JP2006260650A - Optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of incomplete chucking when an optical recording medium is attached to a holding means such as a claw type chucking mechanism. <P>SOLUTION: A projecting part 2b is annularly provided on a first disk substrate 2 along an aperture provided at a center part thereof and a projecting part 5b is annularly provided on a second disk substrate 5 along an aperture provided at a center part thereof. The first and the second disk substrates 2 and 5 are stuck to each other by an adhesive layer 4 so that a protruded surface 2c of the projecting part 2b and a protruded surface 5c of the projecting part 5b abut on each other. Thereby, the tip of a claw is never inserted between the disk substrates even when the optical recording medium 1 of a sticking type is attached to the claw type chucking mechanism or the like which is provided in an electronic device such as a note book computer and a camcorder. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bonded optical recording medium in which two disk substrates are bonded together.

  In recent years, a bonded optical recording medium such as a DVD (Digital Versatile Disc) has been widely used. This bonded optical recording medium has a configuration in which the first and second disk substrates are bonded, and is mainly a DVD-ROM (Digital Versatile Disc-Read Only Memory) having φ120 mm or φ80 mm. DVD ± R (Digital Versatile Disc ± Recordable), DVD ± RW (Digital Versatile Disc ± ReWritable), DVD-DL (Digital Versatile-Double Layer), and the like.

  Conventionally, it is known that there is a gap between the first and second disk substrates in the inner peripheral portion of these various optical recording media (see, for example, Patent Document 1). If attention is paid to the gap generated in the inner peripheral portion, the bonded type optical recording medium can be divided into two types. Hereinafter, these two types of optical recording media will be sequentially described.

  FIG. 14 is a cross-sectional view showing a configuration of a first type bonded optical recording medium 301. The optical recording medium 301 is configured by bonding a first disk substrate 302 provided with an information signal portion 303 and a second disk substrate 305 via an adhesive layer 304. As the adhesive layer 304, an ultraviolet curable resin (UV curable resin) is used, and its thickness is generally set to about 30 μm to about 80 μm. Hereinafter, the surface of the first disk substrate 302 on which the information signal portion 303 is formed is referred to as a signal surface, and the surface of the second disk substrate 305 that is bonded by the adhesive layer 304 is referred to as an adhesive surface.

  As shown in FIG. 14, a recess 302 a that is recessed with respect to the signal surface is provided on the inner peripheral portion of the first disk substrate 302. A concave portion 305 a that is recessed with respect to the bonding surface is provided on the inner peripheral portion of the second disk substrate 305. The concave portion 302a and the concave portion 305a are for escaping vertical burrs generated on the end face of the opening (center hole) at the center when the first disk substrate 302 and the second disk substrate 305 are injection-molded. Since the first disk substrate 302 and the second disk substrate 305 provided with such recesses 302a and recesses 305a are bonded together with the above-described ultraviolet curable resin, a large gap is generated in the inner peripheral portion. I'm stuck.

  FIG. 15 is an enlarged cross-sectional view of the vicinity of the center of the molding die apparatus at the time of molding the disk substrate. The molding die apparatus includes a fixed side mold and a movable side mold that are arranged to face each other. The fixed die is provided with a sprue bush 401 and a stamper guide 402, and the movable die is provided with a gate cut punch 403 and an extrusion pin 404. And the convex part 401a is provided in the front-end | tip of the sprue bush 401. FIG. By providing the convex portion 401a, as shown in FIG. 15, the concave portion 302a or the concave portion 305a is formed in the inner peripheral portion of the first disk substrate 302 or the second disk substrate 305, and the center is formed at the time of injection molding. The vertical burr 302b generated on the hole end face can be released.

  FIG. 16 is a cross-sectional view showing a configuration of a second type of bonded optical recording medium. The inner peripheral portions of the first disk substrate 302 and the second disk substrate 305 are not provided with a recess for releasing a vertical burr generated on the end face of the center hole. That is, the signal surface of the first disk substrate 302 and the adhesive surface of the second disk substrate 305 have a flat shape from the inner periphery to the outer periphery. However, even if the signal surface and the adhesive surface are flat as described above, the adhesive layer used for bonding the first disk substrate 302 and the second disk substrate 305 is about 30 μm to about 80 μm as described above. Due to the thickness, a gap corresponding to the thickness of the adhesive layer is generated in the inner peripheral portion.

JP 2004-310937 A

  If there is a gap in the inner periphery of the optical recording medium 301 as described above, as shown in FIG. 17, the optical recording medium 301 is attached to a claw type chucking mechanism 501 such as a notebook computer or a camcorder. Because the tip of the nail 502 enters the bonding gap of the optical recording medium 301, the optical recording medium 301 may not be completely chucked. Hereinafter, incomplete chucking in which the nail enters the bonding gap of the optical recording medium 301 is referred to as a half chuck.

