JP2002074756A - Optical disk, method for manufacturing the same and molding die for disk molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk, a method for manufacturing the disk and a molding die for the disk molded body in which improvement in the quality of a laminated optical disk, improvement in the production yield and decrease in the production cost are realized. SOLUTION: A recess is formed in the innermost peripheral part on the recording face of at least one disk molded body of two disk molded bodies to be laminated with the recording faces opposing each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DVD (Digital
The present invention relates to an optical disk formed by laminating two disk molded bodies used for tal versatile disc), a method for manufacturing the same, and a molding die for the disk molded body.

[0002]

2. Description of the Related Art In recent years, with the rapid increase in the amount of information processing,
Optical discs that have a tremendously large storage capacity and can cope with digitization have attracted much attention from various industries. Among them, DVDs having a structure in which a storage unit is sealed in a synthetic resin material layer and not exposed to the outside are rapidly spreading as optical disks capable of storing data stably. This DVD is manufactured by bonding two disk molded bodies with their storage surfaces facing each other with an adhesive. An example of a conventional disk molded body and such a bonding method in such a bonding type optical disk will be described with reference to FIGS.

FIG. 4 is a sectional view of a conventional apparatus for molding a disk, FIG. 5 is a sectional view of a conventional disk, and FIG. 6 illustrates a conventional method of bonding two disk bodies. FIG. In FIG. 4, a conventional disk molded body has a transparent synthetic resin material (hereinafter, referred to as a transparent resin material) formed in a gap 5 formed when the upper mold 10 and the lower mold 2 that can be opened are clamped.
(Hereinafter simply referred to as a resin material). A stamper 3 for imprinting information as irregularities 8 on a disk molded body is fixed to the upper die 10 by a stamper holder 9 and an outer stamper support member 14. Further, a sprue 6 is formed as a conductive hole for injecting a resin material along the central axis 4 of the upper mold 10.

[0004] A cylindrical gate cutter 11 is attached to the lower mold 2 at a central portion via a sleeve 12 so as to be vertically movable along a central axis 4. Further, the lower die 2 is provided with an eject rod 7 that can slide up and down with respect to the gate cutter 11. Note that, at the time of molding the disk molded body, the eject rod 7 is drawn into the inside of the gate cutter 11, and forms a recess called a slag well 13 so as to store an excessively filled resin material.

[0005] A conventional method for forming a disk molded product will be described. The upper mold 10 and the lower mold 2 are clamped in a predetermined relationship, and a resin material which has been heated and flowed into the gap 5 formed therebetween is injected and filled through the sprue 6. The filled resin material is cooled, and the gate cutter 11 is moved upward during or after cooling to punch out the resin material at the center. After cooling and hardening, the mold is opened, and the disk molded body molded by the eject rod 7 is pushed up and separated from the lower mold 2. The disk molded body is transferred from the lower mold 2 to the outside by a take-out machine (not shown).

[0006] As shown in FIG. 5, the formed disk molded body 20 has an information recording surface 22 with irregularities 8 on which information is engraved.
And an inclined portion 24 which becomes a pool portion of the adhesive when being bonded to the outer periphery. In addition, when the center portion is punched by the gate cutter 11, the center hole 2
Burr a often occurs at the portion of 0a.

Next, with reference to FIG. 6, a description will be given of a method of laminating and sticking two disc molded bodies produced by the above-mentioned conventional apparatus. In FIG. 6, in order to simplify the drawing, the irregularities of the recording portion 21 of each disk molded body are shown in a small number and large. In addition, the recording unit 21 is 2
There is a type in which only one of the disk molded bodies is formed.

The recording surfaces 22, 22 of the two disk molded bodies 20, 20 are spaced apart from each other, and the positioning pins 3
1 is inserted into the center hole 20a and assembled. Next, a dispenser 32 is inserted into a gap between the two disc molded bodies 20 and 20.
The tip 33a of the nozzle 33 is inserted into each of the desk moldings 2
The adhesive 19 is injected into the inner peripheral side of the recording unit 21 of 0, 20 and the dispenser 32 is pulled out from the gap. afterwards,
The two disc molded bodies 20, 20 are pressed against each other in the thickness direction thereof, and are communicated in a longitudinal direction from several places on the side surfaces of the positioning pins 31 by a known suction device 35 via a suction pipe 34 provided therein. Excess adhesive 19 is sucked to spread the adhesive 19 evenly around the inner peripheral portion of the disk molded body. Next, so-called spin coating, in which the disc molded body is rotated at a high speed around the central axis 31 and the adhesive is applied while being diffused from the inner peripheral portion to the outer peripheral portion, is performed.
Then, the adhesive applied between the recording surfaces 22 of the two disk molded bodies is cured by irradiating the adhesive with ultraviolet rays to complete the bonding step.

