JP2007073124A - Method and device for manufacturing optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for manufacturing an optical recording medium capable of forming a cover layer with a uniform thickness so as to prevent the generation of burrs or peeling. <P>SOLUTION: A radiation curable resin material 18 is supplied annularly around a center hole 12 on a substrate 14 in a flowing state, a translucent circular covering member 20 having a center hole 22A, formed into a circular plate shape, and having an outer diameter smaller than the inner diameter of a recording area Ar is moved and mounted onto the resin material 18, the substrate 14 and the circular covering member 20 are rotated to make the resin material 18 flow outside in the radial direction by a centrifugal force to spread on the substrate 14, and a radiation ray is irradiated to the substrate 14 to harden the resin material 18, and then the circular covering member 20 is peeled off. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for manufacturing an optical recording medium in which a cover layer thinner than a substrate is formed on a substrate and a center hole is formed.

  As information recording media, optical recording media such as CD (Compact Disc) and DVD (Digital Versatile Disc) are rapidly spreading. An optical recording medium is generally standardized to have an outer diameter of 120 mm and a thickness of 1.2 mm. However, DVD uses laser light having a shorter wavelength than CD as irradiation light, and also sets the numerical aperture of the lens of irradiation light. By making it larger than a CD, it is possible to record / reproduce information having a higher density and a higher capacity than a CD.

  Note that the shorter the wavelength of the irradiating light and the larger the numerical aperture of the lens, the more likely the information recording / reproducing accuracy tends to decrease due to the tilt and warp of the disc. By setting the thickness to .6 mm, a margin for tilting and warping of the disk is ensured, and information recording / reproducing accuracy is maintained.

  In recent years, in order to realize higher density and higher capacity information recording, optical recording with a shorter cover wavelength and a correspondingly thinner lens is provided. The media is spreading.

  In order to unify the specifications, an optical recording medium using a blue-violet laser beam having a wavelength of about 405 nm as an irradiation light, a numerical aperture of 0.85, and a cover layer thickness of about 100 μm is becoming widespread. .

  Among these optical recording media, the single-sided single-layer recording type has a substrate thickness of 1.1 mm so that the overall thickness is 1.2 mm. The substrate is generally formed by injection molding excellent in mass productivity. Specifically, a resin such as polycarbonate is injected between a pair of molds, cooled and kept at a predetermined temperature, and formed into a disk shape. After the injection molding, the central portion is punched to form a central hole having a diameter of 15 mm, for example.

  The cover layer is formed on the substrate by a spin coat method or the like. Specifically, first, a radiation curable resin material that has transparency and is cured by being irradiated with radiation such as ultraviolet curable and electron beam curable, in a fluidized state. Feed around the ring. There is also known a technique in which a central hole of a substrate is closed with a cap or the like and a resin material is supplied onto the cap or the like (see, for example, Patent Documents 1, 2, 3, and 4). A technique is also known in which a substrate is formed into a disk shape without a central hole, and a resin material is supplied near the center of the substrate.

  Next, the substrate is rotated, and the supplied resin material is caused to flow radially outward by a centrifugal force so as to spread over the entire surface of the substrate. After spreading, the substrate is irradiated with radiation such as ultraviolet rays or electron beams to cure the resin material. Thereby, a cover layer is formed and the optical recording medium is completed. In the case of double-sided single-layer recording, the thickness of the substrate is 1.0 mm, and a cover layer of 100 μm may be formed on each side of the substrate. When two or more recording layers are provided on one side or both sides, a cover layer thinner than 100 μm is formed. In the case where the cover layer is formed on the substrate having no central hole, the central hole is formed by punching the central portion of the substrate and the cover layer after the cover layer is formed.

Japanese Patent Laid-Open No. 11-195250 JP-A-11-195251 Japanese Patent Laid-Open No. 11-213459 Japanese Patent Application Laid-Open No. 11-66647

  However, if the resin material is supplied in an annular shape around the center hole of the substrate and the substrate is rotated, the thickness of the spread resin is likely to be non-uniform, making it difficult to record and reproduce high-density information. is there. Specifically, the spread resin tends to be thicker toward the outer side in the radial direction.

  The reason why the thickness is not uniform is not necessarily clear, but it is generally considered as follows. When the resin material is supplied to the periphery of the central hole, a centrifugal force immediately acts on the resin material due to the rotation of the substrate and flows outward in the radial direction. Since the centrifugal force is stronger toward the outside in the radial direction, the flow rate of the resin material tends to vary in the radial direction. In addition, since it is difficult to supply the resin material uniformly and uniformly around the entire circumference, the flow amount of the resin material may vary in the circumferential direction. On the other hand, even if the flow amount varies, it is difficult to control the flow amount. Thus, it is considered that the thickness of the cover layer becomes non-uniform because the resin material is spread with the flow amount varied.

