JP4305302B2 - Disk substrate manufacturing method and molding die apparatus - Google Patents

Description

The present invention relates to a method of manufacturing a disk substrate that can prevent the occurrence of scratches on an information reading surface , and a molding die device for manufacturing the disk substrate.

  In recent years, there has been proposed an optical recording medium in which information signals are recorded and / or reproduced by irradiating a laser beam not from the disk substrate side but from the side provided with a protective layer for protecting the information signal portion. .

  FIG. 10 is a cross-sectional view showing the configuration of an optical recording medium on which information signals are recorded and / or reproduced from the protective layer side. As shown in FIG. 10, this optical recording medium has an information signal unit 102 configured to record and / or reproduce information signals, and is configured to transmit laser light used for recording and / or reproducing information signals. The light transmission layer (protective layer) 103 is sequentially laminated on a disk substrate 101 having an opening (center hole) 101a at the center.

  Further, in the above-described optical recording medium, it has been proposed to extend the inner peripheral edge of the light transmission layer 103 to the inside of the clamping area 101b in order to improve reliability (for example, refer to Patent Document 1).

  Further, in the above-described optical recording medium, an elevator is provided between the information signal unit 102 and the clamping area 101b (for example, in the range of diameter Φ35 to Φ37 mm), as in the case of a conventional optical recording medium such as a CD (Compact Disc). It has been proposed to provide a projection 104 called an action (stack rib). As described above, since the protrusion 104 cannot be provided on the light transmission layer 103 side when the inner peripheral end of the light transmission layer 103 is extended to improve reliability, the protrusion 104 is different from the light transmission layer 103. It will be provided on the opposite surface.

  However, if the protrusion is provided on the surface opposite to the light transmission layer, the following problems occur when the optical recording medium is used without being stored in the cartridge. That is, conventionally, in a single-plate type optical recording medium such as a CD-R (Recordable), since the protrusion is provided on the information reading surface side, the user can use the optical recording medium with the information reading surface down. Even when placed on a table or the like, it is possible to prevent the information reading surface from being scratched or adhering to dust due to the protrusions. In contrast, in an optical recording medium in which information signals are recorded and / or reproduced from the protective layer side, when the user places the light transmissive layer side down on a table or the like, the surface on the light transmissive layer side, That is, the information reading surface may be scratched or dust may be attached, and as a result, accurate data reading and writing may not be possible.

  Further, if the formation of the protrusions is omitted, the following problems will occur at the time of manufacturing the optical recording medium. In other words, if the disc substrate is not provided with a protrusion, it is necessary to insert a spacer between the optical recording media to be laminated so that the optical transmission layers do not contact each other when the optical recording media are laminated on a pole magazine or the like. It will occur. Therefore, not only a secondary material called a spacer is required, but also a device for inserting and removing the spacer is required, leading to an increase in manufacturing cost of the optical recording medium. Furthermore, the manufacturing tact is also increased by the step of inserting the spacer.

  Therefore, in order to solve the above-described problem, an optical recording medium in which a ring-shaped member is bonded onto a light transmission layer has been proposed (for example, see Patent Document 2).

JP 2002-117484 A

JP 2003-157582 A

  However, this optical recording medium has a problem that the yield is deteriorated due to an increase in the number of processes and the cost is increased. Therefore, in an optical recording medium that records and / or reproduces an information signal by irradiating a laser beam from the light transmitting layer side, a protrusion having the above-described function can be provided without increasing the number of steps and increasing the cost. An optical recording medium that can be used has been awaited.

Accordingly, an object of the present invention is to provide an information signal reading surface in an optical recording medium that records and / or reproduces an information signal by irradiating a laser beam from the light transmitting layer side without increasing the number of steps and increasing the cost. It is an object of the present invention to provide a disk substrate manufacturing method and a mold forming apparatus that can be provided with protrusions that prevent contact scratches and dust from adhering to the substrate .

