JP2002140839A - Optical disk, manufacturing method of the same, metallic die and press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk using a thin injection molded substrate which can be used ton the handy movie camera of small mass eccentricity, and a laminated optical disk by using the thin injection molded substrate. SOLUTION: This laminated optical disk includes a single-plate injection molded substrate having a thickness of 0.8 mm or less, an outer diameter of which is 100 mm or less, and mass eccentricity of which is 0.1 g/cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk using a thin injection molded substrate, a method and an apparatus for manufacturing an optical disk.

[0002]

2. Description of the Related Art In recent years, a magneto-optical disk or a digital persatile disk (hereinafter referred to as a DVD) suitable for recording and reproduction of audio and image information has been used as an optical recording carrier having a large recording capacity and high convenience. I have. Such an optical record carrier is composed of a recording film, a reflective film, a protective film and the like on a resin substrate such as polycarbonate.

[0003] Further, as the recording capacity of the optical disk increases, the wavelength of the laser becomes shorter and the numerical aperture NA of the objective lens increases, so that the optical disk substrate is required to be thinner.
In particular, in the case of DVD, the thickness of the single-plate substrate is set to 1.2
mm to 0.6 mm, shorten the optical path length of the laser, and correct the allowable value for warpage (Nikkei Electronics 199
February 27, 5 issue No. 630) A configuration is adopted in which two single-plate disks are bonded together with an adhesive.

[0004] These DVDs are used for handling audio, video and data in a stationary recording / reproducing apparatus. However, DVD-RAM book version 2.
One standard is being adopted as a handy type movie. This is a DVD-RAM
(Outer diameter φ120 mm, single-sided recording capacity 4.7 GB)
B) The DVD-RAM is a rewritable removable optical disk using a phase change recording medium.

Hitherto, there have been CDs and MDs for recording and reproducing music as optical disks used outdoors. C
D is a read-only (ROM) type, and MD is a rewritable type using a magneto-optical recording film as a recording medium. The CD
And the MD has a track pitch of 1.6 μm, a laser wavelength of 780 nm, and a single-plate substrate thickness of 1.2 mm.
The recording density was not so tight, and the data handled was audio only.

[0006] On the other hand, the DVD-
The RAM is a laminated optical disk having a track pitch of 0.615 μm, a laser wavelength of 650 nm, and a single-plate substrate thickness of 0.6 mm, thereby achieving high-density recording and large recording capacity. Video data. Therefore, it is difficult to follow the tracking servo, and when the drive is used in a vibrated state, a problem such as tracking loss is further increased.

[0007] The weight imbalance that the spindle of the drive receives from the inner diameter of the disk when the disk rotates is called the eccentricity. Φ80mm DVD-R
Since the AM is a bonded disk, the eccentricity tends to be larger than that of a disk formed of a single-plate substrate for the reason described later.

[0008] According to the DVD-RAM standard, book
gravity 2.1 is Dynamic
DVD with outer diameter Φ120mm as inbalance
≦ 0.01 g · m (≦ 1.0 g · cm) for RAM and ≦ 0.0045 g · m for DVD-RAM with outer diameter Φ80 mm
(≦ 0.45 g · cm). However, it has been found that a DVD-RAM disk having an outer diameter of Φ80 mm, even within this standard, can overwrite the spindle when recording a movie while moving the movie, thereby failing to perform normal recording and reproduction.

FIG. 6 shows a form of the DVD-RAM having an outer diameter of Φ80 mm.
This is also an exemplary form of a DVD in which two single-plate disks having a diameter of 1 mm are bonded together. In such a bonded optical disk, the recording signal surface on which the prepits and pregrooves are engraved on the substrate is bonded to each other, so that the recording incident surface by the laser is opposite to the bonding surface, and the recording incident surface for a DVD-RAM having an outer diameter of Φ80 m. On the side, a hard coat film 25 made of an ultraviolet curable resin is formed. On the recording signal surface, a recording film 22 provided by sputtering or vapor deposition, such as a reflection film or a phase change recording film, and a protective film 36, such as an ultraviolet curable resin for protecting the recording film from oxidation or the like, are sequentially laminated. ing. Further, these veneers are bonded together via an adhesive layer 29 made of a hot melt, an ultraviolet curing adhesive or the like.
In some cases, the adhesive and the protective film are integrated, and in some cases, the recording film is formed only on one side and a dummy substrate is provided on one side.

