JP2009054250A - Substrate for magnetic recording medium, and magnetic disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for magnetic recording medium to be held in parallel at a fixed interval when a plurality of substrates are stacked. <P>SOLUTION: The substrate 1 for magnetic recording medium has a disk like substrate 2, a projection 3 which protrudes at a center of the substrate 2 and whose width is gradually narrowed toward the tip part thereof and a recess which is formed in a position corresponding to the projecting part 3 in the surface opposite to the surface where the projection 3 is protrudes and whose width is gradually narrowed toward the depth direction thereof. The inclination of a side surface of the projection 3 is equal to the inclination of an inner surface of the recess and the width of a top part 4 of the projection 3 is narrower than the width of the recess in an aperture and wider than the width of a bottom surface 5 of the recess. A magnetic film is deposited on the surface of the substrate 1 for magnetic recording medium to form the magnetic recording medium. The projection 3 of the magnetic recording medium is fitted to the recess of the other magnetic recording medium to stack and fix the plurality of substrates. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin-made magnetic recording medium substrate used for a substrate of a magnetic disk recording device, and a magnetic disk device using the magnetic recording medium substrate.

  In a magnetic disk device used for a computer or the like, an aluminum substrate or a glass substrate is used as a substrate for a magnetic recording medium. The magnetic recording medium substrate has a disk shape, and a through-hole penetrating in the thickness direction of the substrate is formed at the center of the substrate. A metal magnetic thin film is formed on this substrate, and data is recorded by magnetizing the metal magnetic thin film with a magnetic head (for example, Patent Document 1, Patent Document 2, and Patent Document 3).

  Attempts have also been made to adopt a resin substrate such as a plastic substrate as a substrate for a magnetic recording medium used in a magnetic disk device. In this case, a magnetic recording medium is produced by forming a magnetic layer on a resin substrate (for example, Patent Document 4 and Patent Document 5).

  The magnetic disk device has a structure in which one or a plurality of disk-shaped magnetic recording media are coaxially arranged and are rotationally driven by a spindle motor. Data reading and writing are performed by a magnetic head provided facing the magnetic recording medium.

  The disk-shaped magnetic recording medium is fixed to the rotating shaft of the spindle motor by a fixing member. A spindle motor hub is fitted into the through hole of the magnetic recording medium. Then, the peripheral portion of the through hole is formed by a base that contacts the peripheral portion of the through hole from one surface (lower surface) of the magnetic recording medium and a fixing member that contacts the peripheral portion of the through hole from the other surface (upper surface). The magnetic recording medium is held by applying force from both sides.

  The magnetic recording medium attached to the rotation shaft of the spindle motor is driven to rotate by the rotation of the spindle motor. Then, magnetic recording of data or the like is performed on the track by the magnetic head on the magnetic film on the surface of the magnetic recording medium. In addition, data recorded on the track of the magnetic film is reproduced by the magnetic head.

  When a plurality of magnetic recording media are installed in the magnetic disk device, the plurality of magnetic recording media are fitted to the spindle motor hub, and a spacer fitted to the spindle motor hub is provided between the magnetic recording media. The magnetic recording medium is laminated in the axial direction of the hub. The spacer keeps the interval between the magnetic recording media constant. The plurality of magnetic recording media are held by the fixing member, the spacer, and the base.

JP 2003-54965 A JP 2003-55001 A JP 2000-163740 A Japanese Patent Laid-Open No. 10-320762 JP 2001-300080 A

  In a magnetic disk device having a plurality of magnetic recording media, it is necessary to keep the intervals between the magnetic recording media constant and keep the magnetic recording media in parallel. Furthermore, it is necessary to match the rotation axes of the magnetic recording media. In the prior art, by interposing a spacer between the magnetic recording media, the interval between the magnetic recording media is kept constant, and the magnetic recording media are maintained in parallel. As described above, in the prior art, it is necessary to provide a spacer in order to keep the interval between the magnetic recording media constant and keep the magnetic recording media in parallel.

  The present invention solves the above-described problem, and a substrate for a magnetic recording medium that can be held in parallel at regular intervals without using a spacer when a plurality of sheets are stacked, and for the magnetic recording medium An object of the present invention is to provide a magnetic disk device including a magnetic recording medium manufactured by a substrate.