In order to solve the above-mentioned problem, the invention according to claim 1
A step of molding a disk substrate is solidified to form a cavity corresponding to the shape of the disk substrate by closing the pair of molds to be paired direction, after injecting the resin into the cavity,
Opening the mold and projecting the protrusion formed on the inner periphery of the disk substrate from the mold by the discharging means ;
With
The discharging means is
An annular discharge part protruding from the protrusion;
An air receiving portion provided on the outer periphery of the discharge portion;
With
The discharge part is a method of manufacturing a disk substrate that is movable when the air receiving part receives air .

According to the first aspect of the present invention, since the mold is opened and the protrusion formed on the inner peripheral portion of the disk substrate is protruded from the mold by the discharging means, the protrusion can be easily released from the mold.

The invention according to claim 4
A pair of molds facing each other,
One of the mold,
A mounting surface on which a stamper for forming an information reading surface is mounted ;
A recess for forming a protrusion on the inner periphery of the disk substrate , provided on the inner periphery of the mounting surface on which the stamper is mounted ;
A discharge means for protruding the resin solidified in the recess provided in the recess ;
With
The discharging means is
An annular discharge part protruding from the protrusion;
An air receiving portion provided on the outer periphery of the discharge portion;
With
The discharge part is a molding die device that moves when the air receiving part receives air .

In the invention according to the fourth aspect , since the resin solidified in the recess provided in the inner peripheral portion of the mold is projected by the discharging means, the solidified resin can be easily released from the recess.

According to the first aspect of the present invention, since the mold is opened and the protrusion formed on the inner peripheral portion of the disk substrate is protruded from the mold by the discharging means, the protrusion can be easily released from the mold. Therefore, the protrusion can be formed on the inner peripheral portion of the disk substrate without causing distortion or the like in the disk substrate. Further, when the disk substrate is injection-molded, a protrusion can be integrally formed on one main surface of the disk substrate. Therefore, it is possible to provide a protrusion that prevents contact scratches and dust from adhering to the information signal reading surface without increasing the number of steps and increasing the cost.

In the invention according to the fourth aspect , since the resin solidified in the recess provided in the inner peripheral portion of the mold is projected by the discharging means, the solidified resin can be easily released from the recess. Therefore, the protrusion can be formed on the inner peripheral portion of the disk substrate without causing distortion or the like in the disk substrate. Further, when the disk substrate is injection-molded, a protrusion can be integrally formed on one main surface of the disk substrate. Therefore, it is possible to provide a protrusion that prevents contact scratches and dust from adhering to the information signal reading surface without increasing the number of steps and increasing the cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.

Embodiments of the present invention will be described in the following order.
(1) Configuration of optical recording medium (2) Configuration of molding die apparatus (3) Manufacturing method of optical recording medium

(1) Configuration of Optical Recording Medium FIG. 1 is a cross-sectional view showing a configuration example of an optical recording medium according to an embodiment of the present invention. As shown in FIG. 1, the optical recording medium includes a disk substrate 1, an information signal portion 2 formed on one main surface of the disk substrate 1, and a light transmission layer 3 formed on the information signal portion 2. With.

  In the optical recording medium according to this embodiment, information signals are recorded and / or reproduced by irradiating the information signal portion 2 with laser light from the light transmission layer 3 side. For example, laser light having a wavelength in the range of 400 nm to 410 nm is condensed by an objective lens having a numerical aperture in the range of 0.84 to 0.86, and is transmitted from the light transmission layer 3 side to the information signal unit 2. The information signal is recorded and / or reproduced by irradiation. An example of such an optical recording medium is Blu-ray Disc (registered trademark). Hereinafter, the surface on the side irradiated with the laser beam for recording and / or reproducing the information signal is referred to as an information reading surface.