In the case of a DVD-RAM, the phase change film as a recording film is about 1 μm or less, but the protective film and the adhesive each have a thickness of several tens μm. The thickness of the single board is 1.2
mm compared to optical discs such as CDs, which have a single layer of protective film and hard coat film and no adhesive.
The thickness of the adhesive or the protective film is added to the disc, and the disc after lamination tends to have large thickness unevenness as the entire thickness. Therefore, the weight balance is deteriorated, and the eccentricity tends to increase.

The substrate is manufactured by an injection molding method using a plastic material represented by polycarbonate. The conceptual diagrams are shown in FIGS. FIG. 7 is a sectional view of a main part of the injection mold, showing a state in which the parting line 30, which is the mating surface of the fixed mold and the movable mold, is closed. The direction of gravity is, for example, the lower direction in the figure. Alignment of the fixed mold and the movable mold is performed by a guide ring 33 which is a ring-shaped tapered fitting, but there is also a guide post type mold which performs alignment by a cylindrical post and a bearing bush. The guide ring mold aligns with the circumferential guide, but the guide post mold aligns by line contact at a position distant from the cavity. Although inferior, it is considered that the parallelism when the cavity is opened is excellent.
The temperature of the fixed mold and the movable mold is controlled by cooling water flowing through the temperature control circuit 32.

The filling of the resin is performed as follows. In a state where the parting line 30 is closed or slightly opened, the molten resin is filled into the cavity 31 through the spool 10 from a nozzle tip of a molding machine (not shown), and at least one of a fixed mold and a movable mold is provided. Information of pre-grooves and pre-pits is transferred to a substrate by a stamper 11 attached to one side. In the case of a DVD having a thin single-plate substrate, it is necessary to smoothly fill the molten resin and reduce birefringence. A general method of forming a thin substrate is to increase the filling speed and open the cavity largely as shown in FIG. However, when the cavity is opened widely, in the case of the guide ring mold, the parallelism is impaired as described above, and the cavity thickness tends to be uneven within one circumference. In the case of the guide post mold, although there is no significant difference in the parallelism between the closed state and the open state of the cavity,
Similarly, it was difficult to maintain the cavity in parallel because the alignment accuracy in the closed state was difficult.
Due to these factors, one round of the thickness of the DVD substrate having a thickness of 0.6 mm tends to be larger than that of the substrate having a thickness of 1.2 mm. In the case of a thin substrate, the resin temperature is increased and the viscosity is reduced, and filling is performed, so that uneven cooling in the mold is emphasized, and the unevenness of the substrate cooling rate in one round becomes a factor of uneven thickness. . When the same unevenness occurs in one round of the plate thickness, the thinner the plate thickness, the greater the weight imbalance and the greater the eccentricity.

As shown in FIG. 9, the resin after filling is punched out of the inner diameter by a cut punch 12 which moves in conjunction with a piston (not shown) of the molding machine when in a molten state immediately after filling. The eccentricity of the outer diameter of the substrate with respect to the inner diameter of the substrate may be increased due to the eccentricity of the cut punch in the vertical and horizontal directions during driving. As described above, in the molding method for opening the cavity, the alignment accuracy of the fixed mold and the movable mold is easily deviated, so that misalignment of the inner diameter has become an important issue. The misalignment of the inner diameter also causes the load during the rotation of the spindle to become unbalanced, which causes the eccentricity to increase. From the above viewpoints, in the conventional thin substrate molding technology for DVDs and the like,
It is difficult to reduce the eccentricity of the outer diameter with respect to the thickness unevenness and the inner diameter, and it has been impossible to reduce the eccentricity of the single-plate substrate.

On the other hand, as a method of laminating a single-plate disc, there is a method of applying a hot-melt adhesive to the laminating surface side and bringing them into close contact with each other. In the case of a DVD-RAM disc having an outer diameter of Φ80 mM, the following method using screen printing is mainly used. The conceptual diagrams are shown in FIGS.
Shown in

