JPH08124223A - Production of optical disc - Google Patents

Abstract

PURPOSE: To attain mass production of an optical disc at low cost by laminating a synthetic resin film on a planar translucent board, making a central hole therein and transferring protrusions and recesses, representative of information, thereto using a stamper having a central hole. CONSTITUTION: A translucent board 1 is produced by an arbitrary molding method, a synthetic resin film layer 2 is laminated thereon and a central hole 6 is made therein at the time of completion. A stamper 7 having a central hole 8 larger than the central hole 6 and provided with protrusions and recesses 105 representative of information is prepared. The film layer 2 is then superposed on the stamper 7 while facing the surfaces thereof and then they are fitted over a centering member 9 for transfer and pressed thus transferring the protrusions and recesses 105 to the surface of the film layer 2. The central hole 6 is fitted over the centering member 12 for adjustment and the outer circumferential part is subjected to punching. Finally, a reflective film 3 and a protective layer 4 are formed on the film layer 2 transferred with the protrusions and recesses 105 thus completing an optical disc. Consequently, the birefringence of optical disc can be made uniform easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical disk, and more specifically, it can mass-produce an optical disk having excellent optical characteristics and mechanical characteristics efficiently and at low cost. In addition, the present invention relates to a method for manufacturing an optical disc, which can be performed in a short time and can easily prevent the center hole, the transfer position of the information signal, and the eccentricity of the outer peripheral shape.

[0002]

2. Description of the Related Art Optical discs that reflect irradiated laser light in accordance with recorded information signals have come to be widely used as recording media for, for example, audio and video.

For example, as shown in FIG. 6, as a structure of this optical disc, a reflection film 3 for reflecting light is formed on a light-transmissive substrate 1 on which irregularities 5 such as pits and grooves corresponding to information signals are directly formed. Is generally laminated, and a protective film 4 is further laminated on the reflective film 3 in general. And
Conventionally, in the manufacture of optical disks, a synthetic resin such as polycarbonate is used as a raw material, and injection molding is performed using a mold having a built-in stamper, which is a master for information signals, to manufacture a light-transmissive substrate and to form irregularities, which are information signals. (Duplicate)
Were going at the same time.

However, in the case of the above-mentioned manufacturing method, it is necessary to heat and melt the raw material resin, inject it into the mold containing the stamper, and cool it while applying a considerably high pressure. For this reason, the process is complicated and the manufacturing equipment becomes large-scale, the mechanical characteristics are deteriorated due to the warp of the light-transmissive substrate, and the birefringence of the molded product is caused by the flow strain and the uneven pressure distribution during the process. There is also a problem in that the optical characteristics are deteriorated due to non-uniformity and the like. In particular, when performing high-density recording / reproduction, how to improve mechanical properties and optical properties becomes more important in order to improve the performance of the optical disc.

On the other hand, if the cooling time in the injection molding process is sufficient, non-uniformity of birefringence can be reduced to some extent, but it is also necessary to shorten the process time and molding cycle to improve the production efficiency. It is required to shorten the time as much as possible.

Therefore, an optical disk transfer sheet obtained by laminating a thermoformable resin layer on a substrate and heating and pressing a stamper on the surface of the thermoformable resin layer to transfer the unevenness as an information signal is a transparent acrylic resin. A method of manufacturing an optical disk by adhering it to a light-transmissive substrate such as a plate has been proposed (Japanese Patent Laid-Open No. 1-138636). According to this method, the steps can be simplified, the scale of the manufacturing apparatus can be reduced, and deterioration of mechanical characteristics and optical characteristics can be prevented.

By the way, in this method, after the optical disk transfer sheet on which the unevenness as the information signal is transferred is adhered to the light transmissive substrate, the center position is determined with reference to the track of the information signal, and then the center hole is formed. The work procedure is to adjust the outer diameter and shape to form a donut disc. However, the work of determining the center position with reference to the track of the information signal is complicated and time-consuming, and the workability is poor.