  This half chuck not only causes an Axial Error, but repeated chucking may damage the inner diameter of the disk, deform the center hole, or destroy the optical recording medium 301 itself. There is also.

  Accordingly, an object of the present invention is to provide an optical recording medium capable of preventing the occurrence of a half chuck when the optical recording medium is mounted on a holding means such as a claw type chucking mechanism.

In order to solve the above-mentioned problems, the present invention provides an optical recording medium in which an adhesive layer is bonded to a first disk substrate provided with an information signal portion on one main surface and a second disk substrate.
An optical recording medium having an opening in an inner peripheral portion and an inner peripheral surface of the opening being flush.

  In the present invention, when the optical recording medium is mounted on the holding means such as the claw type chucking mechanism, the holding means such as the chucking mechanism is not inserted between the first and second disk substrates. The opening can be passed through.

  In the present invention, the first and second disk substrates have an opening at the center, and annular protrusions are provided along the openings of the first and second disk substrates. It is preferable that the convex portions of the disk substrate are in contact with each other.

  According to the present invention, the first and second disk substrates have an opening in the center, and one of the first and second disk substrates is provided with an annular convex portion along the opening. It is preferable that a convex portion provided on one of the first and second disk substrates is fitted to the other opening.

  As described above, according to the present invention, it is possible to prevent half-chucking from occurring when the optical recording medium is mounted on a holding means such as a claw-type chucking mechanism.

  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.

  FIG. 1 is a cross-sectional view showing a structural example of an optical recording medium 1 according to the first embodiment of the present invention. FIG. 2 is an enlarged sectional view showing an example of the inner peripheral portion of the optical recording medium 1 according to the first embodiment of the present invention.

  This optical recording medium 1 has an annular shape in which an opening (hereinafter referred to as a center hole) 6 is provided at the center, and is formed on a first disk substrate 2 and one main surface of the first disk substrate 2. An information signal unit 3 provided, an adhesive layer 4 provided on the information signal unit 3, and a second disk substrate 5 provided on the adhesive layer 4 are provided. In the following, as shown in FIG. 2, the surface of the first disk substrate 2 on which the information signal portion 3 is formed is referred to as a signal surface 2 d and is bonded to the adhesive layer 4 of the second disk substrate 5. This surface is referred to as an adhesive surface 5d.

  In the optical recording medium 1 according to the first embodiment, information signals are recorded and / or reproduced by irradiating the information signal section 3 with laser light from the first disk substrate 2 side. For example, a laser beam having a wavelength in the range of 635 to 650 nm is condensed by an objective lens having a numerical aperture of about 0.6, and irradiated to the information signal unit 3 from the first disk substrate 2 side, Information signals are recorded and / or reproduced.

The first disk substrate 2 has an annular shape with an opening at the center. The second disk substrate 5 has an annular shape with an opening at the center. The thicknesses of the first disk substrate 2 and the second disk substrate 5 are selected in consideration of rigidity, for example, 0.6 mm. The inner diameter D ₁ of the first disk substrate 2 and the second disk substrate 5 is selected to be 15 mm, for example. The outer diameters of the first disk substrate 2 and the second disk substrate 5 are selected to be 120 mm, for example.

  The first disk substrate 2 is provided with an annular protrusion 2b along its inner periphery. Further, the second disk substrate 5 is provided with an annular convex portion 5b along its inner periphery. The convex portions 2 b and the convex portions 5 b are for preventing the occurrence of a bonding gap in the inner peripheral portion of the optical recording medium 1.

  The convex part 2b has, for example, a planar projecting surface 2c that projects uniformly with respect to the signal surface 2d. That is, the inner peripheral portion of the first disk substrate 2 is set at a high position with respect to the signal surface 2d. Moreover, the convex part 5b has the planar protrusion surface 5c which protruded uniformly with respect to the adhesion surface 5d, for example. That is, the inner peripheral portion of the second disk substrate 5 is set at a high position with respect to the bonding surface 5d.

  The protruding surface 2c of the protruding portion 2b and the protruding surface 5c of the protruding portion 5b are brought into contact with each other when the first disk substrate 2 and the second disk substrate 5 are bonded together, and the inner periphery of the first disk substrate 2 The surface 2a and the inner peripheral surface 5a of the second disk substrate 5 are connected flush with each other. By doing in this way, it can prevent that a clearance gap generate | occur | produces in an inner peripheral part. Therefore, when the optical recording medium 1 is chucked to a claw type chucking mechanism or the like, it is possible to prevent the chuck claw from entering between the first disk substrate 2 and the second disk substrate 5. Further, it is possible to prevent dust and moisture from entering from the inner peripheral portion and improve the reliability of the optical recording medium 1.