According to a first aspect of the present invention, a disk-shaped substrate having a flat surface, a center of the substrate and protruding in the thickness direction of the substrate, the width gradually decreases toward the tip, A protrusion having a top at the tip, and a recess formed on the surface opposite to the surface from which the protrusion protrudes, at a position corresponding to the protrusion, and gradually narrowing in the depth direction; And the inclination of the side surface of the protrusion is equal to the inclination of the inner surface of the recess, and the width of the top of the protrusion is narrower than the width of the opening of the recess and wider than the width of the bottom of the recess. A magnetic recording medium substrate.
Further, the second embodiment of the present invention is provided with a disk-shaped substrate having a flat surface, and provided in the center of the substrate so as to protrude in the thickness direction of the substrate, and the width gradually decreases toward the tip. A protrusion having a top at the tip and a recess formed at a position corresponding to the protrusion on the surface opposite to the surface from which the protrusion protrudes and gradually narrowing in the depth direction. And the inclination of the side surface of the projection and the inclination of the inner surface of the recess are equal, the thickness of the tip of the projection is thicker than the thickness of the substrate, and the width of the top of the projection is The magnetic recording medium substrate is narrower than the width of the opening of the recess and substantially equal to the width of the bottom surface of the recess.
According to a third aspect of the present invention, there is provided the magnetic recording medium substrate according to the second aspect, wherein a fitting portion is provided at a position away from the center of the substrate at the top of the protrusion. In the bottom surface of the concave portion, a fitted portion is provided at a position away from the center of the substrate by the predetermined distance.
According to a fourth aspect of the present invention, there is provided the magnetic recording medium substrate according to the third aspect, wherein the top of the protrusion has a flat circular shape, and the fitting portion has a continuous uneven shape. And provided along the circumference of the top of the protrusion, the bottom surface of the recess has a flat circular shape, and the mating portion has a continuous uneven shape and has a circle on the bottom surface. It is provided along the circumference.
According to a fifth aspect of the present invention, there is provided the magnetic recording medium substrate according to any one of the second to fourth aspects, wherein another recess is formed on the bottom surface of the recess. It is characterized by.
The sixth embodiment of the present invention is a disk-shaped substrate having a flat surface, and is provided in the center of the substrate so as to protrude in the thickness direction of the substrate, and the width gradually decreases toward the tip. A protrusion having a top at the tip and a recess formed at a position corresponding to the protrusion on the surface opposite to the surface from which the protrusion protrudes and gradually narrowing in the depth direction. And the inclination of the side surface of the protrusion and the inclination of the inner surface of the recess are equal, the width of the top of the protrusion is narrower than the width of the opening of the recess, and the width of the bottom of the recess A magnetic recording medium in which a magnetic film is formed on the surface of a wide magnetic recording medium substrate, and a magnetic recording section in which a plurality of magnetic recording media are stacked by fitting the protrusions into recesses of another magnetic recording medium; A housing that fits into a recess of a magnetic recording medium provided at the bottom of the magnetic recording section. When a driving means for rotationally driving the magnetic recording unit through the hub, a magnetic disk apparatus characterized by having a magnetic head for recording or reproducing of the magnetic recording medium.
The seventh embodiment of the present invention is a disk-shaped substrate having a flat surface, and is provided in the center of the substrate so as to protrude in the thickness direction of the substrate, and the width gradually decreases toward the tip. A protrusion having a top at the tip and a recess formed at a position corresponding to the protrusion on the surface opposite to the surface from which the protrusion protrudes and gradually narrowing in the depth direction. And the inclination of the side surface of the projection and the inclination of the inner surface of the recess are equal, the thickness of the top of the projection is thicker than the thickness of the substrate, and the width of the top of the projection is A magnetic recording medium having a magnetic film formed on the surface of a magnetic recording medium substrate that is narrower than the width of the opening of the concave portion and approximately equal to the width of the bottom surface of the concave portion, and the protrusion is fitted into the concave portion of another magnetic recording medium. A magnetic recording unit in which a plurality of magnetic recording media are stacked together, and the magnetic recording unit A hub that fits into a recess of a magnetic recording medium provided at a lowermost part; a drive unit that rotationally drives the magnetic recording unit via the hub; and a magnetic head that performs recording or reproduction of the magnetic recording medium. It is a magnetic disk apparatus characterized by having.
According to an eighth aspect of the present invention, there is provided the magnetic disk apparatus according to the seventh aspect, wherein a fitting portion is provided at a position away from the center of the substrate at a top portion of the protrusion, On the bottom surface of the concave portion, a fitted portion is provided at a position separated from the center of the substrate by the predetermined distance, and the protruding portion is fitted into the concave portion of another magnetic recording medium, thereby The fitting portion is fitted.
According to a ninth aspect of the present invention, there is provided the magnetic disk apparatus according to the eighth aspect, wherein the top of the protrusion has a flat circular shape, and the fitting portion has a continuous uneven shape. Provided along the circumference of the top of the protrusion, the bottom surface of the recess has a flat circular shape, and the fitted portion has a continuous irregular shape along the circumference of the bottom surface. It is characterized by being provided.