  On the other hand, if the center hole of the substrate is closed with a cap or the like and a resin material is supplied onto the cap or the like, the resin material can be supplied to the central portion of the substrate, and a centrifugal force is immediately applied to the supplied resin material. Can be avoided. In this case, the central part of the substrate acts as a reservoir for the resin material, and the flow rate of the resin material on the substrate is buffered and stabilized, so the resin material can be spread with a uniform thickness. However, it is necessary to wash the cap or the like to which the resin material is adhered every time, and there is a problem that the production equipment becomes complicated due to the washing equipment and the production efficiency is low.

  In addition, when supplying the resin material near the center of the substrate without the center hole, the spread resin is cured, and then the cover layer and the substrate are punched out with a circular tool or the like to form the center hole. Since the cover layer is an extremely thin layer having a thickness of 100 μm or less, when punching with a circular tool or the like, burrs may occur on the inner peripheral portion of the cover layer, or the inner peripheral portion of the cover layer may peel off.

  Further, since the optical recording medium is held by the recording / reproducing apparatus or the like in the central hole, the inner peripheral portion of the cover layer may be peeled off by being repeatedly detached from the recording / reproducing apparatus.

  The present invention has been made in view of the above problems, and provides an optical recording medium manufacturing method and manufacturing apparatus capable of forming a cover layer with a uniform thickness so that burrs and peeling do not occur. Objective.

  The present invention supplies a radiation curable resin material on a substrate in an annular shape around a central hole in a flowing state, and has a disc shape having a central hole and has a translucency with an outer diameter smaller than the inner diameter of a recording area. The circular covering member is transferred onto the annular resin material, the substrate and the circular covering member are rotated, the resin material is caused to flow radially outward by centrifugal force and spread on the substrate, and the substrate is irradiated with radiation. Then, the above-mentioned object is achieved by curing the resin material and peeling off the circular covering member.

  In this way, by rotating the substrate after transferring the circular covering member onto the annular resin material, the flow of the resin material is circularly coated even if the resin material is annularly supplied around the central hole of the substrate. Since it can be controlled by the member, the resin material can be spread over the entire surface of the substrate with a uniform thickness.

  That is, the above object can be achieved by the following invention.

  (1) A resin material supply step of supplying a radiation curable resin material having translucency on a substrate having a disc shape having a center hole and disposed substantially horizontally in a ring shape around the center hole in a fluid state A circular covering member transfer step of transferring a circular covering member having a disc shape having a central hole and having a light transmitting property whose outer diameter is smaller than the inner diameter of the recording area onto the annular resin material, and the substrate And rotating the circular covering member to cause the resin material to flow radially outward by centrifugal force and spreading the resin material on the substrate, and curing the resin material by irradiating the substrate with radiation. A method for producing an optical recording medium, comprising: a radiation irradiation step for causing a circular covering member to peel off the circular covering member from the resin material.

  (2) The method of manufacturing an optical recording medium according to (1), wherein the circular covering member is pressed toward the substrate in at least one of the circular covering member transfer step and the spreading step.

  (3) The method of manufacturing an optical recording medium according to (1) or (2), wherein, in the radiation irradiating step, radiation is applied to the vicinity of the outer periphery of the circular covering member while rotating the substrate.

  (4) The method for producing an optical recording medium according to any one of (1) to (3), wherein a circular covering member having at least a contact surface with the resin material is water-repellent as the circular covering member.

  (5) In any one of (1) to (4), a circular covering member having a tapered outer peripheral side surface is used as the circular covering member, and the outer periphery is moved away from the substrate in the circular covering member transfer step. A method of manufacturing an optical recording medium, wherein the circular covering member is transferred onto the resin material in a posture in which a side surface has a diameter expanded.

  (6) In any one of (1) to (5), after the circular covering member peeling step, the step portion pressurizing the step portion corresponding to the outer periphery of the circular covering member in the resin material in the thickness direction. A method of manufacturing an optical recording medium, comprising a step.

  (7) In any one of (1) to (5), a step removing step for removing a step corresponding to the outer periphery of the circular covering member in the resin material is provided after the circular covering member peeling step. A method of manufacturing an optical recording medium.

  (8) A rotary table for installing a disk-shaped substrate having a center hole substantially horizontally, and a radiation curable resin material having translucency on the substrate in a fluid state around the center hole. A resin material supply device for supplying an annular shape and a circular covering member having a disc shape having a central hole and having an outer diameter smaller than the inner diameter of the recording area are transferred onto the annular resin material. A circular covering member transfer device for irradiating the substrate with radiation and curing the resin material spread on the substrate, and peeling the circular covering member from the resin material An apparatus for manufacturing an optical recording medium, comprising:

  (9) In (8), the circular covering member transfer device can pressurize the circular covering member to the substrate side.