[0009]

However, the following problems occur in the optical disk manufactured using the conventional disk molded body. The first problem is that when the disc molded body 20 is rotated at a high speed in the bonding step and the adhesive 19 is applied by spin coating, the adhesive flowing out from the inner peripheral portion of the disc molded body is located above or below the optical disc. This is to adhere to the surface, and the cleanliness of the surface of the optical disk is reduced.
The second problem is that if the injection amount of the adhesive is reduced to prevent the adhesive 19 from flowing out, the thickness of the spin-coated adhesive applied layer becomes uneven and the quality of the DVD deteriorates. It is. The third problem is that, when manufacturing the disk molded body, the upper and lower disk molded bodies 20, 20a and a generated when the center hole is punched out by a gate cutter interfere with each other, and a gap between the burrs a and a. In the bonding process, the burrs a create a gap of a predetermined size or more in the bonding surface near the center hole of the disk molded bodies 20, and the thickness of the adhesive layer becomes uneven. It is.

[0010] An object of the present invention is to reduce the cleanliness of the disk surface due to the adhesion of the adhesive, to make the thickness of the adhesive layer non-uniform due to the shortage of the adhesive, and to prevent the generation of gaps on the joining surface of the disk molded body due to burrs. Another object of the present invention is to provide an optical disk capable of improving the quality of an optical disk, improving the production yield, and reducing the manufacturing cost, a method for manufacturing the optical disk, and a mold for molding a disk molded body.

[0011]

An optical disk according to the present invention comprises two disk-shaped disk molded bodies having at least one surface on which information is recorded and having a through hole at the center of rotation. An optical disk prepared by bonding both disc molded bodies by bonding in a state where the surfaces on which are recorded are opposed to each other and the central axes of the through holes are aligned, wherein at least one of the two disc molded bodies is bonded. An annular concave portion is provided on the innermost peripheral portion of the mating surface.

According to the optical disk having this configuration, the adhesive can be stored in the concave portion provided on the innermost circumference of the bonding surface of the disk molded body. As a result, it is possible to prevent the adhesive from flowing out and prevent the adhesive from adhering to the surface of the optical disk. Further, since the outflow of the adhesive can be prevented, it is not necessary to reduce the injection amount of the adhesive, and the unevenness of the thickness of the adhesive layer can be prevented.

In the optical disk having the above-mentioned structure, if the depth of the concave portion is such that burrs generated during the molding of the disk molded body do not interfere with each other, it is possible to prevent the formation of a gap between the joining surfaces of the disk molded body due to the burrs. Furthermore, if the recesses having the same depth are formed in two disk molded bodies, one type of disk molded body can be used, and the manufacturing cost can be reduced.

According to a method of manufacturing an optical disk of the present invention, at least one surface has a surface on which information is recorded, and two disk-shaped disk molded bodies having a through hole at the center of rotation are formed on the surface on which the information is recorded. Are opposed to each other, and the two disc molded bodies are adhered to each other by bonding in a state where the center axes of the through holes are aligned with each other. An annular concave portion is provided in the peripheral portion, and the adhesive is stored in the concave portion so that the adhesive does not protrude to the surface of the optical disk.

According to this method of manufacturing an optical disk, since the adhesive is accumulated in the concave portion, the deterioration of cleanliness due to the outflow of the adhesive and the unevenness of the thickness of the adhesive layer due to the insufficient amount of the adhesive occur. Can be prevented. As a result, the occurrence of the above-described failure can be prevented without strictly controlling the injection amount of the adhesive, thereby simplifying the manufacturing method.

In the above manufacturing method, if the depth of the concave portion is set to a depth at which burrs generated during molding of the desk molded body do not interfere with each other, the thickness of the adhesive in the bonding step can be made uniform.

In the mold for molding an optical disk molded article of the present invention, the thickness of the inner peripheral portion of the molding surface of one of the pair of disk molding dies is formed so as to form the concave portion in the disk molded body. It is characterized by being thicker than other parts.

According to this molding die, the thick portion of the inner peripheral portion is transferred to the disk molded body, so that a concave portion is formed in the inner peripheral portion of the disk molded body. Further, burrs generated when the center hole is punched are also confined in the recess.
As a result, it is possible to prevent the adhesive from flowing out to the surface of the optical disk in the bonding step, and to prevent the adhesive from having a nonuniform film thickness due to interference of burrs.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an optical disk and a method of manufacturing the same according to the present invention, and a mold for molding a disk molded body will be described below with reference to FIGS. Also, the optical disk in this embodiment will be described as an optical disk of a type in which a recording unit is formed on both of two disk forming bodies.