First, an acrylic ultraviolet curable resin is applied on a sputter recording film by a spin coating method.
The protective film 36 is formed by irradiating ultraviolet rays as shown in FIG. Further, a slow-acting adhesive is applied to the bonding surfaces of the two single-plate disks by a screen printing method. As shown in FIG. 11, an epoxy adhesive 29 is accumulated on a printing screen 9 having a mesh structure as shown in FIG.
The film is formed by reciprocating 3 and exuding from the screen 9. The mesh portion formed on the screen plate has a donut shape, and an adhesive is applied only to that portion.
Mesh roughness, squeegee 13 speed, adhesive viscosity,
The thickness and distribution of the adhesive are controlled by Tg and the like.
Then, as shown in FIG. 13, after irradiating ultraviolet rays from above the adhesive to each of the single-plate disks, the reaction of the adhesive was started, and then, as shown in FIG. The core is also aligned via a pin with a small outer diameter 6. In this state, the two single disks are not completely integrated, and the warp is not corrected and the two disks are in a large state. Therefore, as shown in FIG.
Is applied by the press face plate 19 to which the pressure is applied to correct the warpage. The pressure applied to the press face plate is controlled by an air cylinder (not shown) or the like, and the upper and lower presses are stopped in a state where both single discs, the adhesive and the felt are completely pressed. This method is described in, for example,
No. 241216 and JP-A-10-255341. Conventionally, in the case of such a laminated disk, the clearance between the inner diameter of the substrate and the outer diameter of the pin for aligning the core in FIG. 14 was about 50 μm or more in consideration of variations in the substrate. In some cases, the weight balance, that is, the eccentricity was deteriorated. According to the study by the present inventors, it has been found that the upper and lower face plates are inclined and are not pressed in parallel during the pressing shown in FIG. 15, so that the adhesive spreads unevenly and the thickness of the disc becomes uneven. Further, in the step shown in FIG. 12, the amount of the adhesive oozing out of the mesh of the screen plate with the squeegee may be uneven, and this cannot be absorbed by the conventional pressing method. Adhesive thickness is 20
Although the thickness was adjusted to about 100 μm, the weight balance changed as the thickness increased. As the thickness is reduced, the eccentricity is easier to control, but in the conventional pressing method, the adhesive acts as a cushion that absorbs the bias of the pressing pressure, and the cushioning effect weakens, causing local stress. The runout acceleration was worse. In other words, the conventional laminating method cannot reduce the eccentricity due to the displacement of the positions of the two single discs and the uneven thickness of the adhesive. There was a limit to use it.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide an optical disk using a thin injection molded substrate that can withstand use of a handy movie having a small eccentricity, a bonded optical disk using a thin injection molded substrate, and a method and apparatus for manufacturing an optical disk.

[0017]

In order to achieve the above object, a bonded optical disk according to a first aspect of the present invention includes a single injection-molded substrate having a thickness of 0.8 mm or less, and has an outer diameter of 0.8 mm or less. It is characterized in that it is 100 mm or less and the eccentricity is 0.1 g · cm or less. Such an optical disk has a small eccentricity of 0.1 g · cm or less, and can perform normal recording and reproduction without applying an overload to the spindle even when applied to a handy type movie. Further, such an optical disc is small as 100 mm or less in diameter, so that it is suitable as a portable medium and can maintain a small eccentricity. Further, such an optical disk has a thin single plate thickness of 0.8 mm or less, so that it is light in weight and convenient for carrying. Further, since such an optical disk is a bonded type, even when the eccentricity of each single plate is 0.1 g · cm or less and the eccentricity of the entire optical disk is 0.1 g · cm, each of the two single plates is eccentric. Is 0.1 g · cm or more, but also includes a case where the eccentricity of the entire optical disc becomes 0.1 g · cm by combining the two so that the phases are canceled.

A bonded optical disk according to another aspect of the present invention includes a single injection-molded substrate having a thickness of 0.8 mm or less, and is capable of recording on both sides with an eccentricity of 0.05 g · cm or less. And Such an optical disc has a small eccentricity of 0.05 g · cm or less, and can perform normal recording and reproduction without overloading the spindle even when applied to a handy type movie. Further, such an optical disk has a thin single plate thickness of 0.8 mm or less, so that it is light in weight and convenient for carrying. Further, since such an optical disk can perform double-sided recording, it is more convenient than an optical disk that can perform only one-sided recording using a dummy plate.

An optical disc according to another aspect of the present invention comprises:
The eccentricity is 0.01 g · cm or less. Such an optical disk has a small eccentricity and can perform normal recording and reproduction without applying an overload to the spindle even when applied to a handy type movie. The outer diameter of the optical disk does not matter as long as the center of gravity falls within this range. Such an optical disk may be a bonded optical disk.

According to another aspect of the present invention, there is provided a method of manufacturing an optical disk, comprising: a fixed mold; and a cavity movably provided with respect to the fixed mold to define an optical disk substrate together with the fixed mold. A movable mold to be formed; a first parallel maintaining mechanism for maintaining parallelism when the movable mold moves; and a center hole of the substrate after the material for forming the substrate is filled in the cavity. And injection molding the substrate having a thickness of 0.8 mm or less using a mold having an eccentricity adjusting portion for adjusting the eccentricity of the punching portion movably provided on the substrate. Such a method is the first
Since the mold whose eccentricity is prevented by the parallel maintaining mechanism and the eccentricity adjusting portion is used, an optical disk having a small eccentricity as described above can be manufactured. In this case, the mold may further include a tilt mechanism for tilting the cavity at an arbitrary height. As a result, it is possible to prevent uneven stress from being applied to the cavity. Such a mold also constitutes another aspect of the present invention.