  (10) In (8) or (9), the turntable includes a guide for positioning the substrate and the circular covering member by fitting into the central hole of the substrate and the central hole of the circular covering member. An optical recording medium manufacturing apparatus.

  (11) In the optical recording medium according to (10), the guide is capable of moving up and down and detaching the circular covering member from the resin material, and also serves as the circular covering member peeling device. Manufacturing equipment.

  (12) In any one of (8) to (11), the circular covering member transfer device is capable of peeling the circular covering member from the resin material by holding and lifting the circular covering member. An apparatus for manufacturing an optical recording medium, which also serves as the circular covering member peeling apparatus.

  (13) In any one of (8) to (12), there is provided a step pressurizing device for pressing in a thickness direction a step corresponding to the outer periphery of the circular covering member in the resin material. An optical recording medium manufacturing apparatus.

  (14) The optical recording according to any one of (8) to (12), further comprising a step removing device for removing a step corresponding to the outer periphery of the circular covering member in the resin material. Medium production equipment.

  In the present application, the term “radiation” is used in the meaning of a generic name for electromagnetic waves such as ultraviolet rays and particle beams such as electron beams, which have the property of curing a specific resin material in a fluid state.

  According to the present invention, the cover layer can be formed with a uniform thickness so that burrs and peeling do not occur.

  Hereinafter, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the optical recording medium manufacturing apparatus 10 according to the first embodiment of the present invention includes a turntable 14 for installing a disc-shaped substrate 12 having a center hole 12A substantially horizontally, A resin material supply device 18 for annularly supplying a radiation curable resin material 16 having translucency on the substrate 12 around the center hole 12A in a fluidized state, and a disk shape having a center hole 20A. A circular covering member transfer device 22 for transferring a circular covering member 20 having a light transmissivity smaller in diameter than the inner diameter of the recording area Ar onto the annular resin material 16, and irradiating the substrate 12 with radiation. A radiation irradiation device 24 (see FIG. 6) for curing the resin material 16 spread on the substrate 12, and a step corresponding to the outer periphery 20B of the circular covering member 20 in the resin material 16 spread on the substrate 12. Section 16B in thickness direction Includes a stepped portion pressurizing device 26 for pressurizing (see FIG. 8), the.

  The substrate 12 has an outer diameter of about 120 mm, a thickness of about 1.1 mm, and the center hole 12A has a diameter of about 15 mm. As a material of the substrate 12, for example, a resin such as polycarbonate, acrylic, epoxy, or the like can be used.

  An information layer (not shown) is formed on the surface of the substrate 12 on which pits and grooves are formed. The information layer is composed of one or more functional layers depending on the application. For example, when the optical recording medium is a ROM (Read Only Memory) type, the information layer is made of a reflective layer made of Al, Ag, Au, or the like. In the case of the RW (Re-Writable) type, in addition to the reflective layer, it is composed of layers such as a phase change material layer, a magneto-optical material layer, and a dielectric material layer. In the case of the R (Recordable) type, in addition to the reflective layer, it is composed of layers such as a phase change material layer, a recording layer of an organic dye layer or an inorganic material layer, and a dielectric material layer.

  The recording area Ar is set, for example, in a range of φ48 mm to φ116 mm. The clamping area for clamping the substrate 12 to the recording / reproducing apparatus is, for example, in the range of φ23 mm to φ33 mm.

  The turntable 14 has a structure in which a shaft portion 14B protrudes downward from a disk-shaped table portion 14A arranged substantially horizontally. The turntable 14 includes a guide 14 </ b> C for fitting into the center hole 12 </ b> A of the substrate 12 and the center hole 20 </ b> A of the circular covering member 20 to position the substrate 12 and the circular covering member 20. The table portion 14A sucks the substrate 12 by a negative pressure mechanism (not shown).

  The guide 14C is a stepped round bar-like body whose upper end is thinner than the main part below the guide 14C, penetrates the center of the table portion 14A and the shaft portion 14B in the vertical direction, and projects upward from the upper surface of the table portion 14A. ing. The upper end of the guide 14 </ b> C has a tapered shape that expands downward, and the outer diameter of the base portion is slightly smaller than the diameter of the center hole 20 </ b> A of the circular covering member 20. Further, the outer diameter of the main part of the guide 14C is slightly smaller than the diameter of the center hole 12A of the substrate 12. The guide 14 </ b> C can be moved up and down by a drive mechanism (not shown) so that the circular covering member 20 can be peeled from the resin material 16 while rising. That is, the guide 14C also serves as a circular covering member peeling device. The guide 14C is also engaged with the shaft portion 14B (not shown), and rotates together with the shaft portion 14B.