  According to the present invention, a protrusion and a recess are provided in the center of the substrate, and the protrusions of the magnetic recording medium substrate are fitted into the recesses of another magnetic recording medium substrate. The recording medium substrate (magnetic recording medium) can be stacked and fixed. Further, by making the inclination of the side surfaces of the protrusions equal to the inclination of the inner surfaces of the recesses, it becomes possible to align the axes of the magnetic recording medium substrates when a plurality of magnetic recording medium substrates are stacked. Furthermore, it becomes possible to fix a plurality of magnetic recording medium substrates in parallel at regular intervals.

[First Embodiment]
A magnetic recording medium substrate according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a magnetic recording medium substrate according to the first embodiment of the present invention. 2 is a cross-sectional view of the magnetic recording medium substrate according to the first embodiment of the present invention, and is a cross-sectional view taken along the line II-II of FIG.

  The magnetic recording medium substrate 1 according to the first embodiment includes a disk-shaped substrate 2 having a flat surface and a protrusion 3 provided at the center of the substrate 2. Then, a magnetic film is formed on the surface of the magnetic recording medium substrate 1 to produce a magnetic recording medium used in the magnetic disk device.

  The protrusion 3 is provided on one surface of the substrate 2 and protrudes in the thickness direction of the substrate 2. The protrusion 3 has, for example, a circular shape in cross section parallel to the substrate 2. The diameter of the cross section of the protrusion 3 gradually decreases toward the tip of the protrusion 3. The protrusion 3 has a top 4 at the tip. That is, the side surface of the protrusion 3 is a slope formed obliquely with respect to the thickness direction of the magnetic recording medium substrate 1. The side surface of the protrusion 3 may be linear or curved. Further, the top 4 of the protrusion 3 is a flat surface.

  In the magnetic recording medium substrate 1, a surface opposite to the surface from which the protrusion 3 protrudes is formed with a recess in the direction in which the protrusion 3 protrudes. That is, the magnetic recording medium substrate 1 has a shape in which the center is recessed from one surface toward the opposite surface. This recess has a circular cross-sectional shape parallel to the substrate 2, for example. The concave portion formed in the magnetic recording medium substrate 1 has a maximum diameter at the opening and gradually decreases in the depth direction. That is, the inner surface of the recess is a slope formed obliquely with respect to the thickness direction of the magnetic recording medium substrate 1. The inner surface of the recess may be linear or curved. Further, the bottom surface 5 of the concave portion (the surface on the side opposite to the top portion 4 of the protruding portion 3) is a flat surface.

  The thickness of the magnetic recording medium substrate 1 is a constant thickness t1. That is, the thickness of the substrate 2, the thickness of the side surface of the protrusion 3, and the thickness of the top 4 of the protrusion 3 are constant thickness t1. Further, both surfaces of the magnetic recording medium substrate 1 are kept parallel. For example, the inclination of the side surface of the protrusion 3 and the inclination of the inner surface of the recess corresponding to the protrusion 3 are the same inclination. Further, the diameter d1 of the top 4 of the protrusion 3, the diameter d2 of the bottom 5 of the recess (the surface opposite to the top 4), and the diameter d3 of the opening of the recess satisfy the relationship of diameter d2 <diameter d1 <diameter d3. Yes.

  Then, a magnetic recording medium is manufactured by forming a magnetic film such as a Co-based alloy on the surface of the magnetic recording medium substrate 1 by a film forming method such as sputtering.

  A magnetic disk device according to an embodiment of the present invention includes a plurality of magnetic recording media stacked. Here, a magnetic disk device provided with a plurality of magnetic recording medium substrates 1 stacked thereon will be described with reference to FIG. FIG. 3 is a cross-sectional view of the substrate showing a state in which the magnetic recording medium substrates according to the first embodiment of the present invention are stacked. In the magnetic disk device, a plurality of magnetic recording media having magnetic films formed on the surface of the magnetic recording medium substrate 1 are stacked. Here, for ease of explanation, FIG. 3 shows a state in which the magnetic recording medium substrates 1 are stacked.