  In addition, the shape of the convex part 2b and the convex part 5b contacts the convex part 2b and the convex part 5b, and the inner peripheral surface 2a of the first disk substrate 2 and the inner peripheral surface 5a of the second disk substrate 5 are in contact with each other. The shape is not limited to the above example, as long as it can be connected to the same surface. For example, the shape of the protruding surface 2c and the protruding surface 5c can be a curved surface, a stepped shape, or the like.

  For example, when the first disc substrate 2 and the second disc substrate 5 are injection-molded, the convex portion 2b and the convex portion 5b are integrally formed with the first disc substrate 2 and the second disc substrate 5, respectively. . In the first embodiment, a case where the convex portions 2b and the convex portions 5b are integrally formed on the inner peripheral portions of the first disk substrate 2 and the second disk substrate 5 will be described. The forming method of 5b is not limited to integral molding. For example, the first disk substrate 2 and the second disk substrate 5 having a flat shape from the inner periphery to the outer periphery are injection-molded, and the inner periphery of the first disk substrate 2 and the second disk substrate 5 is injected. Then, an annular member produced in a separate process may be bonded.

The heights of the convex portions 2b and the convex portions 5b are selected in consideration of the thickness of the adhesive layer 4. For example, the total height of the convex portions 2b and the convex portions 5b is substantially equal to the thickness of the adhesive layer 4. Specifically, for example, 10 to 60 μm, preferably 20 to 40 μm is selected. Outer diameter D ₃ of the projections 2b and the convex portion 5b is chosen equal to or smaller than the inner diameter D ₅ of the information signal portion formed area 3a, selected for example 44mm or less.

On one main surface of the first disk substrate 2, an information signal portion forming area 3a for forming the information signal portion 3 is set. The information signal portion forming area 3a has an annular shape centering on an opening provided in the central portion. The information signal portion forming area 3a is provided with an uneven portion for guiding an optical spot when recording and / or reproducing information signals. Examples of the shape of the uneven portion include various shapes such as a spiral shape, a concentric circle shape, and a pit row. In addition, a clamping area is set on the inner periphery of the optical recording medium 1. This clamping area has an annular shape centering on an opening provided in the center. The inner diameter D ₂ of the clamping area is set to, for example, 22 mm. The outer diameter D ₄ of the clamping area is set to, for example, 33 mm.

Here, the thickness of the inner peripheral portion of the optical recording medium 1 will be described with reference to FIG. The thickness of the optical recording medium 1 in the region of the inner diameter D _{1 to} φ16 mm is selected from 0.9 mm to 1.4 mm, for example. The thickness of the optical recording medium 1 at φ16 mm to the inner diameter D ₂ of the clamping area is selected from 0.9 mm to 1.5 mm, for example. The thickness of the optical recording medium 1 from the inner diameter D _{2 of the} clamping area to the outer diameter D ₄ of the clamping area is selected in the range of 1.1 mm to 1.4 mm, for example. The thickness of the optical recording medium 1 in the range of the outer diameter D _{4 to} φ40 mm of the clamping area is selected from, for example, 0.94 mm to 2.0 mm. The thickness of the optical recording medium 1 in the region of φ40 mm to the inner diameter D ₅ of the information signal portion forming area 3a is selected from 1.14 mm to 1.5 mm, for example.

  As a material of the first disk substrate 2 and the second disk substrate 5, 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 first disk substrate 2 and the second disk substrate 5. As a molding method of the first disk substrate 2 and the second disk substrate 5, for example, an injection molding method (injection method) or a photopolymer using an ultraviolet curable resin (2P method: Photo Polymerization) can be used. Other than this, any method can be used as long as it has a desired shape and optically sufficient substrate surface smoothness.

  The information signal unit 3 is configured to be able to record and / or reproduce information signals. The configuration of the information signal unit 3 differs depending on whether the optical recording medium 1 is a read-only type, a write-once type, or a rewritable type. When the optical recording medium 1 is a read-only type, the information signal unit 3 includes, for example, a reflective film, and examples of the material of the reflective film include metal elements, metalloid elements, compounds or mixtures thereof. More specifically, for example, simple substances such as Al, Ag, Au, Ni, Cr, Ti, Pd, Co, Si, Ta, W, Mo, and Ge, or alloys containing these simple substances as main components can be mentioned. It is done. 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.

  When the optical recording medium 1 is a write-once type, the information signal unit 3 is a laminated film in which, for example, an organic dye film and a reflective film are sequentially laminated on the first disk substrate 2. When the optical recording medium 1 is a rewritable type, the information signal unit 3 sequentially stacks, for example, a lower dielectric layer, a phase change recording film, an upper dielectric layer, and a reflective film on the first disk substrate 2. This is a laminated film.