  Specifically, the resin material 16 is a light-transmitting acrylic or epoxy resin having a property of being cured when irradiated with radiation such as ultraviolet rays or electron beams. Here, translucency is not limited to the meaning of being transparent, and may be colored as long as it can transmit ultraviolet light or blue-violet light, for example.

  The resin material supply device 18 includes a nozzle 18 </ b> A for discharging the resin material 16 onto the substrate 12. The nozzle 18 </ b> A is movable and can approach / separate in the vicinity of the center hole 12 </ b> A of the substrate 12.

  In the circular covering member 20, the diameter of the center hole 20 </ b> A is not less than 0.1 mm and less than 15 mm, and is smaller than the diameter of the center hole 12 </ b> A of the substrate 12. As a material of the circular covering member 20, for example, a film-like material such as polyethylene terephthalate, polyethylene naphthalate, or polycarbonate can be used. In addition, the circular covering member 20 is not limited to the meaning of being transparent, and the material of the circular covering member 20 may be, for example, polyimide, polyamide, aramid, etc. as long as it can transmit radiation such as ultraviolet light and electron beam. Colored materials may be used.

  The circular covering member 20 preferably has water repellency at least on the contact surface with the resin material 16. Specific examples of such a material include a material in which silicon is applied to one side of a polyethylene terephthalate film.

  The circular covering member transfer device 22 includes a holding portion 22A configured so that the vicinity of the lower end is cylindrical and the circular covering member 20 is held at the lower end. An air hole (not shown) communicating with the lower end is formed in the cylindrical portion of the holding portion 22A. A negative pressure supply device (not shown) is connected to the vent hole, and the holding portion 22A is configured to adsorb and hold the circular covering member 20 with a negative pressure. The holding portion 22A may be configured to adsorb and hold the circular covering member 20 by, for example, static electricity.

  The circular covering member transfer device 22 includes a transfer device (not shown) for transferring the holding portion 22A, and the circular covering member 20 can be pressurized toward the substrate 12 side. Thereby, the thickness of the resin material 16 between the circular covering member 20 and the substrate 12 can be adjusted.

  In addition, when the guide 14C of the rotary table 14 is raised and the circular covering member 20 is peeled from the resin material 16, the circular covering member transfer device 22 is in a state where the holding portion 22A sandwiches the circular covering member 20 together with the guide 14C. The circular covering member 20 that has been lifted and separated is held by the holding portion 22A and carried out.

  The radiation irradiation device 24 is configured to cure the resin material 16 spread on the substrate 12 by irradiating the substrate 12 with radiation such as ultraviolet rays and electron beams from above.

  The step pressurizing device 26 comes into contact with the step 16B corresponding to the outer periphery 20B of the circular covering member 20 in the resin material 16 extended on the substrate 12 at the lower end in the vicinity of the lower end, and contacts the step 16B from above. Is provided with a pressing portion 26A for pressing in the thickness direction. The pressurizing unit 26A is configured to soften the stepped portion 16B by heating with a heater (not shown), ultrasonic oscillation, or the like. Further, the step portion pressurizing device 26 includes a transfer device (not shown) for transferring the pressurizing portion 26A, and the step portion 16B can be pressurized by urging the pressurizing portion 26A toward the substrate 12 side. ing. The step 16B can be softened by controlling the degree of curing by irradiation with radiation, by heating, oscillating ultrasonic waves, etc., and by pressing and leveling the step 16B, irradiating again with radiation, The leveled portion can be completely cured.

  Next, an optical recording medium manufacturing method using the optical recording medium manufacturing apparatus 10 will be described with reference to the flowchart of FIG.

  First, the substrate 12 is mounted on the turntable 14 substantially horizontally so that the surface on which the information layer is formed faces upward.

  Next, as shown in FIG. 1, the lower end of the nozzle 18A of the resin material supply device 18 is arranged near the surface of the substrate 12 and slightly outside the center hole 12A, and the turntable 14 is rotated. Then, a predetermined amount of the resin material 16 is supplied onto the substrate 12 from the lower end of the nozzle 18A (S102). As a result, the resin material 16 is annularly supplied around the center hole 12 </ b> A of the substrate 12.

  Next, the circular covering member 20 is held by the holding portion 22A of the circular covering member transfer device 22, and the circular covering member 20 is transferred to a position where the center of the circular covering member 20 coincides with the center of the rotary table 14. As shown in FIG. 3, the circular covering member 20 is transferred onto the annular resin material 16 so that the upper end portion of the guide 14C of the turntable 14 is fitted into the center hole 20A (S104). At this time, the circular covering member 20 is pressed toward the substrate 12 to adjust the thickness of the resin material 16 between the circular covering member 20 and the substrate 12 to a predetermined thickness.