  As shown in FIG. 3A, a plurality of magnetic recording medium substrates 1 having the same shape are stacked. That is, the plurality of magnetic recording medium substrates 1 are overlapped by fitting the protrusions 3 of the magnetic recording medium substrate 1 into the recesses corresponding to the protrusions 3 of the other magnetic recording medium substrates 1. Here, as an example, two magnetic recording medium substrates 1 are stacked. A superposition of a plurality of magnetic recording media (magnetic recording medium substrate 1) corresponds to an example of the “magnetic recording portion” of the present invention.

  The side surfaces of the protrusions 3 of one magnetic recording medium substrate 1 are in contact with the inner surfaces of the recesses corresponding to the protrusions 3 of the other magnetic recording medium substrate 1, thereby fixing the plurality of magnetic recording medium substrates 1. The Since the diameter d1 of the top 4 of the protrusion 3 is larger than the diameter d2 of the bottom surface 5 of the recess, the top 4 of the protrusion 3 provided on one magnetic recording medium substrate 1 is the other magnetic recording medium substrate. 1 does not come into contact with the bottom surface 5 of the recess formed in 1. This creates a gap between the two magnetic recording medium substrates 1. The width of this gap is the width L1.

  Then, as shown in FIG. 3B, a hub 6 connected to a spindle motor 8 is fitted into a concave portion of one magnetic recording medium substrate 1 (magnetic recording medium), and the magnetic recording medium substrate 1 ( By pressing the magnetic recording medium substrate 1 from the upper surface of the magnetic recording medium), the two magnetic recording medium substrates 1 (magnetic recording medium) are fixed to the rotation shaft of the spindle motor 8. The hub 6 has a cylindrical shape, and the distal end portion 7 of the hub 6 gradually decreases in diameter toward the distal end of the hub 6. By fitting the hub 6 into the recess of the magnetic recording medium substrate 1, the tip 7 of the hub 6 comes into contact with the bottom surface 5 of the recess of the magnetic recording medium substrate 1 and the inner surface of the recess. In this state, by pressing the magnetic recording medium substrate 1 from the upper surface of the magnetic recording medium substrate 1, the two magnetic recording medium substrates 1 (magnetic recording media) are fixed to the rotation shaft of the spindle motor 8. . The spindle motor 8 corresponds to an example of the driving means of the present invention.

  By transmitting torque generated by the rotation of the spindle motor 8 to the magnetic recording medium substrate 1 (magnetic recording medium), the magnetic recording medium substrate 1 (magnetic recording medium) is rotationally driven. In the plurality of magnetic recording medium substrates 1 (magnetic recording media), the side surfaces of the protrusions 3 are in contact with the inner surfaces of the recesses. By this contact, torque due to rotation of the spindle motor 8 is transmitted to each magnetic recording medium substrate 1.

  Then, magnetic recording of data or the like is performed on the magnetic film on the surface of the magnetic recording medium by a magnetic head (not shown). In addition, data recorded on the track of the magnetic film is reproduced by the magnetic head.

  As described above, a plurality of magnetic recording medium substrates 1 without using spacers are provided by providing the protrusion 3 having one surface protruding and the other surface recessed at the center of the magnetic recording medium substrate 1. (Magnetic recording medium) can be stacked and fixed to the rotation shaft of the spindle motor 8. As a result, the number of parts of the magnetic disk device can be reduced, and the assembly of the magnetic disk device can be simplified.

  Then, by matching the inclination of the side surface of the protrusion 3 with the inclination of the inner surface of the recess, when the plurality of magnetic recording medium substrates 1 (magnetic recording media) are stacked, the side surface of the protrusion 3 and the inner surface of the recess are A plurality of magnetic recording medium substrates 1 (magnetic recording media) can be aligned with each other. Furthermore, by making the diameter d1 of the top 4 of the protrusion 3 larger than the diameter d2 of the bottom surface 5 of the recess, a plurality of magnetic recording medium substrates 1 (magnetic recording media) are held in parallel at intervals of the width L1. Is possible. As described above, by using the magnetic recording medium substrate 1, it is possible to define the substrate spacing, the parallel alignment between the substrates, and the axial alignment between the substrates in the plurality of magnetic recording medium substrates 1 (magnetic recording media). It becomes possible. Further, the torque caused by the rotation of the spindle motor 8 can be transmitted to each magnetic recording medium substrate 1 (magnetic recording medium) by the contact between the side surface of the protrusion 3 and the inner surface of the recess.