[0008]

SUMMARY OF THE INVENTION The present invention was devised in view of the above circumstances, and an object thereof is to mass-produce optical disks having excellent optical characteristics and mechanical characteristics efficiently and at low cost. To provide a method for manufacturing an optical disk, which can easily perform centering of a disk in a process in a short time, and can easily prevent eccentricity of a center hole, a transfer position of an information signal, and an outer peripheral shape. is there.

[0009]

In order to solve the above problems, in the present invention, (a) a first step of preparing a light transmissive substrate having a central hole and laminated with a synthetic resin film layer. And (b) a second step of preparing a stamper having a central hole and in which information is formed in an uneven shape, and (c)
The surface of the synthetic resin film layer and the surface of the stamper face the central hole of the light transmissive substrate with the synthetic resin film layer obtained in the first step and the central hole of the stamper obtained in the second step. A third step of centering the light transmissive substrate with the synthetic resin film layer and the stamper by fitting the same centering member for transfer so as to overlap each other in a state; The optical disk manufacturing method is configured so as to have a fourth step of transferring the unevenness of the stamper surface to the surface of the synthetic resin film layer by pressing the stamper against the synthetic resin film layer after centering.

As a preferred structure, a synthetic resin film layer-attached light-transmissive substrate, in which a thermoplastic resin film layer is laminated as the synthetic resin film layer in the first step, is prepared, and in the fourth step, the stamper is used. Or, as another suitable configuration, in the first step, in the outer peripheral portion of the surface having a disk shape, and a synthetic resin film layer is laminated,
A light-transmitting substrate having a synthetic resin film layer was prepared using a light-transmitting substrate having a tapered surface having a height difference within the thickness of the synthetic resin film to be laminated.

Further, as a preferred structure when the light-transmitting substrate with a synthetic resin film layer obtained in the first step is in the form of a sheet, (e) after the transfer in the fourth step, the synthetic resin is used. By fitting the center hole of the light-transmitting substrate with the film layer to the centering member for adjusting the outer diameter, the light-transmitting substrate with the synthetic resin film layer is centered, and then the unnecessary outer peripheral portion is removed. The optical disk manufacturing method is configured so as to include a fifth step of forming a disk shape.

Further, as a preferable constitution when the transfer in the fourth step is carried out by a flat pressure method, a light transmitting substrate with a synthetic resin film layer and a flat plate on the light transmitting substrate side with the synthetic resin film layer are provided. The method of manufacturing an optical disk is configured so that a stamper is pressed against the synthetic resin film layer by pressing with a foaming resin plate that expands and contracts only in the pressing direction interposed therebetween.

[0013]

In the present invention, the production of the light-transmissive substrate and the formation (reproduction) of the irregularities such as pits, which are information signals, are not carried out at the same time. First, injection molding using a mold without a stamper or other extrusion is performed. After making a simple light-transmitting substrate with no unevenness by a molding method such as molding,
Laminate a synthetic resin film layer to be the unevenness forming layer, and transfer the unevenness by pressing a stamper on the surface of which the information is formed in the shape of unevenness, so that the process and condition setting Can be simplified and the scale of manufacturing equipment can be reduced.

Further, in the case of directly forming the unevenness on the light transmissive substrate, it is necessary to perform injection molding under a high pressure using a complicated mold having the unevenness, but in the present invention, a low pressure is applied. Since the light-transmissive substrate can be manufactured by performing injection molding or a molding method other than injection molding, the mechanical properties of the light-transmissive substrate are not deteriorated. Since distortion and non-uniformity of pressure distribution are less likely to occur, non-uniformity of birefringence of the molded product is less likely to occur, and it is not necessary to take a long cooling time.

Therefore, it becomes possible to mass-produce optical discs having excellent optical characteristics efficiently and at low cost. Further, in the present invention, the central holes of the light-transmitting substrate with the synthetic resin film layer and the central region of the stamper are provided in advance, and the two central holes are formed in a cylindrical shape or the like. Since the unevenness is transferred after the centering is performed by fitting it to the same transfer centering member having the shape of, the optical disc of the optical disk can be simply determined by accurately determining the position when the center hole of the stamper is provided. The center position of the light-transmitting substrate with the synthetic resin film layer to be the center hole and the transfer position of the information signal can be easily centered. Therefore, it is not necessary to individually perform the complicated and time-consuming position determination and centering on the basis of the track of the information signal for each light-transmissive substrate with the synthetic resin film layer on which unevenness has been transferred, thereby improving the production efficiency. It can be further improved.