  Next, as shown in FIG. 4, after raising the holding portion 22A, the turntable 14 is rotated to cause the resin material 16 to flow radially outward by centrifugal force (S106). At this time, the flow of the resin material 16 sandwiched between the circular covering member 20 and the substrate 12 is suppressed by the frictional force between them. In other words, the portion between the circular covering member 20 and the substrate 12 serves as a reservoir for the resin material 16, and the flow amount of the resin material 16 on the substrate 12 is buffered and stabilized. As a result, the resin material 16 is spread on the substrate 12 with a uniform thickness. It is also possible to increase the flow amount of the resin material 16 by pressing the circular covering member 20 toward the substrate 12 with the holding portion 22A while rotating the turntable 14. Furthermore, when the resin material 16 flows radially outward and the resin material 16 is spread over the entire surface of the substrate 12 to a thickness of about 100 μm, as shown in FIG. Stop. A step 16B is formed on the outer periphery 20B of the circular covering member 20 by adhering the resin material 16 so as to rise. Also, the resin material 16 is formed in a slightly raised shape near the outer periphery of the substrate 12 to form a stepped portion 16C, but this stepped portion 16C is outside the recording area Ar, so there is no practical problem.

  Next, as shown in FIG. 6, the resin material 16 is cured by irradiating the substrate 12 with radiation from the radiation irradiating device 24 (S108). In this step, it is preferable to irradiate radiation while rotating the substrate 12 when irradiating at least the vicinity of the outer periphery 20B of the circular covering member 20. By doing in this way, the resin material 16 can be hardened with the shape which suppressed the protrusion amount of the step part 16B of the resin material 16 formed along the outer periphery 20B of the circular coating | coated member 20. FIG. Also, in this process, when irradiating at least the vicinity of the outer periphery 20B of the circular covering member 20, the radiation of the stepped portion 16B can be softened by heating with a heater, oscillation of ultrasonic waves, etc. and cured with a certain degree of curing. Limit the amount of irradiation. In addition, since the circular covering member 20 has translucency, the resin material 16 under the circular covering member 20 is irradiated with radiation through the circular covering member 20 and is cured.

  Next, as shown in FIG. 7, the circular covering member 20 is sandwiched between the holding portion 22A of the circular covering member transfer device 22 and the guide 14C of the rotary table 14, and the guide 14C and the holding portion 22A are lifted to form a resin. The circular covering member 20 is peeled from the material 16 (S110). The peeled circular covering member 20 is held and carried out by the holding portion 22A.

  Next, as shown in FIG. 8, the pressurizing portion 26A of the stepped portion pressurizing device 26 is brought into contact with the stepped portion 16B of the resin material 16, and the stepped portion 16B is softened by heating with a heater, oscillation of ultrasonic waves, or the like. At the same time, the pressing portion 26A is urged in the thickness direction to pressurize the stepped portion 16B (S112). Thereby, the surface of the resin material 16 is leveled. In addition, the resin material 16 including the smoothed portion is completely cured by irradiating the portion of the resin material 16 that has been softened to some extent by heating with a heater or oscillating ultrasonic waves (S114). As a result, a cover layer 28 having a uniform thickness as shown in FIG. 9 (excluding the portion outside the recording area Ar) is formed, and the optical recording medium 30 is completed.

  Thus, since the resin material 16 is supplied around the center hole 12A of the substrate 12, the distance that the resin material flows is shorter than when the resin material is supplied to the central portion of the substrate. Therefore, the time required for spreading the resin material 16 is so short that the production efficiency is good.

  Even if the resin material 16 is supplied around the center hole 12A of the substrate 12, the flow of the resin material 16 can be controlled by the circular covering member 20, and the cover layer 28 can be formed with a uniform thickness.

  Next, a second embodiment of the present invention will be described.

  Compared to the first embodiment, the second embodiment is provided with a step portion deleting device 50 as shown in FIG. 10 instead of the step portion pressurizing device 26, and as shown in the flowchart of FIG. Instead of the step pressurizing step (S112), a step deleting step (S200) is provided. In the radiation irradiation step (S108), the entire resin material 16 including the step portion 16B is completely cured, and the radiation re-irradiation step (S114) is not performed. Since other steps are the same as those in the first embodiment, the same reference numerals as those in FIGS.

  The step portion deleting device 50 has a circular tool 52 having a cylindrical shape near the lower end and a blade formed on the lower end surface, and the stepped portion is brought into contact with the step portion 16B of the resin material 16 while rotating the circular tool 52. The part 16B is deleted. Note that the step portion 16B may be deleted by rotating the rotary table 14 without rotating the circular tool 52. Alternatively, the step 16B may be deleted by rotating both the circular tool 52 and the rotary table 14 in the reverse direction.