  In the first embodiment, the top 4 of the protrusion 3 is formed on a flat surface, and the bottom surface 5 of the recess is formed on a flat surface. This is an example, and any of them may not be formed on a flat surface. When a plurality of magnetic recording medium substrates 1 (magnetic recording media) are stacked, the side surfaces of the protrusions 3 and the inner surfaces of the recesses are in contact with each other, and a gap is formed between the top 4 and the bottom surface 5 so that the width of the substrate is increased. The top 4 and the bottom 5 may not be formed on a flat surface as long as they are held at the interval L1.

  Moreover, the cross-sectional shape of the protrusion part 3 and the cross-sectional shape of a recessed part are circular. This is an example, and the cross-sectional shape of the protrusion 3 and the cross-sectional shape of the recess may be polygonal. Thus, even when the cross-sectional shape of the protrusion 3 and the cross-section of the recess are polygonal, when the plurality of magnetic recording medium substrates 1 are stacked, the side surface of the protrusion 3 and the inner surface of the recess come into contact with each other. The magnetic recording medium substrate 1 can be fixed.

  Further, conventionally, a through hole is formed in the center of a magnetic recording medium substrate (magnetic recording medium), and a spindle motor hub is passed through the through hole, whereby the magnetic recording medium substrate (magnetic recording medium) is formed. It was fixed to the rotating shaft of the spindle motor. Therefore, it is necessary to form a through hole by punching in the center of the magnetic recording medium substrate (magnetic recording medium). As a result, there is a risk of distortion occurring near the center of the magnetic recording medium substrate (magnetic recording medium).

  In the magnetic recording medium substrate 1 according to the first embodiment, the plurality of magnetic recording medium substrates 1 are overlapped and fixed to the rotation shaft of the spindle motor by the protrusions 3 formed on each magnetic recording medium substrate 1. Therefore, it is not necessary to form a through hole for penetrating the hub of the spindle motor at the center of the magnetic recording medium substrate 1. Therefore, it is possible to prevent the occurrence of distortion due to punching.

  In the first embodiment, as an example, two magnetic recording medium substrates 1 (magnetic recording media) are stacked and fixed. As another example, three or more magnetic recording medium substrates 1 (magnetic recording media) may be stacked and fixed.

(Material of substrate 1 for magnetic recording medium)
Various substrates can be used for the magnetic recording medium substrate 1 in addition to a thermoplastic resin, a thermosetting resin, or an actinic radiation curable resin.

  As the thermoplastic resin, the magnetic recording medium substrate 1 includes, for example, polycarbonate, polyetheretherketone resin (PEEK resin), cyclic polyolefin resin, methacrylstyrene resin (MS resin), polystyrene resin (PS resin), polyetherimide. Resin (PEI resin), ABS resin, polyester resin (PET resin, PBT resin, etc.), polyolefin resin (PE resin, PP resin, etc.), polysulfone resin, polyethersulfone resin (PES resin), polyarylate resin, polyphenylene sulfide resin Polyamide resin or acrylic resin can be used. Further, as the thermosetting resin, for example, phenol resin, urea resin, unsaturated polyester resin (such as BMC resin), silicon resin, urethane resin, epoxy resin, polyimide resin, polyamideimide resin, or polybenzimidazole resin. Can be used. In addition, polyethylene naphthalate resin (PEN resin) or the like can be used.

  As the actinic radiation curable resin, for example, an ultraviolet curable resin is used. Examples of the ultraviolet curable resin include an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, an ultraviolet curable epoxy resin, and an ultraviolet curable silicon. Examples thereof include an ultraviolet resin and an ultraviolet curable acrylic resin.

  Moreover, it is preferable to accelerate | stimulate hardening reaction using a photoinitiator, when it hardens | cures by irradiating an active ray to the coated layer before hardening. At this time, a photosensitizer may be used in combination.

  Further, when oxygen in the air suppresses the curing reaction, active rays can be irradiated, for example, in an inert gas atmosphere in order to reduce or remove the oxygen concentration. As the actinic ray, infrared rays, visible light, ultraviolet rays, and the like can be appropriately selected. However, ultraviolet rays are preferably selected in terms of productivity such as curing speed, but are not particularly limited. Further, the curing reaction may be strengthened by heating during irradiation with active rays or before and after.