  The adhesive layer 4 is for protecting the information signal portion 3 and bonding the first disk substrate 2 and the second disk substrate 5 together. The adhesive layer 4 is made of, for example, an ultraviolet curable resin. The thickness of the adhesive layer 4 is set in the range of about 30 μm to about 80 μm, for example.

  FIG. 3 is a cross-sectional view showing a configuration example of the molding die device 11 according to the first embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view showing a configuration example of the molding die device 11 according to the first embodiment of the present invention.

  Hereinafter, the configuration of the molding die apparatus 11 according to the first embodiment will be described with reference to FIGS. 3 and 4. As shown in FIG. 3, the molding die device 11 includes a fixed mold 12 and a movable mold 13, and these fixed mold 12 and the movable mold 13 are brought into contact with each other. Thus, the cavity 14 which is a molding space is formed. In this molding die apparatus 11, the melted disk substrate material is filled into the cavity 14 to mold the disk substrate.

  The fixed mold 12 includes a fixed mirror 21 on the surface facing the movable mold 13, and a stamper 22 is attached to the surface on which the cavity 14 is formed. The stamper 22 has an annular shape with an opening at the center, and the main surface 22a of the stamper 22 is formed with irregularities corresponding to, for example, lands and grooves. The stamper 22 is attached to the fixed mold 12 so that the one principal surface 22 a side faces the movable mold 13.

  Further, a sprue bush 23 is provided at a substantially central portion of the fixed side mold 12. A resin injection hole 24 is provided at the center of the sprue bush 23. The resin injection hole 24 is connected to a material supply device (not shown). The molten disk substrate material is supplied from the material supply device into the cavity 14 through the resin injection hole 24.

  The upper surface 23 a of the sprue bush 23 is set at a position recessed with respect to one main surface of the stamper 22. The width of the recess is selected according to the height of the convex portion 2b provided on the inner peripheral portion of the first disk substrate 2, and is selected, for example, from 10 to 60 μm, preferably from 20 to 40 μm.

  A stamper guide 25 is provided between the sprue bush 23 and the fixed mirror 21. The stamper guide 25 is for guiding the inner periphery of the stamper 22 when the stamper 22 is mounted on the solid mirror 21.

  On the other hand, the movable mold 13 is disposed so as to face the fixed mold 12, and can be moved close to and away from the fixed mold 12 by a guide pole 15 provided with a ball bearing 16 at the tip. Has been. The movable mold 13 includes a movable mirror 31 on the surface facing the fixed mold 12. The movable die 13 has a gate cut punch 32 that cuts the central portion of the disk substrate solidified in the cavity 14 and a push pin 33 that pushes out the central portion cut by the gate cut punch 32 at the substantially central portion thereof. And a movable ejector 34 for releasing the disk substrate from the movable mold 13.

  The gate cut punch 32 cuts the runner portion of the disc substrate material supplied from the sprue bush 23 into the cavity 14 and solidified, and has an outer dimension substantially the same as the center hole 6 of the optical recording medium 1. It has a diameter. The gate cut punch 32 can be moved in a direction protruding into the cavity 14 by guide means and drive means (not shown).

  The clearance between the gate cut punch 32 and the sprue bush 23 is set to about 5 μm on one side when concentric. By setting the clearance in this way, it is possible to avoid the occurrence of vertical burrs between the gate cut punch 32 and the sprue bush 23 during injection molding. Therefore, unlike the prior art, it is not necessary to provide a convex portion for releasing burrs on the upper surface of the sprue bush. Conventionally, the clearance between the gate cut punch 32 and the sprue bush 23 is set to about 10 μm on one side when concentric. Centering of the gate cut punch 32 and the sprue bush 23 is performed by the guide post 15 including the ball bearing 16 described above.

  The extrusion pin 33 has a rod-like shape and is arranged at the center of the gate cut punch 32. The push pin 33 can be moved in a direction protruding into the cavity 14 by a guide means or a drive means (not shown), and removes the portion cut by the gate cut punch 32 described above. Therefore, after the disk substrate material filled in the cavity 14 is solidified, the extrusion pin 33 is pushed out, whereby the runner portion and the sprue, that is, the disk substrate material accumulated in the supply portion of the runner portion and the sprue bush 23 are collected. And can be removed.

  The movable ejector 34 is configured to have a cylindrical shape having an inner diameter substantially the same as the outer diameter of the gate cut punch 32, and is disposed so as to surround the gate cut punch 32. This movable-side ejector 34 can be moved in a direction protruding into the cavity 14 by a guide means and a drive means (not shown). Therefore, after the disk substrate material is filled in the cavity 14 and the center hole of the disk substrate is formed as described above, the movable side ejector 34 presses the inner peripheral side of the disk substrate to move from the movable side mold 13. Release the disk substrate.