  As a result, as in the first embodiment, the cover layer 28 having a uniform thickness as shown in FIG. 9 (excluding the portion outside the recording area Ar) is formed, and the optical recording medium 30 is completed.

  Instead of the circular tool 52, for example, the step 16B may be deleted by moving along an annular step 16B along a circular path while rotating the end mill.

  Next, a third embodiment of the present invention will be described.

  The third embodiment is different from the first embodiment in that the circular covering member 20 is disposed between the radiation irradiation step (S108) and the circular covering member peeling step (S110) as shown in the flowchart of FIG. A notch forming step (S300) for forming a circular notch in the resin material 20 along the outer periphery 20B is provided, and the step pressurizing step (S112) is omitted. In the radiation irradiation step (S108) as in the second embodiment, the entire resin material 16 including the stepped portion 16B is completely cured, and the radiation re-irradiation step (S114) is not performed. Since other steps are the same as those in the first embodiment, the same reference numerals as those in FIGS.

  As shown in FIG. 13, in the notch forming step (S300), the circular covering member is pressed on the outer side in the radial direction from the step portion 16B by pressing the circular tool 32 having a sharp cylindrical shape at the lower end against the resin material 20. A circular cut is formed in the resin material 20 along the outer periphery 20 </ b> B of 20. Note that a circular cut may be formed in the resin material 20 by rotating the substrate 12 by bringing a tool such as a cutter into contact with only a part in the circumferential direction.

  Next, as shown in FIG. 14, the circular covering member 20 is sandwiched between the holding portion 22A of the circular covering member transfer device 22 and the guide 14C of the rotary table 14, and the guide 14C and the holding portion 22A are held and raised. Then, the circular covering member 20 is peeled from the resin material 16 (S110). Thereby, the resin material 16 around the circular covering member 20 including the step portion 16 </ b> B is also removed together with the circular covering member 20. Thereby, the cover layer 28 having a flat surface is formed (excluding the portion outside the recording area Ar), and the optical recording medium is completed. In this optical recording medium, the resin material 16 in the clamp area is removed, and the clamp mechanism does not come into contact with the inner peripheral portion of the cover layer 28 when mounted on a recording / reproducing apparatus. .

  Next, a fourth embodiment of the present invention will be described.

  The circular covering member 20 according to the first embodiment has a constant outer diameter on the outer peripheral side surface, whereas in the fourth embodiment, as shown in FIG. 15, the circular covering member 60 whose outer peripheral side surface is tapered. The circular covering member 60 is transferred onto the resin material 16 in such a posture that the outer peripheral side surface is expanded in the direction away from the substrate 12. Since other steps are the same as those in the first embodiment, the same reference numerals as those in FIGS. Thus, by using the circular covering member 60 whose outer peripheral side surface is tapered, the growth of the stepped portion 16B of the resin material 16 can be suppressed and the effect of easily peeling the circular covering member 60 from the cover layer 28 can be obtained. In addition, the step part 16B can be leveled by pressurization or deletion similarly to the first to third embodiments.

  In the first to fourth embodiments, the circular covering member 20 is sandwiched between the holding portion 22A of the circular covering member transfer device 22 and the guide 14C of the rotary table 14, and the guide 14C and the holding portion 22A are held and lifted. The circular covering member 20 is peeled from the resin material 16, but the guide 14C is held and raised in a state where the holding portion 22A of the circular covering member transfer device 22 is separated from the circular covering member 20, After peeling off the circular covering member 20 from the resin material 16, the circular covering member 20 may be held and carried out by the holding portion 22A.

  In the first to fourth embodiments, the guide 14C is raised to peel the circular covering member 20 from the resin material 16, but the circular covering member transfer device 22 is held without raising the guide 14C. The circular covering member 20 may be peeled from the resin material 16 by adsorbing the circular covering member 20 by the portion 22A and raising the holding portion 22A. In other words, the circular covering member transfer device 22 may also serve as the circular covering member peeling device. In this case, the guide 14C does not need to have a stepped shape.

  In the first to fourth embodiments, the diameter of the center hole 20A of the circular covering member 20 is 0.1 mm or more and less than 15 mm and smaller than the diameter of the center hole 12A of the substrate 12, but the resin material 16 is made uniform. A circular covering member having a diameter of the central hole larger than the diameter of the central hole 12 </ b> A of the substrate 12 may be used as long as it can be spread with a thickness and the circular covering member 20 can be reliably peeled from the resin material 16. For example, a circular covering member having a center hole diameter of about 15 mm or more and 20 mm or less may be used.