  The disk substrate 1 has an annular shape with an opening (hereinafter referred to as a center hole) 1a formed in the center. On one main surface of the disk substrate 1 on the side where the information signal portion 2 is formed, irregularities serving as guide grooves for guiding an optical spot when recording and / or reproducing information signals are formed. Using this groove as a guide, the laser beam can move to an arbitrary position on the optical recording medium. Examples of the shape of the groove include various shapes such as a spiral shape, a concentric circle shape, and a pit row. The diameter of the disk substrate 1 is selected to be 120 mm, for example. The thickness of the disk substrate 1 is selected in consideration of rigidity, preferably from 0.3 mm to 1.3 mm, more preferably from 0.6 mm to 1.3 mm, for example, 1.1 mm. . The diameter (radius) of the center hole 1a is selected to be 15 mm.

  Further, an annular clamping area 1b is set around the center hole 1a. The inner diameter (diameter) of the clamping area 1b is selected, for example, 23 mm, and the outer diameter (diameter) is selected, for example, 33 mm.

  An information signal portion forming area 1c for forming the information signal portion 2 and a light transmitting layer forming area 1d for forming the light transmitting layer 3 are set on one main surface where the information signal portion is formed. Has been. The light transmission layer forming area 1d is set wider than at least the information signal portion forming area 1c, and preferably wider than the information signal portion forming area 1c and the clamping area 1b. That is, the inner periphery of the light transmission layer forming area 1d is set at least inside the information signal part forming area 1c, and preferably set inside the clamping area 1b.

  Further, the disk substrate 1 has a projection 4 called an elevation (stack rib) on the surface on which the information signal portion is formed. The protrusion 4 is provided in a region between the center hole 1a and the light transmission layer 3, for example, a region having a diameter of 17.5 mm to 19.5 mm. The height h of the protrusion 4 is selected to be larger than the total thickness of the information signal portion 2 and the light transmission layer 3, and is selected from a range of 0.05 mm to 0.32 mm, for example. The shape of the protrusion 4 is not particularly limited as long as it can hold a space between the light transmissive layer 3 and the table or the like when the table or the like is placed with the light transmissive layer 3 formed side down. For example, an annular shape, a spot shape, and a rib shape can be cited. When the protrusion 4 and the disk substrate 1 main body are integrally formed by injection molding, the shape of the protrusion 4 is preferably an annular shape from the viewpoint of ease of forming the protrusion 4.

  FIG. 2 is a plan view of an optical recording medium provided with an annular protrusion 4 on the information reading surface. As shown in FIG. 2, an annular protrusion 4 centered on the center hole 1 a is provided in a region between the center hole 1 a and the light transmission layer 3.

  FIG. 3 is a plan view of an optical recording medium provided with spot-like protrusions 4 on the information reading surface. As shown in FIG. 3, a plurality of spot-like protrusions 4 are provided in a region between the center hole 1 a and the light transmission layer 3. For example, the protrusion 4 is provided on a virtual circumference having the same center as that of the optical recording medium. Considering the stability when the optical recording medium is placed on a table or the like, it is preferable to make the distances between the adjacent protrusions 4 equal. Similarly, from the viewpoint of stability, the number of the spot-like protrusions 4 is preferably 3 or more.

  FIG. 4 is a plan view of an optical recording medium provided with rib-like protrusions 4 on the information reading surface. As shown in FIG. 4, a plurality of rib-shaped protrusions 4 are provided in the region between the center hole 1a and the light transmission layer 3 so as to follow the center hole 1a.

  As the material of the disk substrate 1, for example, a plastic material such as polycarbonate resin, polyolefin resin, or acrylic resin, or glass is used. In consideration of cost, it is preferable to use a plastic material as the material of the disk substrate 1.

  The information signal unit 2 is a reflective film or a recording film. Examples of the material of the reflective film include metal elements, metalloid elements, compounds or mixtures thereof, and more specifically, for example, Al, Ag, Au, Ni, Cr, Ti, Pd, Co, Si, Examples thereof include simple substances such as Ta, W, Mo, and Ge, or alloys containing these simple substances as a main component. In consideration of practicality, it is preferable to use an Al-based material, an Ag-based material, an Au-based material, a Si-based material, or a Ge-based material among them.