  Further, the magnetic recording medium substrate 1 may use a liquid crystal polymer, an organic / inorganic hybrid resin (for example, a polymer component in which silicon is incorporated as a skeleton), or the like. The resins listed above are examples of resins used for the magnetic recording medium substrate 1, and the substrate according to the present invention is not limited to these resins. Two or more kinds of resins may be mixed to form a resin substrate, or may be a substrate in which different components are adjacent as separate layers.

  Further, it is desirable that the resin as the base material has as high a heat resistance temperature or glass transition temperature Tg as possible. Since the magnetic layer is formed by sputtering on the resin-made magnetic recording medium substrate 1, the heat-resistant temperature or the glass transition temperature Tg is preferably equal to or higher than the sputtering temperature. For example, a resin having a heat resistant temperature or a glass transition temperature Tg of 150 ° C. or higher is preferably used, and a resin having a temperature of 200 ° C. or higher is more preferably used.

  As typical resins having a heat resistance temperature or glass transition temperature Tg of 150 ° C. or higher, resins such as phenol, melanin, epoxy, polyphenylene sulfide, unsaturated polyester filled with heat resistant polycarbonate, silicon resin, Teflon resin, inorganic filler, Examples include polyethersulfone resin (PES resin), polyetherimide resin (PEI resin), polyamideimide resin, polyimide resin, polybenzimidazole resin, BMC resin, or liquid crystal polymer. More specifically, polyethersulfone resin (PES resin), Udel (Solvay Advanced Polymers), polyetherimide resin (PEI resin), Ultem (Nippon GE Plastics), polyamideimide resin, Torlon (Solvaide) Bunst Polymers), polyimide resin (thermoplastic), Aurum (Mitsui Chemicals), polyimide (thermosetting), Upilex (Ube Industries), or polybenzimidazole resin, PBI / Celazole (Clariant Japan) . Moreover, SUMIKASUPER LCP (Sumitomo Chemical) is mentioned as a liquid crystal polymer, and Victrex (Victrex MC) is mentioned as a polyether ether ketone.

  The magnetic recording medium substrate 1 is manufactured by a molding method such as an injection molding method, a casting molding method, a sheet molding method, an injection compression molding method, or a compression molding method, using a mold having a shape corresponding to the substrate. be able to.

  In addition, by molding the magnetic recording medium substrate 1 by the injection molding method or the like, at least one of the outer diameter of the substrate or the shape of the outer peripheral end can be formed simultaneously. That is, a mold used for an injection molding method or the like is manufactured in accordance with the dimension of the outer diameter of the substrate, and the mold is used to complete the outer diameter dimension at the time of resin molding. In addition, by fabricating a mold in accordance with the shape of the outer peripheral end of the substrate and using the mold, the shape of the outer peripheral end is formed at the time of resin molding.

[Second Embodiment]
Next, a magnetic recording medium substrate according to a second embodiment of the present invention will be described with reference to FIG.

  A magnetic recording medium substrate 10 according to the second embodiment includes a disk-shaped substrate 11 having a flat surface and a protrusion 12 provided at the center of the substrate 11. Then, by forming a magnetic film on the surface of the magnetic recording medium substrate 10, a magnetic recording medium used in the magnetic disk device is manufactured.

  The protrusion 12 is provided on one surface of the substrate 11 and protrudes in the thickness direction of the substrate 11. The protrusion 12 has a circular cross-sectional shape parallel to the substrate 11, for example. The diameter of the cross section of the protruding portion 12 gradually decreases toward the top portion 13 of the protruding portion 12. And the protrusion part 12 has the top part 13 at the front-end | tip. That is, the side surface of the protrusion 12 is a slope formed obliquely with respect to the thickness direction of the magnetic recording medium substrate 10. The side surface of the protrusion 12 may be linear or may be a curved surface. Moreover, the top part 13 of the projection part 12 is a flat surface.

  In the magnetic recording medium substrate 10, a concave portion is formed on the surface opposite to the surface from which the protruding portion 12 protrudes in the direction in which the protruding portion 12 protrudes. That is, the magnetic recording medium substrate 10 has a shape in which the center is recessed from one surface toward the opposite surface. This recess has a circular cross-sectional shape parallel to the substrate 2, for example. The concave portion formed in the magnetic recording medium substrate 10 has a maximum diameter on the surface of the magnetic recording medium substrate 10 and gradually decreases in the depth direction. That is, the inner surface of the recess is a slope formed obliquely with respect to the thickness direction of the magnetic recording medium substrate 10. The inner surface of the recess may be linear or curved. Further, the bottom surface 14 of the concave portion (the surface on the side opposite to the top portion 13 of the protrusion 12) is a flat surface.