  Moreover, in the said 1st-4th embodiment, although the step part 16B is equalized by pressurization or deletion, if there is no problem practically, you may leave the step part 16B.

  In the first to fourth embodiments, the thickness of the cover layer is about 100 μm, but the thickness of the cover layer may be appropriately set according to the number of information layers stacked. For example, when two information layers are formed, the cover layer may have a thickness of 75 μm.

  In the first to fourth embodiments, the cover layer is formed only on one side of the substrate. However, the present invention can also be applied to a double-sided recording type optical recording medium in which the information layer is formed on both sides of the substrate. It is. In this case, the cover layer may be formed on both sides by the method as in the first to fourth embodiments. In the first to fourth embodiments, the thickness of the substrate is about 1.1 mm. In the case of the double-side recording type, for example, the thickness of the substrate may be 1.0 mm.

  As shown in Table 1, eight types of circular covering members 20 of A to H having different outer diameters and thicknesses are prepared, and these eight types of circular covering members 20 are used as in the first embodiment. An optical recording medium 30 was prepared. The main production conditions are shown below.

  In the resin material supply step (S102), an ultraviolet curable resin having a viscosity of about 2000 cp was used as the resin material 16. Moreover, the rotation speed of the turntable 14 was set to about 15 rpm, and about 3 g of the resin material 16 was supplied in a range of 11 to 25 mm from the center on the substrate 12. The resin material 16 has an annular shape having a radial width of about 14 mm and a height of about 2 mm.

  In the circular covering member transfer step (S106), the outer diameter and thickness are the values shown in Table 1 above, the material is polyethylene terephthalate, and the diameter of the central hole 20A is about 15 mm. 16, and while pressing the circular covering member 20 substantially horizontally, pressurizing it toward the substrate 12 and pushing it in for about 1 mm, the thickness of the resin material 16 between the circular covering member 20 and the substrate 12 is about 1 mm. Adjusted.

  In the resin material spreading step (S106), the rotation speed of the turntable 14 was first increased to about 300 rpm, and this rotation speed was maintained for a certain period of time, and then the rotation speed was increased to 1300 rpm.

  The thickness of the cover layer 28 of the optical recording medium 30 manufactured under the above manufacturing conditions was measured at a plurality of sites. The measurement results are shown in FIGS. 16 and 17 indicate the radial distance from the center of the optical recording medium to the measurement site. In addition, reference signs A to H in FIGS. 16 and 17 indicate that the curves with these marks are data of the optical recording medium 30 manufactured using the circular covering members 20 of A to H, respectively.

[Comparative example]
In contrast to the above example, one type of optical recording medium was manufactured without using the circular covering member 20. Other manufacturing conditions were the same as in the examples.

  The thickness of the cover layer of this optical recording medium was measured at a plurality of sites. The measurement results are shown in both FIG. 16 and FIG. 16 and 17 are data of an optical recording medium according to a comparative example manufactured without using the circular covering member 20.

  As shown in FIGS. 16 and 17, the optical recording medium 30 manufactured using the circular covering members 20 of A to H is an optical recording medium according to a comparative example manufactured without using the circular covering member 20. It was confirmed that the variation in the thickness of the cover layer was suppressed to a smaller level.

  The present invention can be used for an optical recording medium in which a cover layer thinner than a substrate is formed on a substrate and a central hole is formed.

1 is a side sectional view schematically showing the structure of a main part of an optical recording medium manufacturing apparatus according to a first embodiment of the present invention. The flowchart which shows the outline | summary of the manufacturing process of the optical recording medium using the manufacturing apparatus of the optical recording medium Side sectional view which shows typically the process of transferring a circular coating | coated member on the cyclic | annular resin material with the manufacturing apparatus. Side sectional view schematically showing a state in which the resin material is spread on a part of the substrate Side sectional view schematically showing a state in which the resin material is spread over the entire surface of the substrate. Side sectional view schematically showing the process of irradiating the substrate with radiation Side sectional view which shows typically the process of peeling the said circular coating | coated member from the resin material Side sectional view schematically showing the process of pressurizing the step of the resin material Side sectional view schematically showing the structure of an optical recording medium manufactured by the optical recording medium manufacturing apparatus Sectional drawing which shows typically the structure of the step part deletion apparatus of the manufacturing apparatus of the optical recording medium based on 2nd Embodiment of this invention The flowchart which shows the outline | summary of the manufacturing process of the optical recording medium based on the said 2nd Embodiment. Flowchart showing an outline of the manufacturing process of the optical recording medium according to the third embodiment of the present invention. Side sectional view which shows typically the process of forming a notch in a cover layer in the same 3rd embodiment Side sectional view which shows typically the process of peeling resin material in 3rd Embodiment Side sectional view which expands and shows the circular coating | coated member which concerns on 4th Embodiment of this invention. The graph which compares and compares the dispersion | variation in the thickness of the cover layer of the optical recording medium which concerns on the Example and comparative example of this invention The graph which compares and compares the dispersion | variation in the thickness of the cover layer of the optical recording medium based on the other Example of this invention, and the comparative example