Further, preferably, when a thermoplastic resin film layer is laminated as the synthetic resin film layer and the stamper is heated and pressed, the film layer is immediately cooled and solidified in the atmosphere after the stamper is peeled off. Since it is not necessary to cure the film layer after forming the unevenness which is a signal, the production efficiency can be further improved.

When the light transmissive substrate has a disk shape having the same dimensions as the optical disc intended as the final product, it is preferable that the synthetic resin film layer of the light transmissive substrate be laminated. By forming a tapered surface having a height difference within the thickness of the synthetic resin film to be laminated on the outer peripheral portion of the surface, the light transmissive substrate and the synthetic resin film to be laminated thereon are formed. Also, since uniform and stable adhesion can be obtained between the light transmissive substrate with a synthetic resin film layer and the stamper, it is possible to reliably prevent and reduce the formation of bubbles and untransferred areas on the outer circumference of the optical disc. You can

When the light-transmitting substrate with the synthetic resin film layer obtained in the above first step is in the form of a sheet, it is preferable that the synthetic resin film layer transferred in the fourth step is attached. By fitting the light-transmitting substrate to the centering member for adjusting the outer diameter, which has a cylindrical shape, etc., the unnecessary outer peripheral part is removed by punching, etc. It can be done easily. Therefore, even at the stage of adjusting the shape of the outer peripheral portion, it is not necessary to individually perform the complicated and time-consuming position determination and centering with respect to the track of the information signal for each synthetic resin film layer-attached light-transmissive substrate. The efficiency can be further improved.

When the transfer in the fourth step is carried out by the flat pressing method, it is preferable that the synthetic resin film layer-provided light-transmitting substrate and the synthetic resin film layer-equipped light-transmitting substrate side are flat. By applying pressure with a foaming resin plate that expands and contracts only in the pressing direction as a cushion layer interposed between the face plate and the face plate, uniform and stable between the light transmissive substrate with a synthetic resin film layer and the stamper. Since the adhesion is obtained, it is possible to prevent the generation of the untransferred portion. Moreover, as compared with the case of using a cushion that expands and contracts in the lateral direction with respect to the pressing direction, it is possible to prevent many scratches from being radially generated from the center on the reading surface of the optical disc.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of an optical disc obtained by the manufacturing method of the present invention, in which a synthetic resin film layer in which irregularities 5 corresponding to information signals are formed on a light-transmissive substrate 1. 2, the reflective film 3 and the protective layer 4 are sequentially stacked. FIG. 1 shows an optical disc in which pits are formed as the irregularities 5 corresponding to information signals on the synthetic resin film layer 2, but the synthetic resin film layer 2 may have grooves. . The shape and size of the optical disc are appropriately determined according to the application of the optical disc. For example, in the case of a compact disc (CD), the diameter is 120 mm.
It has a disk shape with a central hole having a diameter of 15 mm at the center, and its thickness is usually about 1.2 mm.

FIG. 2 is an explanatory view showing an example of the steps of the method for manufacturing an optical disc of the present invention, more specifically an explanatory view showing the steps for manufacturing the compact disc (CD). In the method of the present invention, first, as shown in the upper part of FIG. 2 (a), a light-transmissive substrate 1 having a central hole 6 and a synthetic resin film layer 2 laminated, that is, with a synthetic resin film layer. A light transmissive substrate is prepared (first step). As a light-transmissive substrate with a synthetic resin film layer for producing a compact disc (CD), for example, a polycarbonate (PC) substrate having a thickness of 1.15 to 1.25 mm has a thickness of 25 to 100 μm. Preferably 50 μm
Acrylic polymer film layers are laminated, and the diameter is approximately the same as a compact disc (CD) in the central area 1
A laminate having a sheet shape having a central hole of 5 mm formed therein and having a size capable of adjusting the outer peripheral shape to a disk shape having a diameter of 120 mm by punching or the like is prepared.