The two substrates are bonded together and have an outer diameter of 100 m.
The method may further include the step of forming an optical disk capable of recording data of m or less and / or capable of recording on both sides. As described above, it is desirable to prevent the eccentricity of these small or double-sided recordable optical disks.

In the forming step, the two substrates are attached to pins, and the clearance between the diameter of the center hole and the diameter of the pins is 50 μm / φ or less, more preferably 10 μm.
There may be a step of adjusting the value to / φ or less. By making the clearance small, an optical disk having a small eccentricity can be formed.

The forming step includes a fixed press, a movable press movably provided with respect to the fixed press and pressing the substrate together with the fixed press, and a second step for maintaining parallelism during movement of the movable press. Forming an optical disk by laminating the two substrates using a press having two parallel maintaining mechanisms. The second parallel maintainer prevents the generation of uneven stress on the substrate. Such a press also constitutes another aspect of the present invention.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the effects of the present invention will be described in detail with reference to examples.

[0025]

Embodiment 1 FIG. 1 is a sectional view of a main part of an optical disk mold according to the present embodiment. In one direction of the guide ring 33, a guide ring parallel maintaining function 5 including a guide pin 2, a guide bush 3 and a guide pin support member 1 is added. The guide ring parallel maintaining mechanism 5 is attached in the following procedure so as not to impair the alignment accuracy of the guide ring. First, both molds are temporarily fixed to a molding machine with bolts, and the molds are sufficiently heated in a state where the parting line 30 is not opened and alignment is not performed, that is, in a state where no mold clamping force is generated. Next, in a state where one of the fixed mold and the movable mold is tightened to the molding machine, a mold clamping force is generated, the guide ring 33 is closed, and the other mold is completely tightened. Attach. According to this method, first, the alignment accuracy of the guide ring is maintained in a state where the molding temperature is increased.
Further, the guide ring parallel maintaining mechanism 5 is temporarily fixed to the mold, and after the temperature is raised, a mold clamping force is generated to completely fix the guide pin 2 and the guide bush 3. With this mounting method, the guide ring parallel maintaining mechanism 5 does not work when the parting line 30 is closed at the time of guide ring alignment, but works only when the parting line opens and the alignment of the guide ring is impaired.

By mounting the guide ring parallel maintaining mechanism 5, the cavity is formed even in the guide ring mold as shown in FIG.
The parallelism is not significantly impaired even when it is opened as described above, and the thickness unevenness of the substrate can be reduced.

The mold of the present invention has a ring-shaped eccentricity adjusting ring 4 which can shift the position of a spool bush 15, which is a female cutter on the fixed mold side into which the cut punch 12 is inserted, in an arbitrary direction. are doing. When the cut punch, which is a male cutter, is eccentric to the female cutter,
Since the cut punch is inserted obliquely in accordance with it, the eccentricity of the outer diameter with respect to the inner diameter becomes large and the eccentricity becomes large. Therefore, the eccentricity adjusting ring 4 is eccentric beforehand so that the spool bush is not inclined. 15 can be adjusted as shown in FIG. In this embodiment, first, an eccentricity adjusting ring which is not eccentric was attached, and then the substrate was formed. The molded substrate was measured with a tool microscope. This molded substrate has an outer diameter of 20 μm (0
-P) The spool bushing 15 is moved in the direction of correcting the eccentricity of the eccentricity adjusting ring 4 which has been eccentrically eccentric by 20 μm.
Attached to the outside. As a result, the eccentricity of the outer diameter with respect to the inner diameter of the molded substrate was reduced to 3 μm (0-P).

Next, using the mold of this embodiment, the plate thickness is 0.6 mm.
A molded substrate for DVD-RAM having an inner diameter of 15 mm and an outer diameter of 80 mm was manufactured. The molding machine is a molding machine SD30 with a direct pressure type clamping mechanism manufactured by Sumitomo Heavy Industries, and the stamper is DVD
-RAM format (recording capacity 1.46 GB per side, track pitch 0.615 μm), and polycarbonate resin AD5503 manufactured by Teijin Chemicals Limited was used. The set temperature of the mold temperature control is 122 for both the fixed mold and the movable mold.
° C, the resin (cylinder) temperature was 380 ° C, the maximum filling speed was 300 mm / s, which is the maximum capacity of the molding machine, and the filling time was 0.08 s. Maximum cavity opening is 300μ
m. When the maximum value of the formed substrate in one round thickness unevenness was measured by an Anritsu laser thickness measuring device, it was 4 μm at an outer radius of 38 mm. The thickness unevenness over the entire signal area was 6 μm. The eccentricity of this substrate was measured by a Shimadzu dynamic balance tester DBM-VC type measuring apparatus, and it was 0.02 g · cm.

