JP2003059123A - Method of manufacturing optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process step in which the thickness of a resin layer to be formed by a spin coating method is formed in nearly a uniform thickness, which simplified and suppressed in unnecessary waste by devising a method of forming a central hole of a disk-like substrate material. SOLUTION: The method of manufacturing optical disk comprises injecting a synthetic resin from a gate 33 into a cavity of a mold assembly 30 to form the disk-like substrate material 12, solidifying and molding a central part 26 together with a sprue runner 14 in the gate 33, returning the once blanked sprue runner 14 and the central part 26 to the disk-like substrate material 12 so as to be integrated with the disk-like substrate material 12 and forming a recording layer, etc., on the disk-like substrate material 12 formed in the manner described above and further forming a resin layer thereon, then blanking the central part 26 together with the sprue runner 14 to form a central hole 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc manufacturing method.

[0002]

2. Description of the Related Art Generally, CD (Compact Disc) and D
For a disc-shaped optical recording medium (optical disc) such as a VD (Digital Versatile Disc), a stamper formed by a mastering process is mounted in a mold installed in an injection molding machine, and an area serving as an information recording surface is injection-molded. By forming a disc-shaped substrate material made of resin, a recording layer or the like that can be recorded or a reflective layer that is provided to make it reproducible is formed on this, and a protective layer made of resin is provided on it. Are manufactured.

More recently, for example, Japanese Patent Laid-Open No. 8-2356.
As disclosed in Japanese Patent Laid-Open No. 38-38, a support layer (protective layer) that does not need to transmit light, that is, does not require an optical thickness, is formed as a disc-shaped substrate material (substrate) to be thick by injection molding. After a reflective film provided for reproducing on the information recording surface side of the substrate, or a recording layer configured for recording is formed, light by a transparent resin layer capable of transmitting a recording / reproducing laser beam is formed thereon. Attention has also been paid to an optical disk manufactured by a manufacturing method in which a transparent layer (a resin layer corresponding to a protective layer in the above-mentioned CD or the like) is laminated.

Conventionally, in the manufacture of optical discs, a circular hole is formed in the center of a substrate by removing the sprue runner solidified in the gate during injection molding during the substrate injection molding. After forming the disk-shaped substrate material by further forming the reflective film and the recording layer configured to be recordable, in the next step, for example, by a spin coating method, a resin protective layer or a light-transmitting resin is formed. The finished product is formed by forming a light-transmitting layer consisting of.

As one of the characteristic manufacturing methods of the protective layer or the light transmitting layer of these optical disks, as disclosed in Japanese Patent Application Laid-Open No. 10-249264, a lid-like member for covering the center hole of the optical disk. There is a manufacturing method in which a protective layer (resin layer) is formed by spin coating a resin on it, spreading it over the entire surface of the optical disc, and curing the resin.
Since this method can be easily controlled in the coating surface so that the layer thickness of the resin layer becomes substantially uniform in the radial direction in particular, it is also applied to Japanese Patent Laid-Open No. 1996-235638 in which a light transmitting layer is formed. Has been done.

[0006]

When the above-mentioned spin coating method for the resin layer is applied, a lid-like member is required in the center hole of the disc-shaped substrate material.

In this manufacturing method, it is desired that the lid-shaped member is clean, and if one lid-shaped member is always used, a step such as washing after once using it for resin coating is required. Moreover, a new (clean) one must always be used by disposing of the lid-like member.

Further, as described above, when the central hole is closed by the lid-like member during spin coating, the light-transmitting resin usually flows down from the lid-like member position to the disc-shaped substrate material, so that the lid-like shape is obtained. There is a problem that bubbles inside the resin layer due to the step between the member and the surface of the disk-shaped substrate material and uneven streaks on the surface of the resin layer are likely to occur, and the layer thickness (film thickness) becomes uneven. .