For the light-transmitting substrate with the synthetic resin film layer, the light-transmitting substrate 1 is manufactured by an arbitrary molding method such as injection molding or extrusion molding, and the synthetic resin film is wet on the light-transmitting substrate. After laminating by laminating, dry laminating, hot laminating, etc., or extruding molten synthetic resin by laminating, etc., the center hole 6 that should be the center hole of the optical disk at the time of completion is punched out. It is obtained by forming by a method.

The light-transmitting substrate may be made of any material as long as it has a light-transmitting property, and examples thereof include resins such as polycarbonate (PC) and polymethylmethacrylate (PMMA), and transparent materials such as optical glass. To be Among various transparent materials, polycarbonate (PC) is preferably used because it has excellent environment resistance and dimensional stability.

The synthetic resin film laminated on the surface of the light transmissive substrate 1 has good adhesiveness to the light transmissive substrate 1,
It is desirable that the unevenness can be accurately duplicated by the pressure contact of the stamper, and that it is hard to be damaged or deformed after the duplication. Specifically, a thermoplastic resin film, a dry photocurable resin film, or the like can be used. However, when a thermoplastic resin film is used, unevenness such as pits on the stamper in the fourth step described later is used. Is transferred by thermal deformation of the surface of the synthetic resin film layer and is cooled in the atmosphere immediately after the stamper is peeled off, and the unevenness that is an information signal remains on the film as it is, so dry photocurability that requires a curing process by UV irradiation is required. Transfer can be performed more efficiently than when a resin is used.

As a suitable thermoplastic resin film,
An acrylic polymer film having a thickness of 25 to 100 μm, preferably 50 μm can be exemplified. This acrylic polymer film is obtained by blending a polymethylmethacrylate resin (PMMA) with an acrylic rubber resin, and corresponds to "Acryprene HBE" and "Acryprene HBS" manufactured by Mitsubishi Rayon Co., Ltd.

The method of laminating the synthetic resin film on the light transmissive substrate 1 is not particularly limited as described above, but in the case of laminating the film by the pressure roller method as shown in FIG. , Transparent substrate 1 and synthetic resin film 1
02 is inserted between the over-roll 10 and the under-roll 11, and the pressure is gradually linearly contacted from the end.
Air is unlikely to be trapped between the two, and the appearance and reproduction characteristics are good.

When laminating the films by the flat pressing method as shown in FIG. 4 (b), it is preferable that the film is placed between the light transmissive substrate 1 and the flat plate 16 on the light transmissive substrate side. By applying pressure with the foaming resin plate that expands and contracts only in the pressing direction as the cushion 17 interposed, the light transmitting substrate 1
On the reading surface of the optical disc as compared with the case where a cushion that can obtain uniform and stable adhesion between the film and the synthetic resin film 102 and that expands and contracts in the lateral direction with respect to the pressing direction. It is possible to prevent many scratches from radiating from the center. Examples of the foamable resin plate that expands and contracts only in the pressing direction include foamed polyurethane and the like. Its thickness is usually 0.2
˜2.0 mm, preferably 0.5 to 1.0 mm. In addition, when laminating the film by the flat pressure method, by pulling the film in at least four directions,
The occurrence of wrinkles and poor adhesion of the film can be reduced.

The light transmissive substrate with a synthetic resin film layer prepared in the first step does not necessarily have to have the same size and shape as the completed optical disc.
It may have a sheet shape as shown in (a). In that case, it is necessary to adjust the shape and size of the outer peripheral portion at any stage after the first step. When the light-transmissive substrate has a disk shape with the same dimensions as the optical disk intended as the final product, the synthetic resin film layers of the light-transmissive substrate are preferably laminated as shown in FIG. A tapered surface 14 having a height difference h within the thickness of the synthetic resin film to be laminated is formed on the outer peripheral portion of the surface on the side where the film is made. By doing so, in the first step, between the light-transmitting substrate 1 and the synthetic resin film 102 laminated thereon, and in the fourth step, between the light-transmitting substrate with the synthetic resin film layer and the stamper. Thus, uniform and stable adhesion can be obtained, so that it is possible to reliably prevent and reduce the occurrence of bubbles and non-transferred portions on the outer peripheral portion of the optical disc.