After forming a phase change recording film on the recording surface of the molded substrate by sputtering, a hard coat film of an ultraviolet curable resin is formed on the incident surface side to a thickness of 2 μm, and a protective film of the ultraviolet curable resin is formed on the sputtered recording film. A 10 μm film was formed to produce a single-plate disk. Next, the recording surfaces of the single-plate disks were opposed to each other, and were bonded by a screen printing method. In the present invention, two improvements were made in the bonding process.

First, when the substrates shown in FIG. 14 are overlaid, the clearance between the inner diameter of the substrate and the outer diameter of the pin should be one.
0 ± 5 μm / Φ. The inner diameter of the substrate was measured, and a pin having the most appropriate outer diameter was attached. The outer diameter of the positioning pin was prepared from Φ15,000 mm to Φ15.100 mm in increments of 0.01 mm / Φ. In this embodiment, since the inner diameter of the substrate was in the range of Φ15.060 to 15.065 mm, a pin having an outer diameter of Φ15.050 was used.

Second, the press face plate at the time of bonding is changed as shown in FIGS. The positioning in the height direction at the time of completion of the pressing was performed not by the single-plate disks as in the conventional case but by a ring-shaped receiving plate provided on the outer periphery of the pressing face plate. In addition, since the ring-shaped receiving plate 17 on one side is uniformly floated in the height direction by the spring 16, even if the upper face plate is tilted, the upper and lower face plates are closed in parallel, so that the single-plate disc is uneven. No stress is generated.

In addition, the felt, which is an elastic body conventionally attached on the press, is detached so that the parallelism between the presses can be maintained. When the thickness of the adhesive was 50 μm, the thickness of the laminated disc was 1.29 mm in calculation. When the press is completed, the distance T between the upper and lower presses is equal to the disc thickness-
The distance was set to 1.28 mm with 0.01 mm as a standard. With this method, even if the adhesive has uneven coating, the height is determined by the face plate, so that the nonuniformity of the disk thickness is suppressed.

The eccentricity of the DVD-RAM disc having an outer diameter of Φ80 mm bonded in this embodiment was 0.03 g · cm. Tilt was good, being within 0.2 °. The thickness unevenness of the disk was 8 μm.

A DVD with an outer diameter of Φ80 mm in the present embodiment
-When the RAM disk was recorded as a movie, it could be recorded and reproduced without any problem even if it was moved greatly while shooting.

[0035]

[Embodiment 2] The same mold as that of Embodiment 1 was used to obtain a plate thickness of 0.6.
A molded substrate for DVD-RAM having an inner diameter of 15 mm and an outer diameter of 80 mm was prepared. The molding machine is a molding machine SD30 with a direct pressure type clamping mechanism manufactured by Sumitomo Heavy Industries, and the stamper is D
VD-RAM format (1.46G single-sided recording capacity)
B, track pitch of 0.615 μm), and AD5503 manufactured by Teijin Chemicals Ltd. was used as the polycarbonate resin. The temperature setting of the mold temperature control is 122 ° C. for both the fixed mold and the movable mold, the resin (cylinder) temperature is 380 ° C., the maximum filling speed is 300 mm / s, which is the maximum capacity of the molding machine, and the filling time is 0.08 s. And The maximum opening amount of the cavity was 300 μm. The maximum value of the formed substrate in one round thickness unevenness was measured by an Anritsu laser thickness measuring machine. Since the measuring device is a non-contact type, it can accurately measure an infinite point in one circumference. When n = 10 sheets were measured, outer radius r = 38 m
m was 3 to 5 μm. The thickness unevenness over the entire signal area was 4 to 6 μm. The average of the absolute values of the plate thickness over the entire surface was 0.600 mm.