  In addition, it is preferable to perform DLC (Diamond Like Carbon) processing, chromium processing, or organic thin film processing, such as a fluororesin, on the surface of the sprue bush 23 and the stamper guide 25. By performing such processing, it is possible to improve the releasability of the convex portions 2b and the convex portions 5b. Therefore, even when the shapes of the convex portions 2b and the convex portions 5b are increased, it is possible to prevent the occurrence of polarization anomalies such as a substrate remaining in the mold and a cloud (release pattern). Further, the surface may be modified by applying a texture treatment for forming a large number of minute protrusions or a surface modification treatment by embossing to improve the releasability of the convex portions 2b and the convex portions 5b.

  Next, an example of a manufacturing method for the optical recording medium according to the first embodiment of the present invention will be described.

(First disk substrate forming step)
First, the movable mold 13 is moved in the direction approaching the fixed mold 12, and the fixed mold 12 and the movable mold 13 are brought into contact with each other to form the cavity 14. Next, the melted disk substrate material is filled into the cavity 14. 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 14 through the resin injection hole 24 as a supply path.

  Next, the disk substrate material filled in the cavity 14 is cooled and solidified, and the disk substrate material is clamped. When clamping the disk substrate material, the movable side mold 13 is moved in a direction closer to the fixed side mold 12. As a result, the disk substrate material filled in the cavity 14 is pressurized, and the unevenness provided on the main surface 22a of the stamper 22 is reliably transferred.

  Next, after the disk substrate material is sufficiently cooled and solidified, the gate cut punch 32 is moved in the direction approaching the fixed mold 12, that is, the direction protruding into the cavity 14. By moving the gate cut punch 32 in a direction protruding into the cavity 14, the runner portion and the sprue portion of the solidified disk substrate material can be cut. Thereby, after the disk substrate material filled in the cavity 14 is solidified, an opening is formed at the center.

  Next, the movable mold 13 is moved away from the fixed mold 12. As a result, the solidified disk substrate is separated from the stamper 22 attached to the fixed mold 12 and one main surface is exposed to the outside.

  Next, the extrusion pin 33 is moved in the direction protruding into the cavity 14 to remove the portion cut by the gate cut punch 32 described above. Next, the movable-side ejector 34 is moved in a direction protruding into the cavity 14, thereby pressing the inner periphery of the disk substrate and releasing the disk substrate from the movable-side mold 13. Through the above steps, the first disk substrate 2 according to the embodiment of the present invention is formed.

(Information signal part formation process)
Next, the information signal portion 3 is formed on the first disk substrate 2 by, for example, sputtering. Specifically, for example, when the optical recording medium 1 as a final product is a read-only type, for example, a vacuum deposition method, a sputtering method, etc. Thus, a reflective film made of Al, Al alloy, Ag alloy or the like is formed.

(Second disk substrate molding process)
Next, the second disk substrate 5 is formed by, for example, an injection molding method. The second disk substrate 5 can be molded, for example, by attaching a stamper 22 having a planar molding surface to the fixed mirror 21 of the molding die device 11 described above. Note that the molding of the second disk substrate 5 may be performed in parallel with the molding of the first disk substrate 2.

(Lamination process)
Next, an ultraviolet curable resin is uniformly applied on the information signal portion 3 by, for example, a spin coating method. In this case, so as to applying a UV curable resin to the outer position than the outer diameter D ₃ of the convex portion 2b. Then, the second disk substrate 5 is placed on the first disk substrate 2 so that the protruding surface 2c of the convex portion 2b and the protruding surface 5c of the convex portion 5b are brought into contact with each other. And the ultraviolet-ray is irradiated by adjusting the thickness of the ultraviolet curable resin as appropriate. As a result, the ultraviolet curable resin is cured, and the first disk substrate 2 and the second disk substrate 5 are bonded together to form the adhesive layer 4. Through the above steps, the target optical recording medium 1 according to the first embodiment can be obtained.

According to the first embodiment of the present invention, the following effects can be obtained.
The first disk substrate 2 is provided with a convex portion 2b in an annular shape along an opening provided in the central portion thereof, and the second disk substrate 5 is provided in an annular shape along an opening provided in the central portion thereof. Protrusions 5b are provided. Then, the first disk substrate 2 and the second disk substrate 5 are bonded together by the adhesive layer 4 so that the protruding surface 2c of the convex portion 2b and the protruding surface 5c of the convex portion 5b are in contact with each other. Thereby, even when the bonded optical recording medium 1 is attached to the nail type chucking mechanism provided in an electronic device such as a notebook computer or a camcorder, the tip of the nail enters between the disk substrates. There is nothing. Therefore, it is possible to eliminate the half chuck that occurs when the optical recording medium 1 is mounted on the claw type chucking mechanism. In addition, it is possible to provide an optical recording medium 1 free from Axial Error or the like and excellent in recording / reproducing characteristics. Furthermore, it is possible to provide an optical recording medium 1 that can withstand multiple attachments and detachments and has excellent durability. Furthermore, since dust and moisture do not enter the optical recording medium 1 from between the inner peripheral substrates, the optical recording medium 1 having excellent reliability can be provided.