Since the center hole 6 of the light-transmitting substrate with the synthetic resin film layer is the center hole of the completed optical disk, its shape and size must be the same as the center hole of the completed optical disk. Regarding the position where the central hole 6 of the synthetic resin film layer-equipped light transmissive substrate is formed, the synthetic resin film layer-equipped light transmissive substrate having the same shape and size as the completed optical disc as shown in FIG. 3B. It is necessary to accurately determine the center position when preparing a disc, but when preparing a disc having a different shape and size from the completed optical disc as shown in FIG. Since the centering can be performed in the adjustment step of, it is not always necessary to accurately determine the center position.

Next, as shown in the middle part of FIG. 2A, a stamper 7 having a central hole 8 and in which information is formed in the form of unevenness 105 is prepared (second step). The stamper 7 is usually made of metal such as nickel (Ni). The center hole 8 of the stamper is different from the center hole 6 of the light-transmitting substrate with a synthetic resin film layer, and it is necessary to form the center position accurately, but the shape and size of the stamper are the same as the finished optical disc. Can be determined independently of the central hole of the. For example, the center hole 8 of the stamper shown in the middle part of FIG. 2A has a larger diameter than the center hole 6 of the light-transmitting substrate with the synthetic resin film layer in the upper part.

Next, as shown in FIG. 2 (b), the central hole of the light-transmitting substrate with a synthetic resin film layer obtained in the first step and the central hole of the stamper obtained in the second step are separated. By fitting into the same transfer centering member 9 so that the surface of the synthetic resin film layer 2 and the surface of the stamper 7 face each other, the light transmissive substrate with the synthetic resin film layer is formed. Centering with the stamper is performed (third step), and then the stamper 7 is pressed against the synthetic resin film layer 2 to transfer the unevenness 105 of the stamper surface to the surface of the synthetic resin film layer 2 (first step). Four steps). When a dry photo-curable resin film is used as the synthetic resin film, the stamper is pressed and then irradiated with ultraviolet rays to cure the synthetic resin film layer, and then the stamper is peeled off.

Regarding the shape and size of the centering member 9 for transfer, both the central holes of the light transmissive substrate with a synthetic resin film layer and the center hole of the stamper play (center) It is not particularly limited as long as it can be freely fitted without generating a gap between the aligning member and each central hole). For example, the transfer centering member 9 shown in the lower part of FIG.
Has a large-diameter cylindrical structure in which the central hole 8 of the stamper fits snugly in the lower part, and a small diameter in which the central hole 6 of the light-transmitting substrate with a synthetic resin film layer fits snugly in the upper part. And the central axes of both the upper and lower cylindrical structures are on the same straight line.

The method of pressing the stamper 7 against the surface of the synthetic resin film layer 2 is not particularly limited, and other than the pressure roller method shown in FIG. 2 (b), for example, the flat pressure method shown in FIG. May be adopted. When the transfer is performed by the pressure roller method as shown in FIG. 2B, the synthetic resin film 102 is formed on the transparent substrate 1 in the first step.
In the same manner as in the case of laminating, the air is unlikely to be trapped between the synthetic resin film layer 2 and the stamper 7, so that the appearance and the reproduction characteristics are improved.

For example, in the case of the polycarbonate substrate provided with the acrylic polymer film layer prepared in the first step, the surface temperature of the metal stamper such as nickel (Ni) is 100 to 140 ° C., preferably 110 ° C. Pressure is 45 to 200 kg / cm ² , preferably 90 kg
/ Cm ² , it is preferable to perform thermal transfer by a pressure roller method. Here, the surface temperature of the stamper 7 is set to 100 to 14
The temperature of 0 ° C. is the heat distortion temperature of polycarbonate (14
This is to ensure a sufficiently high temperature for transferring onto the acrylic polymer film layer within a range not exceeding (0 ° C.).