After a phase change recording film is formed on the recording surface of the molded substrate by sputtering, a hard coat film of an ultraviolet curable resin is formed on the incident surface side at 2 μm, and a protective film of the ultraviolet curable resin is formed on the sputtered recording film. A 10 μm film was formed to produce a single-plate disk. It was confirmed that the thickness unevenness in one circumference of the protective film was all within 2 μm. Next, the recording surfaces of the single-plate disks were opposed to each other, and were bonded by a screen printing method. In this embodiment, a screen printing type DVD bonding apparatus manufactured by Pioneer Video Co., Ltd. was used as the bonding apparatus, and SK7000 manufactured by Sony Chemical was used as the adhesive. The average thickness of the adhesive on one side of the substrate before bonding is 40 μm
The roughness of the mesh of the screen plate and the pressure of the squeegee were adjusted so as to be as follows. The outer diameter of the mesh plate that determines the area to which the adhesive is applied is φ0.
The diameter of the screen plate was adjusted by 5 mm to φ79.5 mm, and the position of the screen plate was adjusted in front, rear, left, and right so that the center B of the outer diameter after applying the adhesive to the center A of the outer diameter of the molded substrate did not shift. In this example, the adjustment was performed while curing the adhesive of the substrate before bonding and measuring with a tool microscope such that the deviation between A and B was within 10 μm. Further, also in the present embodiment, the above two improvements were made in the bonding step.

In addition, the felt, which is an elastic body conventionally attached on the press, is detached so that the parallelism between the presses can be maintained. The total thickness of the bonded disc before pressing was calculated to be 1.304 mm. The distance T between the upper and lower presses at the completion of the press was set to 1.294 mm with the disc thickness of -0.01 mm as a guide. With this method, even if the adhesive has uneven coating, the height is determined by the face plate, so that the nonuniformity of the disk thickness is suppressed.

The eccentricity of the DVD-RAM disc having an outer diameter of Φ80 mm bonded in this embodiment was measured by using a Shimadzu dynamic balance tester DBM-VC type measuring apparatus. In this embodiment, the value of the eccentricity of each disk is defined as an average value measured three times while changing the mounting direction to the apparatus in the circumferential direction. The maximum and minimum values of the eccentricity of the five bonded optical disks were 0.01 g · cm and 0.005 g · cm, respectively.
Outer circumference r = 38 mm of the total thickness of these two optical disks
Of contact thickness measurement (Kuroda Seiko DT
M-120) is shown in Table 1, and the results are from 8 to 10
μm. The maximum value of R-Tilt was within 0.2 °, which was good.

A problem during recording of the optical disk of this embodiment in movie applications was verified by the following method. That is, a DVD-CAM (DZ-MV100) manufactured by Hitachi, Ltd. was used as a movie as a recording device, and the optical disc was inserted into a vibration tester (G-0050 manufactured by Shinken), and the movie was fixed at a vibration frequency of 35 Hz. Vibration was performed while recording under the condition of an amplitude of 0.15 mm. The vibration test time, that is, the recording time, was changed to 10 s, 20 s, and 30 s, respectively. After the vibration test, the movie was stopped and the recorded screen was played back, and the time during which the screen flickered was measured. The same optical disk was tested three times under the same conditions, and the average time was taken as the flickering time of the recording screen under each condition. Table 1 shows the test results in this example. As shown in Table 1, no problem was observed during reproduction of the recorded screen under all vibration conditions for both optical discs in this embodiment. In addition, as a result of actual handling and a video recording test, it was confirmed that the video recording was normally performed and no problem was caused even if the camera shake was intentionally increased.

[0040]

Example 3 Molding was carried out in the same manner as in Example 1 except that the mold was adjusted by sandwiching a shim so that the mold cavity was inclined at an arbitrary height in the circumferential direction. Then, a single-plate substrate having an uneven thickness of the substrate of 10 μm was prepared, and a bonded disc was prepared in the same manner as in Example 1. The thickness unevenness of the disk was 15 μm. At this time, the eccentricity was 0.05 gcm. Further, when a DVD-RAM disk having an outer diameter of Φ80 mm in this embodiment was recorded as a movie, it could be recorded and reproduced without any problem even if it was largely moved while shooting.

[0041]

Example 4 An optical disk was manufactured in the same manner as in Example 2 except that the pressing in the bonding step was performed by a conventional method of bringing substrates into contact with each other. The eccentricity of the optical disc after bonding in this embodiment is from 0.025 cm to 0.05.
g · cm. Table 1 shows the measurement results of the total thickness unevenness of the optical disc and the results of measuring the image flickering time in the vibration test as in Example 2. As shown in Table 1, the thickness unevenness of the optical disk according to the present embodiment is 40 μm or more, which is worse than that of the first embodiment.
The flickering was observed during playback of the recorded screen for each of the images. However, when the camera shake was intentionally increased, it was confirmed that 90% or more of the recording was performed normally.