  The recording film is selected depending on whether the optical recording medium is a write-once type or a rewritable type. When the optical recording medium is a write-once type, examples of the recording film include a recording film formed by sequentially laminating a reflective film and an organic dye film on the disk substrate 1. When the optical recording medium is a rewritable type, the recording film is, for example, configured by sequentially stacking a reflective film, a lower dielectric layer, a layer change recording film, and an upper dielectric layer on the disk substrate 1. An example is a recording film. The inner diameter (diameter) of the information signal unit is selected to be 40 mm, for example.

  The light transmitting layer 3 includes, for example, a light transmitting sheet (film) having a planar annular shape, and an adhesive layer for bonding the light transmitting sheet to the disk substrate 1 on which the information signal portion 2 is formed. Consists of The adhesive layer is made of, for example, an ultraviolet curable resin or a pressure sensitive adhesive (PSA).

  The light-transmitting sheet is preferably made of a material having a low absorption ability with respect to laser light used for recording and / or reproduction, specifically, a material having a transmittance of 90% or more. Examples of the material for the light transmissive sheet include polycarbonate resin materials and polyolefin resins (for example, ZEONEX (registered trademark)).

  Further, the thickness of the light transmissive sheet is preferably selected to be 0.3 mm or less, and more preferably selected from the range of 3 to 177 μm. For example, the thickness of the light transmissive sheet is selected so that the total thickness of the light transmissive sheet and the adhesive layer is, for example, 100 μm. By combining such a thin light transmission layer 3 and an objective lens having a high NA (numerical aperture) of about 0.85, high density recording can be realized. The inner diameter (diameter) of the light transmission layer 3 is selected to be 22.7 mm, for example.

(2) Configuration of Molding Device FIG. 5 is a cross-sectional view showing a configuration example of the molding die device according to one embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view showing a configuration example of a molding die apparatus according to an embodiment of the present invention.

  Hereinafter, the molding die apparatus according to the embodiment will be described with reference to FIGS. As shown in FIG. 5, the molding die apparatus includes a fixed mold 11 and a movable mold 21, and these fixed mold 11 and the movable mold 21 are brought into contact with each other. A cavity 31 that is a molding space is formed. In this molding die apparatus, the disk substrate is molded by filling the cavity 31 with the melted disk substrate material.

  The fixed mold 11 includes a fixed mirror 12 on a surface facing the movable mold 21, and a stamper 32 is attached to a surface on which the cavity 31 is formed. In addition, the fixed die 11 is provided with a stamper outer peripheral holder 13 for attaching the stamper 32. The stamper outer peripheral holder 13 is, for example, an annular shape having an opening that is slightly larger than the outer diameter of the cavity 31 and is slightly smaller than the outer diameter of the stamper 32. This stamper outer peripheral holder 13 is assembled to the fixed mold 11 by means of mounting screws or the like.

  The stamper 32 has an annular shape having a center hole, and the main surface 32a is provided with irregularities corresponding to lands, grooves, and the like. The stamper 32 is attached to the fixed-side mold 11 so that the one main surface 32 a side faces the movable-side mold 21. When attaching the stamper 32 to the fixed mold, the outer periphery of the stamper 32 is sandwiched between the stamper outer holder 13 and the fixed mirror 12.

  Further, a sprue bush 14 is provided at a substantially central portion of the fixed side mold 11. The sprue bush 14 has a cylindrical shape, and a resin injection hole 15 is provided at the center thereof. The resin injection hole 15 is connected to a material supply device (not shown). The molten disk substrate material is supplied from the material supply device into the cavity 31 through the resin injection hole 15.

A recess 17 for providing the protrusion 4 on the disk substrate 1 is provided between the fixed mirror 12 and the sprue bush 14. The depth d ₁ of the recess 17 is selected to be the same as the height of the protrusion 4 provided on the disk substrate 1, and is selected in the range of 0.05 mm to 0.32 mm, for example.