The uniformity of transfer depends on the surface temperature of the stamper,
It depends on the heat distortion temperature of the film, the applied pressure, and the thickness of the film. Describing along with the above-described specific example, the surface temperature of the stamper 7 needs to be high so that the film can be sufficiently deformed, but the surface temperature is raised too high to be near the heat deformation temperature of the polycarbonate substrate or higher. If so, the light transmissive substrate (polycarbonate substrate) 1 is thermally deformed, and mechanical properties such as warpage are deteriorated and birefringence is deteriorated. Therefore, it is preferable to keep the temperature at 120 ° C. or lower. The heat distortion temperature of the acrylic polymer film is preferably 100 ° C. or lower from the viewpoint of sufficiently transferring at a stamper surface temperature of 120 ° C. or lower.
If the heat distortion temperature is 70 ° C. or lower, the heat resistance guaranteed temperature of the optical disk, which is a product, cannot be cleared in many cases.
It is preferable that the temperature is not lower than ° C. There is a close relationship between the pressing force and the film thickness, and the heat conduction deteriorates as the film becomes thicker, so the pressing force of the roller must be increased.

When the unevenness 5 is duplicated by thermal transfer, the depth of the unevenness 5 formed on the synthetic resin film layer 2 is closely related to the stamper temperature, the transfer pressure, and the pressurizing time. It has the highest pressure and pressure time. Further, when the stamper 7 is peeled from the synthetic resin film layer 2, the film layer 2 is thermally contracted, so that the depth of the unevenness 5 is reduced. For these reasons, the reproduction signal can be optimized by adjusting the depth of the unevenness 105 of the stamper 7, which is the original plate, in advance.

Further, in the flat pressing method shown in FIG.
The transfer centering member 9 existing at the center of the signal transfer mold is supported by a spring 18 having a spring constant in the range of 3 to 25 kg / mm, and the lower part thereof has a large size into which the center hole 8 of the stamper fits closely. It has a cylindrical structure with a diameter, and the upper part has a small diameter cylindrical structure in which the central hole 6 of the light-transmitting substrate with a synthetic resin film layer fits snugly, and both upper and lower cylindrical structures. The central axes of are on the same straight line. Then, the centering member 9 for transfer is sequentially fitted into both center holes of the stamper and the light transmissive substrate with the synthetic resin film layer to perform centering. At this stage, as shown in FIG. 5A, the light-transmitting substrate with the synthetic resin film layer is on the stepped portion of the transfer centering member 9, and the stamper and the light-transmitting substrate with the synthetic resin film layer are attached. There are spaces 20 at regular intervals between the substrates.

After centering, as shown in FIG. 5B, when the upper flat plate 16 having sufficient rigidity is lowered and pressure p is applied, the transfer centering member 9 and the synthetic resin film The layered light-transmissive substrate is pushed by the upper flat plate 16 and descends, and the stamper surface and the synthetic resin film layer are brought into close contact with each other. At this time, the lowering of the transfer centering member 9 is stopped by a stopper capable of withstanding the pressing force p at the time when the stamper surface and the film layer surface are pressed down to each other, and as a result, it is appropriately strong and uniform. Adhesion strength is secured. Here, it is preferable that a cushion 17 such as soft rubber is attached to the lower surface of the upper flat plate 16 so as not to scratch the surface of the light transmissive substrate 1. In particular,
If a foamable resin plate that expands and contracts only in the pressing direction is used as the cushion, it is possible to prevent many scratches from being radially generated from the center on the reading surface of the optical disc.
Here, as the foamable resin plate that expands and contracts only in the pressing direction,
For example, foamed polyurethane can be exemplified,
The thickness is usually 0.2 to 2.0 mm, preferably 0.5.
~ 1.0 mm.

After the pressing of the stamper is performed as described above, when the pressing force p is removed and the upper flat plate 16 is raised, the transfer centering member 9 rises by the force of the spring and rides on the stepped portion. The light-transmitting substrate with the synthetic resin film layer is instantly peeled off from the stamper 7. As a result, it is possible to reduce mold release stains that occur during peeling.