[0042]

Fifth Embodiment An optical disk is manufactured in the same manner as in the fourth embodiment except that a conventional positioning pin in which the outer diameter of the positioning pin and the inner diameter of the substrate at the time of pressing in the bonding step are approximately 50 μm / φ is used. did. In this embodiment, the eccentricity of the bonded optical disk is from 0.07 g · cm to 0.
It was 10 g · cm. Table 1 shows the measurement results of the total thickness unevenness of the optical disc and the results of measuring the image flickering time in the vibration test as in Example 2. As shown in Table 1, the flicker of 2 s or less was observed on the recording screen of all the two optical disks in this embodiment under all vibration conditions. It was confirmed that similar symptoms occurred at a frequency of 40% when the camera shake was intentionally increased. (Comparative Example 1) The guide pin 2 and the guide bush 3 which are the guide ring parallel maintaining mechanism 5 at the time of manufacturing a molded substrate.
An optical disk was manufactured in the same manner as in Example 5, except that the mold was removed from the mold and molded. As shown in Table 1, the thickness unevenness and the eccentricity of the single-plate substrate were worse than those of the optical disk of the present embodiment. The eccentricity of the bonded optical disc in this comparative example is from 0.14 g · cm to 0.2.
It was 0 g · cm. Table 1 shows the measurement results of the total thickness unevenness of the optical disc and the results of measuring the image flickering time in the vibration test as in Example 2. As shown in Table 1, both optical discs in this comparative example showed flickering on the recording screen under all vibration conditions. Furthermore, it was confirmed that the same symptom occurs in 80% or more cases even when the camera shake is intentionally increased. (Comparative Example 2) A substrate was molded in the same manner as in Example 1 except that the guide ring parallel maintaining mechanism 5 was removed from the molding die to complete a bonded disc. The thickness unevenness of the single-plate molded substrate was 17 μm, and the thickness unevenness of the finished disk was 23 μm. The eccentricity is 0.12 g · cm, and when a DVD-RAM disk with an outer diameter of Φ80 mm in this comparative example was recorded as a movie, if it was moved greatly while taking a picture, it could not be recorded normally, resulting in dropped frames and blurred screens. Problem occurred. (Comparative Example 3) Eccentricity adjusting ring 4 when manufacturing a molded substrate
The optical disk was manufactured in the same manner as in Comparative Example 2 except that the mold was removed from the mold and returned to the original ring without eccentricity. Table 1 shows the thickness unevenness and the amount of eccentricity of the single-plate substrate. The amount of eccentricity was worse than that of the optical disk of Comparative Example 2. The eccentricity of the bonded optical disc in this comparative example was from 0.35 g · cm to 0.46 g · cm. Table 1 shows the measurement results of the total thickness unevenness of the optical disc and the results of measuring the image flickering time in the vibration test as in Example 2.

As shown in Table 1, both of the optical disks in this comparative example showed flickering on the recording screen for a long time under all vibration conditions. Furthermore, it was confirmed that a similar symptom occurs in all cases when the camera shake is intentionally increased.

FIG. 16 is a graph showing the relationship between the eccentricity of each optical disk shown in Table 1 and the flickering time of the recorded image. FIG.
As shown in FIG. 6, the flickering time of the recorded image is 0.
It is clear that the length is remarkably longer if it is larger than 1 g · cm. Also, in the video recording test handled as described above, when the eccentricity is larger than 0.1 g · cm, serious harm was found. Therefore, if the eccentricity is not less than 0.1 g · cm as in the optical disk of this embodiment, it is considered that a serious problem will occur in an optical disk for movie use.
Further, as shown in Table 1, the eccentricity was set at 0.
It is more preferable that the eccentricity is not more than 05 g · cm, and it is most preferable that the eccentricity be not more than 0.01 g · cm as in the second embodiment.

[0045]

[Table 1]

The form of the optical disk of the present invention was a bonded disk using a thin substrate having an eccentricity of 0.1 g · cm or less. In order to achieve this, a mechanism for reducing thickness unevenness and eccentricity of the injection molded substrate is provided by devising a mechanism for maintaining parallelism in a molding die. Also, the eccentricity of the bonded disk is prevented from increasing by a method of suppressing the displacement of the disk at the time of bonding.
These optical disks are suitable for use in movies and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional structural view of a main part of an optical disk mold used in the present invention.

FIG. 2 is a cross-sectional structural view of a main part of an optical disk mold used in the present invention, schematically showing a behavior at the time of injection filling.

FIG. 3 is a cross-sectional structural view of a main part of an optical disk mold used in the present invention, and schematically shows a behavior when a cut punch is inserted.