  The shape of the concave portion 17 is selected according to the shape of the projection 4 provided on the disk substrate 1, and is selected, for example, in an annular shape around the resin injection hole 15, a spot shape, or a rib shape. In consideration of easiness, it is selected as an annular shape. The recessed part 17 is provided in the area | region between diameter (phi) 17.5mm-19.5mm, for example.

  A fixed-side ejector 16 is provided in the recess 17. The fixed-side ejector 16 is configured to be movable in a direction in which the fixed-side ejector 16 protrudes and is buried with respect to the direction of the movable mold 21. The fixed-side ejector 16 preferably protrudes to the opening position of the recess 17, and the protrusion width is selected in the range of 0.2 mm to 0.5 mm, for example.

  When the movable side mold 21 is moved away from the fixed side mold 11, the fixed side ejector 14 projects toward the movable side mold 21 and discharges the solidified resin in the recess 17. Acts like

  FIG. 7 is an enlarged cross-sectional view showing a configuration example of the fixed-side ejector 16 provided in the molding die device according to the embodiment of the present invention. A space 18 having an L-shaped cross section is provided between the fixed mirror 12 and the sprue bush 14, and the fixed-side ejector 16 is fitted into this space 18. The fixed-side ejector 16 includes an eject portion 16a that discharges the resin solidified in the recess portion 17, and an air receiving portion 16b that receives air and moves the eject portion 16a in a direction in which the eject portion 16a protrudes or is buried.

More specifically, for example, the fixed-side ejector 16 includes an annular ejector portion 16a and an air receiving portion 16b that is provided in a bowl shape on the outer periphery of the fixed-side ejector 16a. Above the air receiving portion 16b, an air receiving portion presser 12a provided so as to protrude from the fixed mirror 12 so as to cover the air receiving portion 16b is provided. A space is provided between the air receiving portion and the air receiving portion presser 12 a, and the width d _{2 of} this space becomes the protruding width of the fixed-side ejector 16.

  One or more air passages 19 are provided on the bottom surface of the space 18, and compressed air is supplied into the space 18 from the air supply device (not shown) through the air passage 19. Further, one or more air passages 20 are provided on the upper surface of the space 18, and compressed air is supplied into the space 18 from the air supply device (not shown) through the air passage 20.

  On the other hand, the movable side mold 21 is disposed to face the fixed side mold 11 and can be moved close to and away from the fixed side mold 11 by guide means (not shown). The movable die 21 has a gate cut punch 24 that cuts the central portion of the disk substrate solidified in the cavity 31 at a substantially central portion thereof, and an extrusion pin 25 that pushes out the central portion cut by the gate cut punch 24. And a movable ejector 23 for releasing the disk substrate from the movable mold.

  The gate cut punch 24 cuts the runner portion of the disk substrate material supplied from the sprue bush 14 into the cavity 31 and solidified, and has an outer dimension substantially the same as the center hole 1a of the disk substrate 1. It has a diameter. The gate cut punch 24 can be moved in a direction protruding into the cavity 31 by guide means or drive means (not shown).

  The extrusion pin 25 is formed in a rod shape and is arranged at the center of the gate cut punch 24. The push pin 25 is movable in a direction protruding into the cavity 31 by a guide means and a drive means (not shown), and removes the portion cut by the gate cut punch 24 described above. Therefore, after the disk substrate material filled in the cavity 31 is solidified, by pushing out the extrusion pin 25, the disk substrate accumulated in the runner portion and the sprue, that is, the supply portion of the runner portion and the sprue bush portion 14. Material can be removed.

  The movable ejector 23 is configured to have a cylindrical shape having an inner diameter substantially the same as the outer diameter of the gate cut punch 24, and is disposed so as to surround the gate cut punch 24. This movable-side ejector 23 can be moved in a direction protruding into the cavity 31 by guide means and drive means (not shown). Therefore, after the disk substrate material is filled in the cavity 31 and the center hole of the disk substrate is formed as described above, the movable-side ejector 23 presses the inner peripheral side of the disk substrate to move from the movable-side mold 21. Release the disk substrate.