  Next explained is the second embodiment of the invention. In the first embodiment described above, the case where both the first and second disk substrates have annular convex portions on the inner peripheral portion has been described. However, in the second embodiment, only the second disk substrate is provided. The case where has a convex part in an inner peripheral part is demonstrated.

  FIG. 5 is a sectional view showing an example of the configuration of the optical recording medium 101 according to the second embodiment of the present invention. FIG. 6 is an enlarged sectional view showing an example of the inner peripheral portion of the optical recording medium 101 according to the second embodiment of the present invention.

  The first disk substrate 102 has an annular shape with an opening at the center. The second disk substrate 103 has an annular shape with an opening at the center. The second disk substrate 103 is provided with an annular convex portion 103b along its inner periphery. The first disk substrate 102 and the third disk substrate 103 are bonded together so that the convex portion 103 b is fitted to the opening of the first disk substrate 102. By doing so, the joint between the first disk substrate 102 and the second disk substrate 103 can be eliminated from the inner peripheral surface 103 a of the optical recording medium 101. Therefore, the inner peripheral surface 103a of the optical recording medium 101 can be made flush.

The protrusion 103b has a protruding surface 103c that protrudes substantially uniformly with respect to the bonding surface 103d. Therefore, the inner periphery of the second disk substrate 103 is set at a position higher than the bonding surface 103d as shown in FIG. Outer diameter D ₁₁ of the convex portion 103b is, for example information signal portion formed area 3a inner diameter D ₅ is chosen in the following, are selected, for example 44mm or less. The inner diameter of the first disc substrate 102 is chosen substantially equal to the outer diameter D ₁₁ of the convex portion 103b, it is selected to be, for example, 44 mm.

Here, the thickness of the inner peripheral portion of the optical recording medium 101 will be described with reference to FIG. The thickness of the optical recording medium 101 in the region of the inner diameter D _{1 to} φ16 mm is selected from 0.9 mm to 1.4 mm, for example. The thickness of the optical recording medium 101 at φ16 mm to the inner diameter D ₂ of the clamping area is selected from 0.9 mm to 1.5 mm, for example. The thickness of the optical recording medium 101 from the inner diameter D _{2 of the} clamping area to the outer diameter D ₄ of the clamping area is selected in the range of 1.1 mm to 1.4 mm, for example. The thickness of the optical recording medium 101 in the range of the outer diameter D _{4 to} φ40 mm of the clamping area is selected from, for example, 0.94 mm to 2.0 mm. The thickness of the optical recording medium 101 in the region of φ40 mm to the inner diameter D ₅ of the information signal portion formation area 3a is selected from 1.14 mm to 1.5 mm, for example. In addition, the shape of the protrusion surface 103c of the convex part 103b is prescribed | regulated based on the above-mentioned numerical range, for example. Since other than this is the same as that of the first embodiment described above, the description thereof is omitted.

  In the second embodiment of the present invention, the same effect as in the first embodiment described above can be obtained.

  Next explained is the third embodiment of the invention. In the first embodiment described above, a case has been described in which both the first and second disk substrates have annular convex portions on the inner peripheral portion. In the third embodiment, only the first disk substrate is provided. The case where has a convex part in an inner peripheral part is demonstrated.

  FIG. 7 is a sectional view showing an example of the configuration of the optical recording medium 201 according to the third embodiment of the present invention. FIG. 8 is an enlarged cross-sectional view showing an example of the inner periphery of the optical recording medium 201 according to the third embodiment of the present invention.

  The first disk substrate 202 has an annular shape with an opening at the center. The second disk substrate 203 has an annular shape with an opening at the center. The first disk substrate 202 is provided with an annular convex portion 202b along its inner periphery. The first disk substrate 202 and the third disk substrate 203 are bonded together so that the convex portion 202 b is fitted to the opening of the second disk substrate 203. By doing so, the joint between the first disk substrate 202 and the second disk substrate 203 can be eliminated from the inner peripheral surface 202 a of the optical recording medium 201. Therefore, the inner peripheral surface 202a of the optical recording medium 201 can be made flush.