On the other hand, as described in, for example, Japanese Patent Application Laid-Open Nos. 5-92492 and 5-185477, for the purpose of minimizing the effects of burrs and resin waste due to punching of the center hole, A method of manufacturing an optical disc has been proposed in which a center hole is opened in a post process.

An attempt was made to apply such a method as a substitute for the lid-like member used in the formation of the resin layer, but if the punching portion is made thinner in advance in order to make it easier to open the center hole in a later step, This leads to problems such as difficulty in filling the resin during molding and distortion in the molded disc-shaped substrate material.If a certain amount of thickness is provided, then the optical disc will be distorted during punching. It will cause problems such as being damaged and making punching difficult.

Further, when the central hole is formed in a later step,
In many cases, the light-transmissive resin protrudes unevenly on the outer periphery of the disk-shaped substrate material, and it is difficult to accurately position the central portion to form the central hole. There is a problem that eccentricity is likely to occur between the material and the material.

The present invention has been made in view of the above problems of the prior art. By optimally forming the state near the center hole during injection molding, the film thickness of the resin layer to be formed later can be easily reduced. In addition, it is possible to control uniformly, further simplifying the process as in the case of using the lid-shaped member, in addition, compared with the conventional manufacturing method using the lid-shaped member, It is an object of the present invention to provide a method for manufacturing an optical disc, which improves the yield and can form a necessary center hole accurately without causing eccentricity or the like.

[0013]

As a result of earnest research, the inventor of the present invention has taken out a disk-shaped substrate material integrally with a sprue runner at the time of injection molding, and as it is, a film forming step and a resin layer forming step. Thus, the above-mentioned problems are solved by forming an optical disc through the process.

That is, the following problems can be solved by the following inventions.

(1) A disk-shaped injection-molded substrate material made of synthetic resin is formed into a center hole to form a center hole. A method for manufacturing an optical disc, characterized in that the central hole is closed by being slightly inserted into and fitted into the optical disc, and is integrated with the substrate material.

(2) The mold for producing the disk-shaped substrate material is composed of a fixed mold and a movable mold, and the movable mold is provided with a center hole molding insert which can move forward and backward with respect to the fixed mold. After the injection of the synthetic resin from the gate of the mold into the cavity, the center hole molding insert is moved in the fixed mold direction to move the center portion of the disk-shaped substrate material under pressure in the cavity. A pulling step of pulling out together with a sprue runner in the gate to form a central hole, and then pushing back the central portion slightly to the central hole to close the central hole and pushing back together with the disc-shaped substrate material. The method for producing an optical disk according to (1), characterized in that the disk-shaped substrate is held and taken out from the mold apparatus through the steps.

(3) On the disk-shaped substrate material integrated with the sprue runner in the gate at the time of injection molding, the step of forming the recording layer at the time of the injection molding and the light transmitting resin layer after the injection molding. (1) or (2), which comprises at least one of the steps.

(4) After completion of at least one of the step of forming the recording layer and the step of forming the light-transmitting resin layer, the sprue runner together with the central portion of the disk-shaped substrate material is used. Characterized by having a step of removing from the material to form a central hole (3)
Optical disc manufacturing method.

(5) In the pushing back step, the thickness of the central portion is made by utilizing a returning step of slightly returning the center hole forming insert into the center hole and a pressure difference in the cavity generated by the returning step. Pressing part of the direction into the central hole,
(2) A method of manufacturing an optical disk, which comprises a closing step of closing the central hole.

(6) The moving position of the insert for molding the central hole in the direction of the fixed mold is at least a penetrating position in which the tip projects from the central hole in the removing step and the tip is slightly inside the central hole. It is set to multiple stages of the retracted position that returned,
The discharging step is started after the resin is filled into the mold device and before the pressure holding step before cooling, and is ended immediately before the pressure holding step is finished, and at the same time, the returning step to the retracted position is started. , (2) or (5), which is continued until the mold is opened.
Optical disc manufacturing method.