  The thickness of the substrate 11 is a constant thickness t2. Moreover, the thickness of the top part 13 of the projection part 12 is a constant thickness t3. The thickness t3 of the top portion 13 of the protrusion 12 is thicker than the thickness t2 of the substrate 11. In other words, the thickness t2 of the substrate 11 and the thickness t3 of the top portion 13 satisfy the relationship of thickness t3> thickness t2.

  Furthermore, both surfaces of the magnetic recording medium substrate 10 are kept parallel. For example, the inclination of the side surface of the protrusion 12 and the inclination of the inner surface of the recess corresponding to the protrusion 12 are the same.

  Further, the diameter d4 of the top portion 13 of the protrusion 12 is equal to the diameter d5 of the bottom surface 14 of the recess (the surface opposite to the top portion 13 of the protrusion 12). That is, the diameter d4 of the top portion 13 and the diameter d5 of the bottom surface 14 satisfy the relationship of diameter d4 = diameter d5. Further, the diameter d6 of the concave portion in the opening is larger than the diameter d4 of the top portion 13 and the diameter d5 of the bottom surface 14 of the concave portion. That is, the diameter d4 of the top portion 13, the diameter d5 of the bottom surface 14, and the diameter d6 of the recess in the opening satisfy the relationship of diameter d4 = diameter d5 <diameter d6.

  Then, a magnetic recording medium is manufactured by forming a magnetic film on the surface of the magnetic recording medium substrate 10 by a film forming method such as sputtering.

  As described above, the magnetic disk device according to the embodiment of the present invention includes a plurality of magnetic recording media stacked. Here, a magnetic disk device provided with the magnetic recording medium substrate 10 overlaid will be described with reference to FIG. FIG. 5 is a sectional view of the substrate showing a state in which the magnetic recording medium substrates according to the second embodiment of the present invention are stacked. In the magnetic disk device, a plurality of magnetic recording media each having a magnetic film formed on the surface of the magnetic recording medium substrate 10 are stacked. Here, for ease of explanation, FIG. 5 shows a state in which the magnetic recording medium substrates 10 are stacked.

  As shown in FIG. 5, magnetic recording medium substrates 10 having the same shape are stacked. That is, the plurality of magnetic recording medium substrates 10 are overlapped by fitting the protrusions 12 of the magnetic recording medium substrate 10 into the recesses corresponding to the protrusions 12 of the other magnetic recording medium substrates 10. Here, as an example, two magnetic recording medium substrates 10 are stacked. A stack of a plurality of magnetic recording media (magnetic recording medium substrate 10) corresponds to an example of the “magnetic recording portion” of the present invention.

  The top 13 of the protrusion 12 of one magnetic recording medium substrate 10 is in contact with the bottom surface 14 of the recess corresponding to the protrusion 12 of the other magnetic recording medium substrate 10. Furthermore, the side surface of the protrusion 12 of one magnetic recording medium substrate 10 is in contact with the side surface of the recess corresponding to the protrusion 12 of the other magnetic recording medium substrate 10. The plurality of magnetic recording medium substrates 10 are fixed by the contact. Since the diameter d4 of the top 13 of the protrusion 12 is equal to the diameter d5 of the bottom surface 14 of the recess, the top 13 of the protrusion 12 provided on one magnetic recording medium substrate 10 is the other magnetic recording medium substrate 10. In contact with the bottom surface 14 of the recess formed. Accordingly, there is no gap between the two magnetic recording medium substrates 10 at the center of the magnetic recording medium substrate 10.

  On the other hand, since the thickness t3 of the top portion 13 of the protrusion 12 is thicker than the thickness t2 of the substrate 11, a gap is generated between the two magnetic recording medium substrates 10 in the substrate 11. The width L2 of the gap corresponds to the difference between the thickness t3 of the top portion 13 of the protrusion 12 and the thickness t2 of the substrate 11. With such a configuration, it is possible to change the width L2 of the gap between the two magnetic recording medium substrates 10 by changing the thickness t3 of the top portion 13 of the protruding portion 12.