For example, when the planar pressing method is performed on the polycarbonate substrate with the acrylic polymer film layer prepared in the first step, the stamper is placed on the sufficiently thick lower flat plate 15 heated to about 110.degree. 7 is brought into close contact, and pressure is applied at 80 kg / cm ² or more. Stamper 7
It is preferable that the temperature of the lower flat plate 15 to which is adhered is also sufficiently high to transfer the unevenness 5 to the surface of the acrylic polymer film 102, but this temperature is near the heat deformation temperature of the polycarbonate substrate or higher. If so, the light transmissive substrate 1 is thermally deformed, causing deterioration of mechanical characteristics such as warpage and deterioration of birefringence. The pressing force and pressing time are also important factors, but when the pressing force is 80 kg / cm ² and the pressing time is 3 seconds, the stamper surface temperature is 1
If the temperature is maintained at 00 to 110 ° C, the mechanical properties and the birefringence are not deteriorated.

When the transferred light-transmitting substrate with the synthetic resin film layer obtained by the above-mentioned fourth step is different from the shape or size of the optical disc at the time of completion,
For example, in the case of a sheet shape, the outer peripheral shape or the outer diameter is further adjusted. At this stage,
As shown in (c), the center hole 6 of the synthetic resin film layer-attached light-transmissive substrate removed from the transfer centering member 9 is fitted into the outer diameter adjusting centering member 12, and then the cutter 13 is used. By performing punching using etc., the centering and processing of the outer peripheral shape can be performed extremely easily. Regarding the shape and size of the adjusting centering member 12, the play that causes the displacement of the center hole 6 of the light-transmitting substrate with the synthetic resin film layer with respect to the adjusting centering member 12 (the adjusting centering member). Member 1
2 and the central hole 6 of the light transmissive substrate with the synthetic resin film layer
There is no particular limitation as long as it can be fitted freely without any gap).

For example, in the case of a sheet-shaped polycarbonate substrate with a transferred acrylic polymer film layer having a central hole with a diameter of 15 mm, which is obtained by the pressure roller method or the flat pressure method in the fourth step, A compact disc (CD) is obtained by fitting the center hole 6 into a centering member 12 for adjustment having a cylindrical shape with a diameter of 15 mm, and punching the outer peripheral portion.
Adjust the outer diameter to 120 mm.

Next, as shown in FIG. 2D, a reflective film 3 is formed on the synthetic resin film layer 2 on which the unevenness 5 of the information signal is transferred, and the protective layer 4 is formed on the reflective film 3. By doing so, the optical disc is completed. Examples of materials for forming the reflective film 3 include aluminum (Al), aluminum (Al) alloy, gold (Au), silver (Ag), and copper (Cu). Among these, aluminum (A
l) and aluminum (Al) alloys are preferred. As a method of forming the reflective film 3, for example, a sputtering method,
A vacuum deposition method, an ion plating method and the like can be mentioned. The thickness of such a reflective film 3 is usually 0.03 to 0.
It is 1 μm, preferably 0.03 to 0.05 μm.

Examples of the material for forming the protective layer 4 include epoxy resin, acrylic resin, silicone resin, urethane resin, ethylene-vinyl acetate copolymer resin and the like. Further, this protective layer 4 is a so-called 2P (photo poly
It may be an ultraviolet curable resin applied by a marization method. The thickness of the protective layer 4 is usually 5 to 1
The thickness is 00 μm, preferably 5 to 20 μm.

The reflective film 3 and the protective layer 4 may be laminated before adjusting the outer peripheral shape.

[0046]

EFFECTS OF THE INVENTION According to the method of the present invention, each step such as an injection molding step for a light transmissive substrate and a step for forming irregularities such as pits which are information signals can be performed under advantageous conditions. The cooling time can be shortened, and the birefringence of the optical disk can be easily made uniform. Therefore, according to this method, it is possible to efficiently mass-produce optical discs having excellent optical characteristics at low cost.