(7) The method of manufacturing an optical disc according to (6), wherein the step of removing is started by using a delay timer after a predetermined time has elapsed from the start of the injection or the end of the injection.

(8) The end timing of the withdrawal step and the start timing of the returning step are set to be the injection start or a set time after the injection end by using a forward end timer (6). ) Or (7) The method for manufacturing an optical disc.

(9) The pressure-holding step is finished by a pressure-holding timer after a preset time has passed from the start of closing the mold (6), (7) or (8). Optical disc manufacturing method.

(10) The removing step is characterized in that the central portion is punched by an ultrasonic press (4).
Optical disc manufacturing method.

(11) In the method of manufacturing an optical disk according to (4) or (5), the sprue runner is used as a positioning reference for the disk-shaped substrate material in the step of removing the central portion.

(12) In at least a part of the process until the substrate material taken out from the mold device is completed as a disk substrate, on the surface opposite to the information area on the information recording surface of the substrate material. The method for manufacturing an optical disk according to (4), (10) or (11), characterized in that the area is brought into contact with and transported.

(13) A method of manufacturing an optical disk according to (12), characterized in that an area on the opposite surface corresponding to the information area on the information recording surface of the substrate material is adsorbed and conveyed by negative pressure. .

(14) A disk-shaped injection-molded substrate material made of a synthetic resin, and a central portion formed by cutting out the center of the substrate material. A disk characterized in that the center hole of the substrate material after being pulled out is slightly inserted in the thickness direction and fitted to close the center hole, and is integrated with the substrate material. Substrate intermediate.

(15) The disk substrate intermediate body, wherein the central portion is integral with the sprue runner which remains in the resin injection port and is solidified during the injection molding.

(16) A disk substrate intermediate which has at least one of a film and a light-transmitting resin layer formed on one surface of a substrate material which is integral with the central portion.

(17) A disk substrate intermediate before being processed into a disk-shaped disk substrate having an information recording area on one surface, wherein the information recording area on the surface opposite to the one surface is formed. A disc substrate intermediate, which has irregularities of 0 to 100 μm in a corresponding region.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

With reference to FIG. 1, a method of manufacturing an optical disk according to the first example of the embodiment of the present invention will be described.

In this manufacturing method, first, a stamper 10 (FIG. 1) on which a pattern for forming an information recording surface is mastered.
(See (A)) is set in a mold device 30 (see FIG. 2), and a synthetic resin is injected into the cavity of the mold device 30 to mold the disk-shaped substrate material 12.

In the injection molding process, the central portion 26 of the disk-shaped substrate material 12 is once removed together with the sprue runner 14 to form a central hole 28, and the removed central portion 26 is slightly returned to the central hole 28. This is closed and integrated with the disk-shaped substrate material 12, then a sputtering process, a spin coating process, a hard coating process, etc. are performed, and then the central portion 26 is deleted together with the spool runner 14. It is a thing.

In the example of this embodiment, as shown in FIG. 2, the mold device 30 is provided with a center hole molding insert 35 on the movable mold 34 side, which protrudes toward the fixed mold 32 side. In addition, the stamper 10 has a through hole 10A formed at the center thereof through which the center hole forming insert 35 penetrates, and in the mold device 30, a movable mold 34 is formed.
Is located on the side opposite to the gate 33 for injecting the synthetic resin.

Next, a process in which the center hole 28 is once formed in the disk-shaped substrate material 12 by the mold device 30 and is closed by the center portion 26 will be described.

In the manufacturing method of this embodiment, after the synthetic resin is injected into the cavity of the mold, the center hole molding insert 35 is moved in the direction of the fixed mold 32 to maintain the pressure in the cavity. The disk-shaped substrate material 1 in
A second step of removing the central portion 26 together with the sprue runner 14 to form the central hole 28; and then, pushing the central portion 26 back slightly into the central hole 28 to close the central hole 28, The disc-shaped substrate material 12 is taken out from the mold device 30 through a push-back process in which it is integrated with the disc-shaped substrate material 12.