(3) Method for Manufacturing Optical Recording Medium Next, a method for manufacturing an optical recording medium according to an embodiment of the present invention will be described. First, the movable mold 21 is moved in a direction approaching the fixed mold 11, and the fixed mold 11 and the movable mold 21 are brought into contact with each other to form the cavity 31.

  Next, the melted disk substrate material is filled into the cavity 31. As the disk substrate material, for example, a synthetic resin material such as polycarbonate can be used. The disk substrate material is heated and melted in the material supply device, and is supplied into the cavity 31 through the resin injection hole 15 as a supply path.

  Next, the disk substrate material filled in the cavity 31 is cooled and solidified, and the disk substrate material is clamped. When clamping the disk substrate material, the movable mold 21 is moved in a direction closer to the fixed mold 11. As a result, the disk substrate material filled in the cavity 31 is pressurized, and the groove and the like formed on the one main surface 32a of the stamper 32 are reliably transferred.

  Next, after the disk substrate material is sufficiently cooled and solidified, the gate cut punch 24 is moved in a direction approaching the fixed mold 11, that is, a direction protruding into the cavity 31. By moving the gate cut punch 24 in a direction protruding into the cavity 31, the runner portion and the spool portion of the solidified disk substrate material can be cut. As a result, the center hole is formed after the disk substrate material filled in the cavity 31 is solidified.

  Next, the movable mold 21 is moved away from the fixed mold 11. As a result, the solidified disk substrate is separated from the stamper 32 attached to the fixed mold 11 and one main surface is exposed to the outside. Further, when the movable mold 21 is separated from the fixed mold 11, the fixed ejector 16 is projected toward the movable mold 21. As a result, the solidified resin is discharged from the recess 17.

Next, by moving the push pin 25 in the direction of protruding into the cavity 31, the portion cut by the gate cut punch 24 is removed. Next, the movable-side ejector 23 is moved in a direction protruding into the cavity 31, thereby pressing the inner periphery of the disk substrate and releasing the disk substrate from the movable-side mold 21.
The disk substrate 1 according to one embodiment of the present invention is formed through the above steps.

  Next, the information signal portion 2 is formed on the disk substrate 1 by, for example, sputtering. Specifically, for example, when the optical recording medium as the final product is a read-only type, Al is formed on one main surface where the irregularities of the disk disk substrate 1 are formed by, for example, vacuum deposition or sputtering. A reflective layer made of Al alloy or Ag alloy is formed.

Next, the light transmission layer 3 is formed on one main surface of the disk substrate 1 where the information signal portion 2 is formed. For example, the light transmissive layer 3 is formed by attaching a light transmissive sheet to the disk substrate 1 via an adhesive layer. Alternatively, the light transmitting layer 3 may be formed by uniformly applying and curing a resin such as an ultraviolet curable resin on one main surface of the disk substrate 1 on which the information signal portion 2 is formed.
Through the above steps, an optical recording medium according to an embodiment of the present invention can be obtained.

According to one embodiment of the present invention, the following effects can be obtained.
Since the protrusion 4 is provided between the center hole 1a and the light transmission layer 3 on the information reading surface side, when the optical recording medium is used without being stored in the cartridge, the information reading surface side is at the bottom. Thus, even when placed on a table or the like, a space can be formed between the information reading surface and the table or the like. Further, even when the user loads a plurality of optical recording media, the light transmission layers 3 can be prevented from contacting each other. Therefore, it is possible to prevent adhesion of dust, dust, dust, etc. and generation of scratches. That is, the occurrence of errors during recording and / or reproduction can be reduced.