Embodiment 1 FIG. 1 is a sectional view of an optical disc according to Embodiment 1 of the present invention. FIG. 2 is an enlarged sectional view of the inner peripheral portion of the optical desk. In FIG. 1, in order to simplify the drawing, the unevenness of the recording portion 21 of each disk molded body is shown as being small and large. In FIG. 1, the optical disk of the first embodiment includes two disk molded bodies 100, 1
00 with the recording portion forming surfaces facing each other, and
0a are aligned with the center axis of the UV curable adhesive 191.
And formed by bonding. A concave portion 104, which is a feature of the present invention, is formed around the center hole 100a on the recording portion forming surface, which is the innermost peripheral portion of each disk molded body 100.

Referring to FIG. 2, a method of attaching the disk molded body of the first embodiment will be described. The recording part forming surfaces 102 of the two disk molded bodies 100, 100,
102 are spaced apart from each other and the positioning pin is
0a and assemble. Two disc moldings 10
An adhesive 191 is injected around the center hole 100a of each of the disc molded bodies 100, 100 by a dispenser into the gap between 0 and 100. Then, the two disk molded bodies 10
0 and 100 are pressed in the thickness direction, and the adhesive is sucked by a known suction device in the same manner as in the conventional example to spread the adhesive uniformly on the inner peripheral portion of the disk molded body. Next, the disk moldings 100, 100 are rotated at high speed around the central axis, and the adhesive 191 is applied to the lower disk molding 10
The adhesive is diffused in the direction from the inner peripheral part to the outer peripheral part and the adhesive is applied by spin coating. Then, the adhesive applied between the recording surfaces 22, 22 of the two disk molded bodies 100, 100 is irradiated with ultraviolet rays to be cured, thereby completing the bonding step.

As shown in FIG. 2, the excess adhesive 191 that is excessively injected is applied to the center hole 10 of the disc molded body 100.
0a, is stored in a concave portion 104 formed in an annular shape around
It does not flow out and adhere to the surface of the disk molded body 100. Further, the burrs a generated during the molding of the disk molded body 100 are also accommodated in the recesses 104, so that the thickness of the adhesive layer does not become nonuniform due to interference during bonding.

<Embodiment 2> FIG. 3 is a sectional view of an apparatus for forming a disk molded body according to Embodiment 2 of the present invention. The same parts as those in the conventional example will be described with the same reference numerals. In FIG. 3, the disk molded body 100 of the second embodiment is heated to the gap 5 formed when the upper mold 10 and the lower mold 2, which can be opened, are clamped in a predetermined relationship to be in a fluid state. It is formed by injecting the resulting resin material. A stamper 300 for imprinting information as irregularities 8 on the disk molded body 100 is fixed to the upper die 10 by a stamper holder 9 and an outer stamper support member 14.

The innermost periphery of the stamper 300 has a predetermined depth in the disk molded body 100 (40 to 200 μm in the case of a type in which an information recording recess is formed only on one side of the disk, Is 20 to 100 μm in the case of a type in which a convex portion 105 is formed.) The convex portion 105 for forming the concave portion 104 is formed. Further, a sprue 6 for injecting a resin material along the central axis 4 of the upper mold 10 is formed. A gate cutter 11 is attached to the lower mold 2 at a central portion via a sleeve 12 so as to be movable along the central axis 4. Further, the lower die 2 is provided with an eject rod 7 that can slide up and down with respect to the gate cutter 11. During the molding of the disc molded body 100, the eject rod 7 is
A recess called a slag well 13 is formed so that the resin material which is drawn into the inside and is overfilled is stored.

A method of forming a disk molded body according to the second embodiment will be described. The upper mold 10 and the lower mold 2 are clamped in a predetermined positional relationship, and the sprue 6 is inserted into a gap 5 formed between them.
Then, the resin material which has been heated to a fluid state is injected and filled. Cool the filled resin material and when it is near the end of cooling,
Alternatively, after cooling, the gate cutter 11 is moved upward, and the center hole 100 is formed by punching out the resin material at the center. After cooling and curing the resin material, the mold is opened and the disk molded body 100 molded by the eject rod 7 is pushed up and separated from the lower mold 2. The disk molded body 100 is transferred from the lower mold 2 to the outside by a take-out machine (not shown).

As shown in FIG. 1, the molded disk 100 has a recording section in which information is formed on the information recording surface 22 by embossing information, and a concave section 104 around a center hole 100a which is the innermost peripheral section. And an inclined portion 24 on the outer periphery that becomes a pool portion of the adhesive when two pieces are bonded to each other. When the center hole 100a is punched by the gate cutter 11, a slight burr a (about 20 μm to about 100 μm in height) may be generated. However, as shown in an enlarged manner in FIG.
It arises from the bottom of the recess 104 recessed a certain level from the surface of the zero. Therefore, the burr a has a thickness of 2
The shape is accommodated between the inside and the inside of the adhesive layer 191 of 5 to 50 μm. Therefore, as in the prior art, both disc molded bodies 10
The tips of the burrs a, a of 0, 100 do not interfere (collide with each other), so that the thickness of the adhesive layer 191 between the two disk molded bodies 100, 100 is not made uneven.