Here, in the pushing back step, a step of slightly returning the center hole forming nest 35 to the inside of the center hole 28, and a resin pressure difference in the cavity caused by this, the thickness direction of the center portion 13 is increased. A part of the central hole 28 is returned to the central hole 28 to close the central hole 28.

Regarding the above-mentioned pulling process and returning process,
This will be described in more detail with reference to FIGS. 3 and 4.

In the resin injection step, when the resin is filled in the cavity and the pressure is maintained, the state is as shown in FIG. 3 (A). Up to this point, as shown in FIG. 4, for example, the mold closing time is 0.2 to 0.5 seconds, the resin filling is 0.1 to 0.6 seconds, and the holding pressure is 0.1 to 3 seconds. It costs.

On the other hand, by the delay timer, the center hole molding insert 45 starts to move forward (raise in FIG. 3) 0 to 1.0 seconds after the start of injection or the end of injection, and at this time, as shown in FIG. ), The central portion 26 of the disk-shaped substrate material 12 is extruded (pulled out) upward in the drawing from the central hole 28 formed by the central hole forming nest 35.

The thickness of the central portion 26 is thinner than that in FIG. 3A because the resin, which is still in a fluidized state, escapes to the side when the center hole molding insert 35 rises.

The removing step by the center hole forming insert 35 is generally performed during the pressure holding step. Around the end of the holding pressure, as shown in FIG. 4, a cooling process of 10 seconds is performed.

On the other hand, the center hole molding insert 35 is immediately returned to the returning step for 10 seconds as shown in FIG. 4 after the removal step.

The front end of the center hole forming insert 35 is the center hole 2.
Returning to 8, the central portion 26 is pushed back into the central hole 28 together with the sprue runner 14 due to the pressure difference in the mold device 30.

When cooling is completed, the mold is opened, and the disk-shaped substrate material 12 is held and taken out, the central hole 28 is closed by the central portion 26, and the central portion 26 and the sprue runner 14 are disc-shaped. It is integrated with the substrate material 12.

In this state, as will be described later, if the central portion 26 is pushed out from the central hole 28 after the film formation, the formation of the light transmissive resin layer 22, etc., it can be easily removed.

Moreover, when the central portion 26 is removed once from the disk-shaped substrate material 12 and returned to the inside of the central hole 28,
Since the inner peripheral corner portion of the center hole 28 is squeezed by the center portion 26, a smooth edge is formed.

In the example of the above-mentioned embodiment, the center hole forming insert 35 returns slightly after the drawing process, but this is done by leaving the center hole forming insert 35 as it is.
The movable mold 34 may be slightly driven in the direction of the fixed mold 32 so that the tip of the center hole molding insert 35 relatively returns to the center hole 28.

Further, the time of the pressure-holding step shown in FIG.
The operation time of the delay timer, the time of the forward movement process of the center hole forming insert 35, the distance, and the distance of the backward movement process are not limited to these values, but the central portion 2 can be controlled by controlling these.
6, adhesion to the central hole 28, releasability, central hole 28
The burr in the vicinity can be controlled.

The disk-shaped substrate material of the present invention is suitable when it further has the following steps.

That is, as shown in FIG. 1 (B), the disk-shaped substrate material 12 manufactured by the above method is
The sprue runner 14 remaining in the gate 33 is integrally formed at the center position of the disk, but as it is, after that, a recording layer that is recordable by a sputtering method or a spin coat method, or a read-only recording layer is formed. To form a reflective layer, etc., and spin coating the resin on it to spread it over the entire optical disc and cure it,
Alternatively, a light transmitting layer (resin layer) is formed.

With respect to the disc-shaped substrate material 12 formed by integrally forming the sprue runner 14 (protruding portion) remaining in the gate 33 so as to project at the disc center position, the information recording layer is formed on the projecting side. It can be formed on either side or the other side, and it may be formed on either side. This is determined depending on whether the stamper 10 is attached to the movable side fixed side of the die, that is, in the present invention, particularly to the side with the punching pin or the side not having the punching pin.