By using this method, the center hole of the optical disc, the transfer position of the information signal, and the center of the outer peripheral shape can be aligned very easily and in a short time, and the eccentricity between them can be efficiently performed. Since it can be prevented, many optical disks can be manufactured in a short time.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a layer structure of an optical disc obtained by an optical disc manufacturing method of the present invention.

FIG. 2 is an explanatory diagram showing an example of steps of the optical disc manufacturing method of the present invention.

FIG. 3 is an explanatory view illustrating some shapes of a light-transmitting substrate with a synthetic resin film layer prepared in the first step.

FIG. 4 is an explanatory view illustrating a method of laminating a synthetic resin film layer on a light transmitting substrate.

FIG. 5 is an explanatory diagram showing a procedure in the case where centering and transfer are performed by a planar pressing method in a fourth step.

FIG. 6 is a schematic sectional view showing an example of a layer structure of a conventional optical disc.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light transmissive substrate 2 ... Synthetic resin film layer 102 ... Synthetic resin film 3 ... Reflective film 4 ... Protective film 5 ... Unevenness on synthetic resin film layer 105 ... Unevenness on stamper 6 ... Synthetic resin film layer Center hole of light-transmitting substrate 7 ... Stamper 8 ... Center hole of stamper 9 ... Centering member for transfer 10 ... Over-roll 11 ... Under-roll 12 ... Centering member for adjusting outer diameter 13 ... Cutter 14 ... Tapered surface 15 ... Lower plane plate 16 ... Upper plane plate 17 ... Cushion 18 ... Spring 19 ... Temperature adjustment groove 20 ... Space between synthetic resin film layer and stamper h ... Height difference of taper surface f ... Tension p ... Pressing force

(72) Inventor Yoshitaka Nonaka 2680 Nishi Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Pioneer Video Co., Ltd.

Claims (5)

[Claims] 1. A first step of preparing a light-transmissive substrate having a central hole and laminated with a synthetic resin film layer, and a stamper having a central hole and having information formed in an uneven shape. The second step of preparing, the central hole of the light-transmitting substrate with a synthetic resin film layer obtained in the first step and the central hole of the stamper obtained in the second step, the surface of the synthetic resin film layer A third step of centering the light transmissive substrate with the synthetic resin film layer and the stamper by fitting the same transfer centering member so that the surfaces of the stamper and the surface of the stamper are opposed to each other, and After performing the centering of the third step, by pressing the stamper to the synthetic resin film layer, the unevenness of the stamper surface is transferred to the surface of the synthetic resin film layer Optical disk manufacturing method. 2. A light-transmissive substrate with a synthetic resin film layer, in which a thermoplastic resin film layer is laminated as a synthetic resin film layer, is prepared in the first step, and the stamper is heated and pressed in the fourth step. The method for manufacturing an optical disk according to claim 1, wherein 3. When the light-transmitting substrate with a synthetic resin film layer obtained in the first step has a sheet shape,
After performing the transfer in the fourth step, the center hole of the light-transmitting substrate with the synthetic resin film layer is fitted to the centering member for adjusting the outer diameter to center the light-transmitting substrate with the synthetic resin film layer. The method for producing an optical disk according to claim 1, further comprising a fifth step of removing the unnecessary outer peripheral portion to form a disk shape. 4. When the transfer of the fourth step is carried out by a flat pressure method, a pressure is applied between the light-transmissive substrate with the synthetic resin film layer and the flat plate on the side of the light-transmissive substrate with the synthetic resin film layer. 2. The method for producing an optical disk according to claim 1, wherein the stamper is pressed against the synthetic resin film layer by applying pressure with a foamable resin plate that expands and contracts only in the pressure direction being interposed. 5. In the first step, a height difference within a thickness of the synthetic resin film to be laminated is provided on an outer peripheral portion of a surface having a disk shape and on which the synthetic resin film layer is laminated. 2. The method of manufacturing an optical disc according to claim 1, wherein the light-transmissive substrate having the taper surface is provided to prepare the light-transmissive substrate with the synthetic resin film layer.