  Further, when the optical recording medium is manufactured, when the optical recording medium is stacked on a pole magazine or the like, it is not necessary to insert a spacer or the like between the optical recording media in order to prevent the light transmission layers 3 from contacting each other. Therefore, the cost required for manufacturing the optical recording medium can be kept low, and the manufacturing process of the optical recording medium can be further simplified.

  The fixed-side mold 11 and the movable-side mold 21 are brought into contact with each other to form a cavity 31, and after the resin is injected into the cavity 31, it is solidified to open the fixed-side mold 11 and the movable-side mold 21 and to disc Since the protrusions 4 formed on the inner peripheral portion of the substrate 1 protrude, the resin solidified in the concave portion 17 can be easily released from the fixed mold 11. Therefore, it is possible to manufacture an optical recording medium in which the protrusion 4 is provided on the inner peripheral portion without causing a decrease in tilt characteristics. Further, the protrusion 4 having no variation in shape and height can be provided on the optical recording medium. Furthermore, it is possible to manufacture an optical recording medium in which the protrusions 4 are provided on the inner peripheral portion without causing a reduction in operating rate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

Example First, the movable mold 21 was moved in the direction approaching the fixed mold 11, and the fixed mold 11 and the movable mold 21 were brought into contact with each other to form the cavity 31. Next, the cavity 31 was filled with molten polycarbonate.

  Next, the polycarbonate filled in the cavity 31 is cooled and solidified, and the polycarbonate is clamped. Next, after the polycarbonate was sufficiently cooled and solidified, the gate cut punch 24 was moved in the direction approaching the fixed mold 11, that is, the direction protruding into the cavity 31 to form the center hole 1 a. .

  Next, the movable mold 21 was moved away from the fixed mold 11, and the fixed ejector 16 was projected toward the movable mold 21, and the solidified resin was discharged from the recess 17. In addition, the depth of the recessed part 17 was 0.25 mm, and the protrusion width | variety of the fixed side ejector 16 was 0.25 mm.

Next, the portion cut by the gate cut punch 24 was removed by moving the extrusion pin 25 in the direction of protruding into the cavity 31. Next, the movable-side ejector 23 was moved in a direction protruding into the cavity 31, thereby pressing the inner periphery of the disk substrate 1 to release the disk substrate 1 from the movable-side mold 21.
Then, 25 disk substrates 1 were prepared by repeating the above-described steps.

25 disk substrates were obtained in the same manner as all the examples except that the fixed-side ejector 16 was not protruded by the comparative example air. In this comparative example, since there was a disk substrate in which the protrusion 4 could not be released from the concave portion 17, in reality, 25 or more disk substrates were manufactured.

  Next, with respect to the 25 disk substrates of Examples and Comparative Examples obtained as described above, the tilt was measured, and the average value and variation (standard deviation) of the tilt were calculated. Note that LM1200 (device name) manufactured by Ono Sokki Co., Ltd. was used for tilt measurement. Table 1 shows the average value, maximum value, minimum value, and variation of the tilts of the examples and comparative examples.

  Table 1 shows the following. That is, when releasing the fixed side mold 11 and the movable side mold 21, the fixed side ejector 16 is projected in the direction of the movable side mold 21, and the solidified resin is discharged from the recess 17. It can be seen that a disk substrate having good tilt characteristics can be obtained.

  Further, according to the above-described embodiments and comparative examples, the disk substrate can be easily released from the mold by causing the fixed-side ejector 16 to protrude into the movable mold 21 and discharging the solidified resin from the recess 17. I understood.

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

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

  Further, in the optical recording medium of the above-described embodiment, the width of the protrusion 4 may be increased from the tip of the protrusion toward the starting point of the protrusion. For example, as shown in FIG. 8, the protrusion 4 may be provided with a tapered portion that extends from the tip of the protrusion toward the starting point of the protrusion. The taper angle is selected to be 45 degrees, for example. In the case of such a shape, it is possible to obtain an advantage that the disk substrate 1 can be easily released from the molding die apparatus.