Although FIGS. 1 and 3 show the case where the information layer (information recording surface 12A) transferred by the stamper 10 is provided on the side other than the protruding side, the subsequent steps will be described in this case. .

On the disk-shaped substrate material 12, a recording layer composed of a dye layer or the like is formed by a spin coating method, or a recording layer configured so that magneto-optical recording or phase change recording can be performed by a sputtering method. To form.
Here, layers such as a dielectric layer are formed before and after the recording layer by a sputtering method for various purposes. Further, thereafter, a reflective layer made of metal or the like is formed. On the other hand, when configuring a read-only optical disc, only the unit reflection layer is formed.

In the case of the spin coating method, an escape portion for accommodating the protruding portion may be formed in the central portion of the portion where the disk-shaped substrate material 12 is placed. The same applies to the case of the sputtering method. In the sputtering method, as shown in FIG. 1C, an inner and outer peripheral mask is used to cover a portion that does not require film formation, but the outer periphery is masked by an outer peripheral mask 13 as usual. May not be used, or an inner peripheral mask (not shown) may be attached near the center of the disk-shaped sputtering target.

Next, as shown in FIG. 1D, the resin material (light transmissive resin) is applied to the nozzle 20 while rotating the disc-shaped substrate material 12 in the horizontal plane with the sprue runner 14 facing downward. Then, a resin layer (light-transmitting resin layer) 22 (in FIG. 1D, the resin layer 22 extends halfway in the radial direction of the disk-shaped substrate material 12) is formed on the film 18 by spin coating.

Also at this time, an escape portion for accommodating the sprue runner 14 is formed in the central portion of the portion where the disc-shaped substrate material is installed. Since there is no center hole of the optical disc near the center of the disc-shaped substrate material 12, it is possible to use a lid-like member for covering the center hole of the optical disc as disclosed in JP-A-1998-249264. A protective layer (resin layer) can be formed by spin-coating the resin and spreading it over the entire optical disk and curing it. The coating surface should be such that the layer thickness of the resin layer is almost uniform, especially in the radial direction. It will be easier to control within.

Further, a hard coat protective layer may be formed on the resin layer 22 in the same manner.

Next, as shown in FIG. 1 (E), the sprue runner 14 is pressed from the opposite side of the information recording surface 12A by a punch 25 in an ultrasonic pressing device, for example.
At the same time, the central portion 26 of the disk-shaped substrate material 12 is punched to form a central hole 28.

At this time, the positioning of the disk-shaped substrate material 12 at the time of ultrasonic pressing may be performed with reference to the pattern of the information recording surface 12A.

When the gate 33 is set to be located at the center of the disk-shaped substrate material 12, the sprue runner 14 may be used as a reference.

In FIG. 1, the injection-molded disc-shaped substrate material 12 is conveyed by grasping the surface on which the sprue runner 14 is formed, that is, the surface opposite to the information recording surface 12A. For example, the disk-shaped substrate material 12 is formed by the vacuum suction device 36 as shown in FIGS.
The side opposite to the information recording surface 12A may be sucked and conveyed, or the outer peripheral portion may be mechanically chucked (hooked by a claw). Alternatively, the sprue runner 14 may be grasped and conveyed.

The vacuum suction device 36 is provided with a plurality (three in FIGS. 7 and 8) of suction pads 36A of silicon or the like at the tip of the transfer arm 36B, and applies a negative pressure to the suction pad 36A to form a disk shape. The opposite side of the information recording surface 12A of the substrate material 12 is adsorbed. The transfer arm 36B is provided with an escape hole 36C at the center position of the three suction pads 36A so as not to interfere with the sprue runner 14 of the sucked disk-shaped substrate material 12.

Next, with reference to FIGS. 5 and 6, each step will be described in the case where the information layer transferred by the stamper is provided on the protruding side of the sprue runner in the same manner as described above.