The injected adhesive is applied to the annular recess 1.
Since the adhesive is accumulated on the surface of the optical disk 04, it is possible to prevent the quality of the optical disk from deteriorating due to the adhesion of the adhesive flowing out to the surface. Therefore,
In order to prevent the adhesive from flowing out to the outside, it is possible to reduce the time and the manufacturing cost, which have been required to strictly adjust the injection amount of the adhesive.

In the first and second embodiments, an optical disk using two disk formed bodies having recesses of the same depth has been described. However, a recess having a depth twice as large as that of the other disk formed body is formed on one disk formed body. The same effect can be obtained for the optical disk of the type described above.

[0029]

As described in detail in the above embodiments, the following effects can be obtained according to the present invention. That is, the concave portion provided on the innermost peripheral portion of the disk molded body can suppress the adhesive from flowing out. As a result, it is possible to prevent the quality of the optical disk from deteriorating due to the adhesion of the adhesive that has flowed out, and it is not necessary to strictly adjust the amount of the injected adhesive, thereby reducing the manufacturing cost. Also, regarding the occurrence of a defect in which the thickness of the adhesive layer is not uniform due to the interference of burrs generated during the molding of the disc molded body, an adhesive layer having a uniform thickness is formed by housing the burrs in the recesses. Can be eliminated.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical disc according to a first embodiment of the present invention. However, in order to mainly explain the cross-sectional structure near the center, the dimensional relationship in the drawings is shown differently from the actual one.

FIG. 2 is a partially enlarged cross-sectional view near the center hole of the optical disc according to the first embodiment of the present invention.

FIG. 3 is a sectional view of an apparatus for molding a disk molded body according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional disk molding device forming apparatus.

FIG. 5 is a cross-sectional view of a conventional optical disc.

FIG. 6 is a cross-sectional view illustrating a state where an adhesive is injected in a step of bonding two molded discs in a conventional optical disc.

[Explanation of symbols]

 2 Lower die 3 Stamper 4 Center axis 5 Void 6 Sprue 7 Eject rod 8 Recording part unevenness 9 Stamper holder 10 Upper die 11 Gate cutter 12 Sleeve 13 Slug well 14 Outer peripheral stamper holder 19 Adhesive 21 Recording part 22 Recording surface 24 Inclined part 31 Positioning pin 32 Dispenser 33 Nozzle tip 34 Suction pipe 35 Suction device 100 Disc molded body 100a Center hole 104 Depression 105 Projection 141 Optical disk 191 Adhesive a Burr

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/26 G11B 7/26 // B29L 17:00 B29L 17:00 (72) Inventor Maki Terada Osaka 1006 Kadoma Kadoma Matsushita Electric Industrial Co., Ltd. AA07 DD18 EE22 FF04

Claims (7)

[Claims] 1. A disk-shaped disc having two disc-shaped bodies having at least one surface on which information is recorded and having a through hole at the center of rotation, wherein the surfaces on which the information is recorded face each other,
An optical disk produced by bonding the two disk molded bodies by bonding in a state where the center axes of the through-holes are aligned with each other, wherein at least one of the two disk molded bodies has an annular innermost peripheral surface. An optical disc characterized by having a concave portion. 2. The optical disk according to claim 1, wherein the depth of the concave portion is such that burrs (a) generated during molding of the disk molded body do not interfere with each other. 3. The optical disk according to claim 2, wherein the concave portions having the same depth are formed in two of the disk molded bodies. 4. At least one surface has a surface on which information is recorded, and two disc-shaped disc molded bodies having a through hole at the center of rotation are faced to each other with the information recording surfaces facing each other,
In the bonding step of bonding the two disk molded bodies by bonding with the center axes of the through holes aligned, an annular concave portion is formed at the innermost peripheral portion of at least one bonding surface of the two disk molded bodies. A method for manufacturing an optical disk, comprising: providing an adhesive in the recess so that the adhesive does not protrude to the surface of the optical disk. 5. The film thickness of the adhesive in the bonding step is made uniform by setting the depth of the concave portion to a depth at which burrs generated during molding of the desk molded body do not interfere with each other. Item 5. The method for manufacturing an optical disk according to Item 4. 6. A thickness of an inner peripheral portion of a molding surface of one disk molding die is made larger than a thickness of another portion of the disk molding so as to form the concave portion in at least one disk molding. A mold for molding an optical disk molded body, characterized in that: 7. The thickness of the inner peripheral portion of each molding surface of each disk molding die is adjusted so that the recesses having the same depth are formed in two disk moldings. A mold for molding an optical disc molded body characterized in that the thickness is larger than the thickness of the portion.