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Manufacturing apparatus of optical recording medium 12 ... Board | substrate 12A ... Center hole 14 ... Rotary table 16 ... Resin material 18 ... Resin material supply apparatus 20, 60 ... Circular covering member 20A ... Center hole 20B ... Outer periphery 22 ... Circular covering member transfer Device 24 ... Radiation irradiation device 26 ... Step part pressurization device 28 ... Cover layer 30, 40 ... Optical recording medium 32, 52 ... Circular tool 50 ... Step part deletion device Ar ... Recording area S102 ... Resin material supply step S104 ... Circular coating Member transfer step S106 ... Resin material spreading step S108 ... Radiation irradiation step S110 ... Circular covering member peeling step S112 ... Step portion pressurization step S114 ... Radiation re-irradiation step S200 ... Step portion deletion step S300 ... Cut formation step

Claims (14)

  A resin material supplying step for supplying a radiation curable resin material having translucency onto a substrate having a disk shape and having a central hole in an annular shape around the central hole in a fluid state; A circular covering member transfer step of transferring a circular covering member having a disc shape having a hole and having a translucency whose outer diameter is smaller than the inner diameter of the recording area onto the annular resin material; and the substrate and the circular shape A resin material spreading step of rotating the coating member to flow the resin material radially outward by centrifugal force and spreading it on the substrate, and radiation irradiation for irradiating the substrate with radiation to cure the resin material And a circular covering member peeling step of peeling the circular covering member from the resin material. In claim 1,
A method for manufacturing an optical recording medium, wherein the circular covering member is pressed toward the substrate in at least one of the circular covering member transfer step and the spreading step. In claim 1 or 2,
In the radiation irradiating step, radiation is applied to the vicinity of the outer periphery of the circular covering member while rotating the substrate. In any one of Claims 1 thru | or 3,
A method of manufacturing an optical recording medium, wherein a circular covering member having at least a contact surface with the resin material having water repellency is used as the circular covering member. In any one of Claims 1 thru | or 4,
As the circular covering member, a circular covering member having a tapered outer peripheral side surface is used, and in the circular covering member transfer step, the circular covering member is placed in the posture in which the outer peripheral side surface expands in a direction away from the substrate. A method for producing an optical recording medium, wherein the method is transferred onto a recording medium. In any one of Claims 1 thru | or 5,
A step of pressing a step corresponding to the outer periphery of the circular covering member in the resin material in the thickness direction is provided after the step of peeling the circular covering member. Method. In any one of Claims 1 thru | or 5,
A method of manufacturing an optical recording medium, comprising: a step removing step for removing a step corresponding to an outer periphery of the circular covering member in the resin material after the circular covering member peeling step.   A rotary table for installing a disk-shaped substrate having a center hole substantially horizontally, and a radiation-curable resin material having translucency on the substrate are supplied in an annular shape around the center hole in a fluid state. And a circular material for transferring a circular covering member having a disc shape having a central hole and a translucency whose outer diameter is smaller than the inner diameter of the recording area onto the annular resin material. A covering member transfer device, a radiation irradiation device for irradiating the substrate with radiation and curing the resin material spread on the substrate, and a circle for peeling the circular covering member from the resin material An apparatus for producing an optical recording medium, comprising: a covering member peeling device. In claim 8,
The apparatus for manufacturing an optical recording medium, wherein the circular covering member transfer device can pressurize the circular covering member toward the substrate. In claim 8 or 9,
An apparatus for manufacturing an optical recording medium, wherein the turntable includes a guide for positioning the substrate and the circular covering member by fitting into the central hole of the substrate and the central hole of the circular covering member. In claim 10,
2. The optical recording medium manufacturing apparatus according to claim 1, wherein the guide is movable up and down and can be lifted to peel the circular covering member from the resin material, and also serves as the circular covering member peeling device. In any of claims 8 to 11,
The circular covering member transfer device is capable of peeling the circular covering member from the resin material by holding and lifting the circular covering member, and also serves as the circular covering member peeling device. Medium production equipment. In any one of Claims 8 thru | or 12.
An apparatus for manufacturing an optical recording medium, comprising: a step pressurizing device for pressing in a thickness direction a step corresponding to the outer periphery of the circular covering member in the resin material. In any one of Claims 8 thru | or 12.
An apparatus for producing an optical recording medium, comprising: a step removing device for removing a step corresponding to the outer periphery of the circular covering member in the resin material.

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