As shown in FIG. 6, in the mold device 40 in this case, the stamper 10 is provided on the fixed mold 42 side,
Moreover, the periphery of the gate 43 is surrounded by the stamper retainer 46 passing through the through hole 10.

Therefore, in the disc-shaped substrate material 12, the information recording surface 12A is formed on the same side as the sprue runner 14 as shown in FIG. 5 (B).

When the spin coating method is used for the disc-shaped substrate material 12 as described above, the sprue runner 14 is provided at the center of the portion where the disc-shaped substrate material is installed. On top, while rotating the disk-shaped substrate material 12 in a horizontal plane, the resin material (light-transmissive resin) flows down from the nozzle 20 to the vicinity of the spool runner 14, and the resin layer (light-transmissive resin) is applied on the film 18. The resin layer) 22 (see FIG. 5E) may be formed.

As disclosed in Japanese Unexamined Patent Publication No. 10-249264, in order to make the thickness of the resin layer to be formed as uniform as possible, the resin material should be made to flow as close to the spool runner as possible. do it.

In the case of the sputtering method, FIG.
As shown in (C), the outer circumference is the outer circumference mask 1 as usual.
Although masking is possible with No. 3, the inner peripheral mask cannot be used. Furthermore, since the protruding portion protrudes toward the sputtering target side, it is necessary to form an escape portion (as indicated by a broken line) in the vicinity of the central portion of the disk-shaped sputtering target.

Thereafter, the manufacturing method shown in FIG. 1 may be used.

In FIG. 5, the injection-molded disc-shaped substrate material 12 is conveyed in the inner peripheral portion or outer periphery of the surface opposite to the side on which the sprue runner 14 is formed, that is, the information recording surface 12A side. Understand the department. For example, the vacuum suction device 36 may suck and convey the inner peripheral portion of the information recording surface 12A of the disk-shaped substrate material 12 or mechanically chuck the outer peripheral portion. Alternatively, the sprue runner 14 may be grasped and conveyed.

In the example of the embodiment shown in FIG. 1, in the final step, the disc-shaped substrate material 12 is formed by an ultrasonic pressing device.
Although the central portion 26 is punched out, the present invention is not limited to this, and various punching methods may be applied.

In the method of manufacturing the disk substrate according to the example of this embodiment, the mask for covering the central hole 28 of the disk-shaped substrate material 12 in the spin coating step is not necessary, and the mask and its replacement member The attaching and detaching process can be omitted. Furthermore, since there is no mask, it is possible to suppress the occurrence of bubbles and uneven streaks in the coating material during spin coating, and thus it is possible to record and / or reproduce from the same direction when the resin layer to be formed is used as a light transmission layer. This is advantageous when forming a spacer layer (a layer between the first recording layer and the second recording layer) of a two-layer disc.

Further, since the central portion 26 is punched out in the final step, it is possible to suppress the adverse effect on the spin coating step and the sputtering step due to dust generated by dropping off burrs during conventional molding.

[0077]

Example 1 An optical disc having a resin layer as a light transmitting layer was manufactured as follows.

First, similarly to the case shown in FIG. 6, a stamper formed beforehand with information was separately fixed to a fixed mold in the mold of the injection molding machine. Here, the molten resin material is supplied from near the center of the fixed mold side through the center hole of the stamper, and the disk-shaped substrate material is formed by the cavity formed by the mirror surface of the movable mold and the like. A center hole forming insert was provided near the center of the movable mold so that the center hole could be formed near the center of the disk-shaped substrate material by punching.

In the step of injecting the resin into the cavity, in forming the disk-shaped substrate material, the mold closing time was 0.3 seconds, and the resin filling into the cavity was 0.35.
Seconds and the holding pressure time was set to 0.6 seconds.

