, a single-plate-shaped first disc before lamination, which constitutes the lamination type optical recording medium according to the embodiment, is manufactured.

The method of forming the first disk substrate 1 and the method of manufacturing the first disk by the injection molding method described above are the same as the method of forming the second disk substrate 2 and the second disk substrate.
The same applies to the method of manufacturing the second disk using the disk substrate 2 described above, and thus the description of the method of forming the second disk substrate 2 and the method of manufacturing the second optical disk will be omitted. When manufacturing a so-called single-sided recording type optical recording medium in which the bonded optical recording medium as a final product is a recording type having only one surface, an information signal area is provided as a second disk. A single-sided recording type optical recording medium is manufactured by using a smooth plate (dummy disk) that has not been subjected to this process and bonding the first disk and the dummy disk via a photocurable resin.

At least one of the bonding surfaces 1a and 2a of the first optical disk and the second optical disk manufactured as described above is coated with a photocurable resin such as an ultraviolet curable resin. Apply. Thereafter, the bonding surfaces 1a and 2a are opposed to each other, are matched with each other via a photocurable resin, and are pressed. Then, the photocurable resin is cured by irradiating the photocurable resin with light for curing, for example, ultraviolet rays. Thus, the adhesive layer 3 made of a photocurable resin is formed, and an optical recording medium such as a magneto-optical disk is manufactured according to this embodiment.

As described above, according to this embodiment, the concave portions 1d, 2d are respectively formed on the outer peripheral portions of the bonding surfaces 1a, 2a of the first disk substrate 1 and the second disk substrate 2, respectively. Due to the formation, the burrs 1e and 2e generated by the resin entering the gap 25 between the outer peripheral ring 21 and the movable mold 14 in the injection molding apparatus 10 are separated from the bonding surfaces 1a and 2a. Since it can be prevented from protruding significantly, it is possible to set the amount of protrusion from the bonding surfaces 1a, 2a to less than half the thickness of the adhesive layer 3. Also, the recess 1d,
By making 2d deeper, burrs 1e and 2e become
It can be prevented from being lower than the bonding surfaces 1a and 2a and protruding from these surfaces. This can prevent the burrs 1e and 2e from interfering with each other in bonding the first disk and the second disk, so that the thickness of the adhesive layer 3 is uniform over the entire surface of the optical recording medium. Can be Therefore, it is possible to prevent the occurrence of skew in an optical recording medium manufactured by bonding the other main surfaces (bonding surfaces 1a and 2a) on the opposite side to the side where the information signal portions 4 and 6 are provided. As a result, it is possible to obtain an optical recording medium having a high density and a large capacity and having improved optical characteristics and quality.

Further, according to the method of manufacturing an optical recording medium according to this embodiment, the first disk substrate 1 and the second disk
Since it is not necessary to perform a burr removal step performed in accordance with the generation of burrs 1e and 2e on the disk substrate 2, the manufacturing process of the optical recording medium can be simplified, and the burr is generated when the burr is removed. Since no dust or the like is generated, it is possible to manufacture a clean, highly reliable optical recording medium.

Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above embodiment, and various modifications based on the technical idea of the present invention are possible. .

For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as needed.

In the above-described embodiment, the first
The recess 1d whose cross section along the radial direction has a triangular shape is formed in the outer peripheral portion of the bonding surface 1a of the disk substrate 1 of FIG. As shown in FIG. 5B, the outer peripheral portion of the bonding surface 1a can be formed as a step-like stepped portion 1f. As shown in FIG. 5B, the outer peripheral portion of the bonding surface 1a is formed into a tapered portion 1g. It is also possible to use Further, as shown in FIG. 6, the portion of the bonding surface 1a on the inner peripheral portion of the concave portion 1d on the side opposite to the side where the burr 1e is generated in the radial direction of the first disk substrate 1 is formed into a curved surface. It is also possible to form the curved surface portion 1h. As described above, when the curved surface portion 1h is formed on the inner peripheral side of the concave portion 1d on the outer peripheral portion of the bonding surface 1a, it is separated from the movable mold 14 of the injection molding apparatus 10. When the mold is formed, the mold is easily released, so that the non-uniformity of the release can be improved.

[0081]

As described above, according to the present invention, in an optical recording medium manufactured by laminating two substrates, warpage is prevented and the thickness of the adhesive layer used for lamination is reduced. The non-uniformity of the optical recording medium can be avoided, whereby the signal characteristics and quality of the optical recording medium can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical recording medium according to an embodiment of the present invention.

FIGS. 2A and 2B are a cross-sectional view and a plan view showing a disk substrate constituting an optical recording medium according to an embodiment of the present invention.

FIG. 3 is a sectional view showing the vicinity of a burr of a disk substrate constituting the optical recording medium according to the embodiment of the present invention;

FIG. 4 is a sectional view showing an injection molding apparatus according to one embodiment of the present invention.

FIG. 5 is a sectional view showing another example of the disk substrate according to the embodiment of the present invention;

FIG. 6 is a sectional view showing another example of the vicinity of the burr of the disk substrate according to the embodiment of the present invention;

FIG. 7 is a cross-sectional view illustrating a bonded optical disk according to the related art.

FIG. 8 is a cross-sectional view showing an injection molding apparatus according to the related art.

FIG. 9 is a cross-sectional view for explaining a problem of an injection molding apparatus and a disk substrate according to the related art.