  Further, in the molding die device of the above-described embodiment, the width of the concave portion 17 of the molding die device may be increased from the bottom surface toward the opening end. For example, as shown in FIG. 9, a tapered portion that widens from the bottom surface side toward the opening end may be provided in the concave portion 17. The taper angle is selected to be 45 degrees, for example. In the case of such a shape, it is possible to obtain an advantage that the disk substrate 1 can be easily released from the molding die apparatus.

It is sectional drawing which shows the example of 1 structure of the optical recording medium by one Embodiment of this invention. It is a top view of the optical recording medium provided with the annular | circular shaped protrusion on the information reading surface. It is a top view of the optical recording medium provided with the spot-shaped protrusion on the information reading surface. It is a top view of the optical recording medium provided with the rib-shaped protrusion on the information reading surface. It is sectional drawing which shows one structural example of the shaping die apparatus by one Embodiment of this invention. It is an expanded sectional view which shows the example of 1 structure of the shaping die apparatus by one Embodiment of this invention. It is an expanded sectional view which shows one structural example of the stationary side ejector with which the shaping die apparatus by one Embodiment of this invention was equipped. It is sectional drawing which shows the modification of the optical recording medium by one Embodiment of this invention. It is sectional drawing which shows the modification of the shaping die apparatus by one Embodiment of this invention. It is sectional drawing which shows the structure of the conventional optical recording medium.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Fixed side metal mold | die, 12 ... Fixed mirror, 12a ... Air receiving part presser, 13 ... Stamper outer periphery holder, 14 ... Sprue bush, 15 ... Resin injection hole, 16. ..Fixed side ejector, 16a ... eject part, 16b ... air receiving part, 17 ... concave part, 18 ... space, 19 ... air passage, 20 ... air passage, 21 ...・ Moveable mold, 22 ... Moveable mirror, 23 ... Moveable ejector, 24 ... Gate cut punch, 25 ... Extrusion pin, 31 ... Cavity, 32 ... Stamper, 32a ..One main surface

Claims (6)

A step of molding a disk substrate by solidifying cavity to form corresponding to the shape of the disk substrate by closing the pair of molds to be paired direction, after injecting the resin into the cavity,
It is opened and the mold, a step protruding from the die by discharging means a protrusion formed on the inner peripheral portion of the disc substrate
With
The discharging means is
An annular discharge part protruding the protrusion,
An air receiving portion provided on the outer periphery of the discharge portion;
With
The said discharge part is a manufacturing method of the disk substrate which moves when the said air receiving part receives air . The mold is
An arrangement space in which the air receiving portion is disposed between the pair of surfaces, and the air receiving portion is disposed between the pair of surfaces;
An air supply unit that is provided at each of the pair of surfaces and supplies air into the arrangement space;
A method of manufacturing a disk substrate according to claim 1. 2. The method of manufacturing a disk substrate according to claim 1, wherein a taper portion is formed on the protrusion so that the width of the protrusion increases from the leading end side to the starting point side of the protrusion. A pair of molds facing each other,
One of the mold,
A mounting surface on which a stamper for forming an information reading surface is mounted ;
A recess for forming a protrusion on the inner periphery of the disk substrate , provided on the inner periphery of the mounting surface on which the stamper is mounted ;
A discharge means provided in the recess for protruding the resin solidified in the recess ;
With
The discharging means is
An annular discharge part protruding the protrusion,
An air receiving portion provided on the outer periphery of the discharge portion;
With
The discharge unit is a molding die device that moves when the air receiving unit receives air . The mold is
An arrangement space in which the air receiving portion is disposed between the pair of surfaces, and the air receiving portion is disposed between the pair of surfaces;
An air supply unit that is provided at each of the pair of surfaces and supplies air into the arrangement space;
The molding die apparatus of Claim 4 provided with. The molding die device according to claim 4, wherein the concave portion is formed with a tapered portion so that the width of the concave portion is widened from the bottom surface side to the opening side.

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