On the other hand, by the delay timer, 0.45 seconds after the start of injection, the center hole molding insert was moved forward to raise the center hole by 0.3 mm in about 0.1 seconds. As a result, a central hole was formed in the central portion of the disk-shaped substrate material by the central hole forming insert, and the central hole was once pushed out above the central hole. The holding pressure is terminated in the middle of the removal process by the center hole molding insert. Around the end of the holding pressure, a cooling step for about 10 seconds was provided.

On the other hand, the center hole molding insert was subjected to a returning process for 10 seconds immediately after the removal process was completed.

When the tip of the insert for molding the central hole returns, the central part is pushed back together with the sprue runner into the central hole of the disk-shaped substrate material due to the pressure difference in the mold device.

When cooling was completed and the mold was opened, a disk-shaped substrate material integrated with the central portion and the sprue runner was formed. That is, the central hole was closed by the central portion.

A recording layer was formed on the information area formed on the side where the spool runner protruded of the disk-shaped substrate material formed as described above. Here, in order to record / reproduce information from the light transmitting resin layer side formed in the subsequent step, a general phase change type recording layer was formed by the reverse sputtering method. Since the spool runner protruding during sputtering interferes, a relief portion was formed near the center of the target. To form the phase-change recording layer, first, a reflective film made of a metal film was formed, and then a general GeSbTe-based recording film was formed so as to be sandwiched by a dielectric layer.

A light transmissive resin layer was further formed thereon. When forming a light-transmissive resin layer, usually, positioning is performed by the center hole and resin coating is performed by the spin coating method. However, since the center hole is not formed here, a slight step difference near the center hole is formed. The disk-shaped substrate material is fixed by suctioning it from the side opposite to the recording layer, and the resin is made to flow down near the spool runner and rotated to spread it all over and irradiated with ultraviolet rays (UV). To cure, about 100μ
m transparent resin layer was formed.

After that, the central portion that closes the central hole is
The optical disc was completed by removing it by sticking it out from the opposite side of the sprue runner.

The optical disc completed in this manner has a simple rotation operation during spin coating as compared with the conventional resin layer forming method, and since the resin is made to flow down from the vicinity of the central portion, it is substantially uniform in the radial direction. Compared with the method using a lid-shaped member, it is possible to form a resin layer, and there is no need for a new material such as a lid, so it is possible to simplify the process and reduce the waste. The effect was obtained.

[0088]

[Embodiment 2] An optical disc having a resin layer as a light transmitting layer is prepared in the same manner as in Embodiment 1 except that the stamper is fixed to a movable die in an injection molding machine die as shown in FIG. It was made.

A recording layer was formed on the information area formed on the side opposite to the side where the spool runner protruded of the disk-shaped substrate material formed under the same conditions as in Example 1. Since the protruding spool runner does not get in the way at the time of sputtering, it is not necessary to form an escape portion near the center of the disk-shaped substrate material installation member.

On the film formed by sputtering,
A light transmissive resin layer was formed. Here, a relief portion was formed near the center of the disk-shaped substrate material installation member of the spin coater. Then, positioning is performed by the step near the center hole formed by the spool runner protrusion,
To fix the disk-shaped substrate material by sucking it in the vicinity of the center, to flow the resin down to the vicinity of the center formed with a slight step, and to rotate it to spread it all over and to irradiate it with ultraviolet rays (UV). Cured by about 10
A 0 μm light transmissive resin layer was formed.

After that, the central part that closes the central hole is
The optical disc was completed by sticking it out from the side of the formed light-transmissive resin layer to complete the optical disc.

The optical disc completed in this way is easier to rotate during spin coating as compared with the conventional resin layer forming method, and moreover the resin is made to flow down from almost the central portion, so that the optical disc is further improved than in the first embodiment. It is possible to form a resin layer that is almost uniform in the radial direction, and it is possible to simplify the process because there is no need for a new material such as a lid, as compared with the method using a lid-shaped member, and it is possible to dispose of it. The multiple effect that there are few things was obtained.