FIG. 4 is a cross-sectional view of a laminated face plate used in the present invention.

FIG. 5 is a cross-sectional view schematically showing a state in which the substrate is pressed by the bonding face plate used in the present invention.

FIG. 6 is a diagram showing a configuration of a bonded optical disk.

FIG. 7 is a cross-sectional view of a main part of a conventional optical disk mold.

FIG. 8 is a cross-sectional structural view of a main part of a conventional optical disk mold, schematically showing a behavior at the time of injection filling.

FIG. 9 is a cross-sectional structural view of a main part of a conventional optical disk mold, schematically illustrating a behavior when a cut punch is inserted.

FIG. 10 is a view showing a conventional process of curing a protective film with ultraviolet rays.

FIG. 11 is a view showing a step of applying a bonding adhesive in a conventional screen printing method.

FIG. 12 is a view showing a bonding adhesive having a predetermined thickness formed by a conventional screen printing method.

FIG. 13 is a view showing a step of starting a reaction of a bonding adhesive in disk bonding using a conventional screen printing method.

FIG. 14 is a view showing a centering process at the time of laminating in a disk lamination using a conventional screen printing method.

FIG. 15 is a view showing a pressing step in a disk bonding using a conventional screen printing method.

FIG. 16 is a graph showing the relationship between the eccentricity of the optical disc of the present invention and image flicker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Guide pin support member 2 Guide pin 3 Guide bush 4 Eccentricity adjustment ring 5 Guide ring parallel maintenance mechanism 6 Pin outside diameter 7 Board inside diameter 8 Injection molding board 11 Stamper 12 Cut punch 16 Spring 17 Face plate outer ring 29 Adhesive 30 Parting Line 31 Cavity 33 Guide ring

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Claims (13)

[Claims] 1. Includes a single-piece injection molded substrate having a thickness of 0.8 mm or less, an outer diameter of 100 mm or less, and an eccentricity of 0.1 g ·
cm. 2. A bonded optical disk including a single injection molded substrate having a thickness of 0.8 mm or less and capable of recording on both sides with an eccentricity of 0.05 g · cm or less. 3. An optical disc having an eccentricity of 0.01 g · cm or less. 4. The optical disk according to claim 3, wherein said optical disk is a bonded optical disk. 5. A fixed mold, a movable mold movably provided with respect to the fixed mold to form a cavity defining an optical disc substrate together with the fixed mold, and a movable mold when the movable mold moves. A first parallel maintaining mechanism for maintaining the parallelism of the substrate, and adjusting the eccentricity of a punched portion movably provided so as to punch a center hole of the substrate after the material for molding the substrate is filled in the cavity. A method for manufacturing an optical disk, comprising: using a mold having an eccentricity adjusting part, and injection-molding the substrate having a thickness of 0.8 mm or less. 6. The method for manufacturing an optical disk according to claim 5, wherein the mold further includes a tilt mechanism for tilting the cavity at an arbitrary height. 7. The method according to claim 7, wherein the two substrates are bonded together and have an outer diameter of 100.
6. The method for manufacturing an optical disk according to claim 5, further comprising a step of forming an optical disk having a diameter of not more than mm. 8. The method for manufacturing an optical disk according to claim 5, further comprising a step of forming an optical disk capable of recording on both sides by bonding two substrates. 9. The method according to claim 7, wherein the forming step includes attaching the two substrates to pins and adjusting a clearance between a diameter of the center hole and a diameter of the pins to 50 μm / φ or less. Manufacturing method of optical disk. 10. The method according to claim 7, wherein the forming step includes a step of attaching the two substrates to pins and adjusting a clearance between a diameter of the center hole and a diameter of the pins to 10 μm / φ or less. Manufacturing method of optical disk. 11. The forming step includes: a fixed press;
A press having a movable press movably provided with respect to the fixed press and pressing the substrate together with the fixed press, and a second parallel maintaining mechanism for maintaining parallelism during movement of the movable press is used. Forming an optical disk by bonding the two substrates together. 12. A fixed mold, a movable mold movably provided with respect to the fixed mold to form a cavity defining an optical disk substrate together with the fixed mold, and a movable mold when the movable mold moves. A parallel maintaining mechanism for maintaining the parallelism of the substrate, and an eccentric adjustment for adjusting the eccentricity of a punched portion movably provided so as to punch a center hole of the substrate after the material for molding the substrate is filled in the cavity. And a mold having a part. 13. A fixed press, a movable press movably provided with respect to the fixed press and pressing the substrate together with the fixed press, and a parallel maintaining mechanism for maintaining parallelism when the movable press moves. With a press.