FIG. 10 is a cross-sectional view for explaining a problem of a bonded optical disk according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st disk substrate, 1a, 2a ... Bonding surface, 1b, 2b ... Center hole, 1c, 2c
... Main surface, 1d, 2d ... Recess, 1e, 2e ...
Burr, 1f: Step, 1g: Taper, 1h
..Curved surface portion, 2 ... second disk substrate, 3 ... adhesive layer, 4,6 ... information signal portion, 5,7 ... light transmitting layer, 10 ... injection molding device, 11 ... fixed side mold plate,
12: fixed mold, 12a: cooling tube, 12b ...
Insertion hole, 13: movable mold plate, 14a: cooling tube, 14b: concave transfer projection, 14: movable mold, 14c: insertion hole, 15: gold Mold, 16 ...
Molding cavity, 17 ... fixed bush, 18 ...
・ Sprue bush, 19 ・ ・ ・ Injection hole, 20 ・ ・ ・ Stamper, 20a ・ ・ ・ Center hole, 21 ・ ・ ・ Outer peripheral ring, 2
1a: inner peripheral ring portion, 21b: land portion, 21
c ... outer peripheral ring part, 22 ... bolt, 23 ...
Eject sleeve, 24: gate cut piston, 25: gap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 17:00 B29L 17:00 (72) Inventor Masahiro Owada 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Katsuya Tozaki 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 4F202 AG03 AH79 AM35 CA11 CB01 CK11 CK85 5D029 KB12 RA08 RA35 RA45 5D121 DD05 DD18

Claims (21)

[Claims] 1. A first substrate provided with an information signal portion configured to be capable of recording / reproducing information signals on one main surface thereof, and the other main surface of the first substrate opposite to the side provided with the information signal portion. And the second
An optical recording medium having a structure in which the first substrate is bonded to the other substrate, wherein an outer peripheral portion of the other main surface of the first substrate is provided with a portion thinner than other portions of the first substrate; An optical recording medium, characterized in that a thinner portion than another portion of the second substrate is provided on an outer peripheral portion of a surface of the second substrate to be bonded to the first substrate. 2. The optical recording apparatus according to claim 1, wherein an information signal portion is provided on one main surface of the second substrate opposite to a surface to be bonded to the first substrate. Medium. 3. A portion thinner than the other portion of the first substrate is configured to be thinner by 10 μm or more and 200 μm or less than the other portion, and a portion thinner than the other portion of the second substrate. 2. The optical recording medium according to claim 1, wherein the optical recording medium is configured to be thinner than the other portion by 10 μm or more and 200 μm or less. 4. The method according to claim 1, wherein the outer peripheral portion includes the first substrate and / or the first substrate.
Or, from the outer peripheral end of the second substrate toward the inside, the.
2. The optical recording medium according to claim 1, wherein the distance is within a range from 1 mm to 1.5 mm. 5. The optical recording medium according to claim 1, wherein said first substrate and said second substrate have a planar annular shape. 6. The optical recording medium according to claim 5, wherein portions of the first substrate and the second substrate that are thinner than the other portions are provided in a belt shape. 7. The flat substrate according to claim 5, wherein portions of the first substrate and the second substrate which are thinner than the other portions are provided all around the outer periphery of the flat annular shape. Optical recording medium. 8. A method for manufacturing an optical recording medium, comprising the steps of: after manufacturing two substrates, bonding the respective bonding surfaces of the two substrates to each other via an adhesive layer. A method for manufacturing an optical recording medium, wherein a portion thinner than other portions of the substrate is formed on an outer peripheral portion of a bonding surface. 9. The method according to claim 1, further comprising the step of forming an information signal portion on the main surface of the substrate opposite to the bonding surface, the information signal portion being capable of recording and / or reproducing information signals. 9. The method for producing an optical recording medium according to item 8. 10. An information signal portion configured to record and / or reproduce an information signal is formed on a main surface of one of the two substrates opposite to the bonding surface. 9. The method for manufacturing an optical recording medium according to claim 8, further comprising the step of: 11. A part thinner than the other part of the substrate,
9. The method for manufacturing an optical recording medium according to claim 8, wherein the optical recording medium is formed to be thinner by 10 μm or more and 200 μm or less than the other portions. 12. The optical recording medium according to claim 8, wherein the outer peripheral portion is within a range of 0.1 mm or more and 1.5 mm or less from an outer peripheral end to an inner peripheral side of the substrate. Production method. 13. The method for manufacturing an optical recording medium according to claim 8, wherein said substrate has a planar annular shape. 14. The method of manufacturing an optical recording medium according to claim 13, wherein a portion of said substrate that is thinner than said other portion is formed in a band shape. 15. The method for manufacturing an optical recording medium according to claim 13, wherein a portion of said substrate that is thinner than said other portion is formed on the entire circumference of said planar annular outer peripheral portion. 16. A substrate molding die having a mold capable of forming a cavity and capable of being opened and closed, wherein a resin is injected into the cavity of the mold to form a substrate. Of one of the molds constituting the cavity,
A mold for molding a substrate, wherein a convex portion is provided on an outer peripheral portion of a surface constituting the cavity. 17. The mold for molding a substrate according to claim 16, wherein said convex portion is raised by 10 μm or more and 200 μm or less as compared with the other portion of said one mold. 18. The method according to claim 18, wherein the outer peripheral portion is 0.1 mm or more from the outer peripheral end of the formed cavity toward the inner peripheral side.
17. The distance of not more than 5 mm.
A mold for molding a substrate as described in the above. 19. The mold for molding a substrate according to claim 16, wherein said cavity has a disk shape. 20. The substrate molding die according to claim 19, wherein said convex portion is provided in a strip shape on a surface constituting said cavity of said one die. 21. The substrate molding die according to claim 19, wherein the convex portion is provided on the entire periphery of an outer peripheral portion of a surface constituting the cavity of the one die. .