FIG. 9 shows the relationship between the film thickness and the radial position of a disk-shaped substrate material coated with a light-transmitting resin layer (UV resin) according to the first and second embodiments. It is shown in comparison with the case of the disc-shaped substrate material. The lower part of FIG. 9 shows the relationship between the film thickness of the protective coat and the position in the disk radial direction.

As can be seen from FIG. 9, in the case of the conventional disk-shaped substrate material having the center hole, the film thickness of the light-transmissive resin layer is thin at the inner position in the disk radial direction, and becomes thicker toward the outer side in the radial direction. In the case of the present invention, the film thickness of the disk-shaped substrate material is uniform regardless of the radial position.

[0095]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, it is possible to form a resin layer having a relatively large layer thickness of about 100 μm as a layer thickness that is substantially uniform in the radial direction, and separately. Since it is not necessary to use a lid-shaped member, it is possible to simplify the process, and there are multiple excellent effects that the amount of waste is small.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a method for manufacturing an optical disc according to an example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a mold device used in the manufacturing method.

FIG. 3 is a schematic cross-sectional view showing a center hole forming step and its closing step in the mold apparatus.

FIG. 4 is a time chart showing the same process.

FIG. 5 is a schematic perspective view similar to FIG. 1, showing a second example of the embodiment of the manufacturing method.

FIG. 6 is a cross-sectional view showing a mold device in the manufacturing method.

FIG. 7 is a perspective view showing a main part of a vacuum suction device for transporting a disk-shaped substrate material, which is used in the process of the manufacturing method of the present invention.

FIG. 8 is a side view showing a state in which the disk-shaped substrate material is adsorbed by the same device.

FIG. 9 is a diagram showing the relationship between the film thickness of a light-transmitting resin layer and the radial position of the disk in a disk-shaped substrate manufactured by the method of the embodiment of the present invention, as compared with the conventional example.

[Explanation of symbols]

10 ... Stamper 10A ... through hole 12 ... Disk-shaped substrate material 12A ... Information recording surface 14 ... Sprue Runner 16 ... Film forming material 18 ... Membrane 20 ... Nozzle 22 ... Light-transmissive resin layer 24 ... Protective layer 26 ... central part 28 ... Center hole 30, 40 ... Mold device 32, 42 ... Fixed mold 33, 43 ... Gate 34, 44 ... Movable mold 35, 45 ... Center hole forming insert 36 ... Vacuum suction device

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Claims (4)

[Claims] 1. A disk-shaped injection-molded substrate material made of a synthetic resin is formed with a center hole to form a center hole, and the center portion of the substrate material once drawn into the center hole is slightly moved in the thickness direction. By inserting and fitting, the central hole is closed, and
A method for manufacturing an optical disc, characterized by being integrated with a substrate material. 2. The mold for producing the disk-shaped substrate material according to claim 1, comprising a fixed mold and a movable mold,
This movable mold is provided with a center hole molding insert that can move back and forth with respect to the fixed mold, and after the synthetic resin is injected from the gate of the mold into the cavity, the center hole molding insert is moved in the fixed mold direction. To a central hole of the disk-shaped substrate material under pressure retention in the cavity together with a sprue runner in the gate to form a central hole, and then the central part is formed into the central hole. A method of manufacturing an optical disk, characterized in that the disk-shaped substrate is held and taken out from the mold device through a pressing-back step of slightly pressing back to close the central hole and integrating with the disk-shaped substrate material. 3. The method according to claim 1, wherein a step of forming a recording layer at the time of the injection molding on the disc-shaped substrate material integrated with the sprue runner in the gate at the time of the injection molding and the light transmission after the injection molding. Of at least one of the steps of forming a functional resin layer. 4. The sprue runner together with the central portion of the disk-shaped substrate material according to claim 3, after at least one of the step of forming the recording layer and the step of forming the light-transmissive resin layer. A method of manufacturing an optical disk, comprising the step of removing the disk-shaped substrate material to form a central hole.