The convex portion 202b has a protruding surface 202c that protrudes substantially uniformly with respect to the signal surface 202d. Therefore, the inner periphery of the first disk substrate 202 is set at a position higher than the signal surface 202d as shown in FIG. Outer diameter D ₂₁ of the convex portion 202b is, for example information signal portion formed area 3a inner diameter D ₅ is chosen in the following, are selected, for example 44mm or less. The inner diameter of the second disk substrate 203 is selected to be substantially the same as the outer diameter D ₂₁ of the convex portion 202b, for example, 44 mm.

Here, the thickness of the inner peripheral portion of the optical recording medium 201 will be described with reference to FIG. The thickness of the optical recording medium 201 in the region of the inner diameter D _{1 to} φ16 mm is selected from 0.9 mm to 1.4 mm, for example. The thickness of the optical recording medium 201 at φ16 mm to the inner diameter D ₂ of the clamping area is selected from 0.9 mm to 1.5 mm, for example. The thickness of the optical recording medium 201 from the inner diameter D _{2 of the} clamping area to the outer diameter D ₄ of the clamping area is selected in the range of 1.1 mm to 1.4 mm, for example. The thickness of the optical recording medium 201 in the range of the outer diameter D _{4 to} φ40 mm of the clamping area is selected from, for example, 0.94 mm to 2.0 mm. The thickness of the optical recording medium 201 in the region of φ40 mm to the inner diameter D ₅ of the information signal portion forming area 3a is selected from 1.14 mm to 1.5 mm, for example. In addition, the shape of the protrusion surface 202c of the convex part 202b is prescribed | regulated based on the above-mentioned numerical range, for example. Since other than this is the same as that of the first embodiment described above, the description thereof is omitted.

  In the third embodiment of the present invention, the same effect as in the first embodiment described above can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.
Embodiment First, the upper surface 23a of the sprue bush 23 of the molding die apparatus 11 is shaved to make the upper surface 23a of the sprue bush 23 flat, and the upper surface 23a is recessed by 40 μm with respect to the one main surface 22a of the stamper 22. It was adjusted. Moreover, the clearance between the sprue bush 23 and the gate cut punch 32 was set to 5 μm on one side when concentric.

  Next, the first disk substrate 2 having the convex portion 2b having a height of 40 μm on the inner peripheral portion was molded using the molding die device 11 adjusted as described above. The projecting surface 2c has a planar shape parallel to the signal surface 2d. Next, a recording film and a reflective film as the information signal portion 3 were formed on the first disk substrate 2 by sputtering.

  Next, in the same manner as the first disk substrate 2 was molded, a second disk substrate 5 having a convex portion 5b with a height of 40 μm on the inner peripheral portion was obtained. The projecting surface 5c has a planar shape parallel to the bonding surface 5d.

  Next, an ultraviolet curable resin was uniformly applied on the first disk substrate 2 by spin coating. Then, the second disk substrate 5 is placed on the first disk substrate 2 so that the projecting surface 2c of the projecting portion 2b and the projecting surface 5c of the projecting portion 5b are brought into contact with each other. The thickness was appropriately adjusted and irradiation with ultraviolet rays was performed. The target optical recording medium 1 was obtained through the above steps.

Comparative Example The optical recording medium is the same as the above-described embodiment except that the first disk substrate and the second disk substrate having a flat shape from the inner periphery to the outer periphery are used. Got.

(Evaluation of inner cross-section)
Next, the inner peripheral section of the optical recording media of Examples and Comparative Examples obtained as described above was evaluated. FIG. 9 shows a cross section of the inner periphery of the optical recording medium 1 of the comparative example. FIG. 10 shows a cross section of the inner periphery of the optical recording medium of the example. Comparing FIG. 9 and FIG. 10, in the comparative example, a gap is generated between the substrates in the inner peripheral portion, whereas in the embodiment, no gap is generated between the substrates in the inner peripheral portion. I understand that.

(Evaluation of chucking state)
Next, with respect to the optical recording media of Examples and Comparative Examples obtained as described above, a plurality of inspectors conducted the following tests, respectively, to evaluate the chucking state. That is, the mounting operation of slowly chucking the optical recording medium to the nail type chucking mechanism provided in the video camera device is repeated 100 times, and the optical recording medium is not completely chucked by the nail type chucking mechanism. The number of stops was recorded. Based on the recorded data, the occurrence rate of the half chuck was calculated.

  FIG. 11 shows a claw type chucking mechanism 41 used for evaluating the chucking state. The claw type chucking mechanism 41 is configured to place the optical recording medium on the placing portion 43 so that the claw 42 passes through the inner peripheral portion of the optical recording medium.

  From the above calculation results, it was found that the occurrence rate of the half chuck was 5.3% in the comparative example, whereas the occurrence rate of the half chuck could be suppressed to 0% in the example.

  Although the first to third embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described first to third embodiments, and is based on the technical idea of the present invention. Various variations based on this are possible.

  For example, the numerical values given in the first to third embodiments are merely examples, and different numerical values may be used as necessary.

  In the first to third embodiments described above, the optical recording medium having one information signal portion has been described. However, the number of information signal portions is not limited to this, and the number of information signal portions is two or more. An information signal unit may be provided.

  In the first embodiment described above, a convex portion is provided on one of the first and second disk substrates, and the convex portion provided on one of the first and second disk substrates is replaced with the inner peripheral portion of the other. The inner peripheral surface of the optical recording medium may be flush with the surface.

  FIG. 12 is a cross-sectional view showing a configuration example of the optical recording medium 1 of the first modification. On the signal surface of the first disk substrate 2, an annular convex portion 2b is provided along the inner periphery thereof. The protruding surface of the convex portion 2b has, for example, a planar shape parallel to the signal surface. The bonding surface of the second disk substrate 5 has a flat shape from the inner periphery to the outer periphery. The inner diameters of the first disk substrate 2 and the second disk substrate 5 are set to be the same.

  When the first disk substrate 2 and the second disk substrate 5 are bonded together, the protruding surface of the convex portion 2b provided on the first disk substrate 2 and the inner peripheral portion of the second disk substrate 5 are The inner peripheral surface 2a of the first disk substrate 2 and the inner peripheral surface 5a of the second disk substrate 5 are connected flush with each other.

  FIG. 13 is a cross-sectional view illustrating a configuration example of the optical recording medium 1 according to the second modification. On the bonding surface of the second disk substrate 5, an annular convex portion 5b is provided along its inner periphery. The protruding surface of the convex part 5b has, for example, a planar shape parallel to the adhesive surface. The signal surface of the first disk substrate 2 has a flat shape from the inner periphery to the outer periphery. The inner diameters of the first disk substrate 2 and the second disk substrate 5 are set to be the same.

  When the first disk substrate 2 and the second disk substrate 5 are bonded together, the protruding surface of the convex portion 5b provided on the second disk substrate 5 and the inner peripheral portion of the first disk substrate 2 are The inner peripheral surface 2a of the first disk substrate 2 and the inner peripheral surface 5a of the second disk substrate 5 are connected flush with each other.

It is sectional drawing which shows one structural example of the optical recording medium by 1st Embodiment of this invention. It is an expanded sectional view showing an example of the inner circumference part of the optical recording medium by a 1st embodiment of this invention. It is sectional drawing which shows the example of 1 structure of the shaping die apparatus by 1st Embodiment of this invention. It is an expanded sectional view showing an example of 1 composition of a molding die device by a 1st embodiment of this invention. It is sectional drawing which shows the example of 1 structure of the optical recording medium by the 2nd Embodiment of this invention. It is an expanded sectional view which shows an example of the inner peripheral part of the optical recording medium by 2nd Embodiment of this invention. It is sectional drawing which shows the example of 1 structure of the optical recording medium by the 3rd Embodiment of this invention. It is an expanded sectional view which shows an example of the inner peripheral part of the optical recording medium by 3rd Embodiment of this invention. It is sectional drawing of the inner peripheral part of the optical recording medium of a comparative example. It is sectional drawing of the inner peripheral part of the optical recording medium of an Example. It is a schematic diagram which shows the nail | claw type chucking mechanism used for evaluation of a chucking state. It is sectional drawing which shows the example of 1 structure of the optical recording medium of a 1st modification. It is sectional drawing which shows the example of 1 structure of the optical recording medium of a 2nd modification. It is sectional drawing which shows the structure of the 1st type bonding type optical recording medium. It is an expanded sectional view of the molding die apparatus at the time of disk substrate fabrication. It is sectional drawing which shows the structure of the 2nd type bonding type optical recording medium. It is sectional drawing of the optical recording medium at the time of mounting | wearing with a chucking mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical recording medium 2 1st disc substrate 3 Information signal part 4 Adhesive layer 5 2nd disc substrate 2a, 5a Inner peripheral surface 2b, 5b Convex part 6 Center hole

Claims (3)

In an optical recording medium in which a first disk substrate provided with an information signal portion on one main surface and a second disk substrate are bonded together by an adhesive layer,
An optical recording medium having an opening in an inner peripheral portion, and an inner peripheral surface of the opening being flush. The first and second disk substrates have an opening in the center,
An annular protrusion is provided along the openings of the first and second disk substrates,
2. The optical recording medium according to claim 1, wherein the convex portions of the first and second disk substrates are in contact with each other. The first and second disk substrates have an opening in the center,
One of the first and second disk substrates is provided with an annular convex portion along the opening,
2. The optical recording medium according to claim 1, wherein a convex portion provided on one of the first and second disk substrates is fitted to the other opening.

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