  As in the first embodiment, a hub connected to the spindle motor is fitted into a recess corresponding to the protrusion 12 of one magnetic recording medium substrate 10 (magnetic recording medium). Then, by pressing the magnetic recording medium substrate 10 from the upper surface of the magnetic recording medium substrate 10 (magnetic recording medium), the two magnetic recording medium substrates 10 (magnetic recording medium) are moved with respect to the rotation axis of the spindle motor. Fix it.

  By transmitting the torque generated by the rotation of the spindle motor to the magnetic recording medium substrate 10 (magnetic recording medium), the magnetic recording medium substrate 10 (magnetic recording medium) is rotationally driven. In the plurality of magnetic recording medium substrates 10 (magnetic recording media), the top portion 13 of the projection 12 is in contact with the bottom surface 14 of the recess, and the side surface of the projection 12 is in contact with the inner surface of the recess. By these contacts, torque due to the rotation of the spindle motor is transmitted to each magnetic recording medium substrate 10.

  Then, magnetic recording of data or the like is performed on the magnetic film on the surface of the magnetic recording medium by a magnetic head (not shown). In addition, data recorded on the track of the magnetic film is reproduced by the magnetic head.

  As described above, a plurality of magnetic recording medium substrates 10 are provided without providing spacers by providing the projection 12 having one surface protruding and the other surface recessed at the center of the magnetic recording medium substrate 10. (Magnetic recording medium) can be stacked and fixed to the rotating shaft of the spindle motor. As a result, the number of parts of the magnetic disk device can be reduced, and the assembly of the magnetic disk device can be simplified.

  Then, the inclination of the side surface of the protrusion 12 and the inclination of the inner surface of the recess are matched, and the diameter d4 of the top portion 13 of the protrusion 12 and the diameter d5 of the bottom surface 14 of the recess are made equal. When the (magnetic recording medium) is stacked, the top portion 13 of the projection 12 and the bottom surface 14 of the recess come into contact with each other, and the side surface of the projection 12 and the inner surface of the recess come into contact with each other. Thereby, the axial alignment of the plurality of magnetic recording field mode substrates 10 (magnetic recording media) becomes possible. The plurality of magnetic recording medium substrates 10 (magnetic recording media) are held in parallel at intervals of the width L2 by making the thickness t3 of the top portion 13 of the protrusion 12 larger than the thickness t2 of the substrate 11. Is possible. As described above, by using the magnetic recording medium substrate 10, it is possible to define the substrate interval, the parallel alignment of the substrate intervals, and the axis alignment between the substrates in the plurality of magnetic recording medium substrates 10 (magnetic recording media). It becomes possible. Further, the top portion 13 of the projection 12 and the bottom surface 14 of the recess are brought into contact with each other, and the side surface of the projection 12 and the inner surface of the recess are brought into contact with each other, whereby the torque due to the rotation of the spindle motor 8 is applied to each magnetic recording medium substrate 10 ( Magnetic recording medium).

  Further, by changing the thickness t3 of the top portion 13 of the protruding portion 12, the width L2 of the gap between the plurality of magnetic recording medium substrates 10 can be changed.

  In the second embodiment, the top portion 13 of the protrusion 12 is formed on a flat surface, and the bottom surface 14 of the recess is formed on a flat surface. This is an example, and it may not be formed on a flat surface as in the first embodiment. Moreover, the cross-sectional shape of the protrusion part 12 and the cross-sectional shape of a recessed part are circular. This is an example, and the cross-sectional shape may be a polygon as in the first embodiment.

  Further, since the plurality of magnetic recording medium substrates 10 can be stacked and fixed to the rotating shaft of the spindle motor by the protrusions 12 formed on each magnetic recording medium substrate 10, the magnetic recording medium substrate 10 There is no need to form a through hole in the center of the. Therefore, it is possible to prevent the occurrence of distortion due to punching.

  In the second embodiment, as an example, two magnetic recording medium substrates 10 (magnetic recording media) are stacked and fixed. As another example, three or more magnetic recording medium substrates 10 (magnetic recording media) may be stacked and fixed. In addition, as in the magnetic recording medium substrate 1 according to the first embodiment, various resins can be used for the magnetic recording medium substrate 10. Further, similarly to the magnetic recording medium substrate 1 according to the first embodiment, the magnetic recording medium substrate 10 is manufactured by a molding method such as an injection molding method using a mold having a shape corresponding to the substrate. Can do.

(Modification)
Next, a modification of the magnetic recording medium substrate according to the second embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view of a magnetic recording medium substrate according to a modification of the second embodiment of the present invention.

  As shown in FIG. 6B, the magnetic recording medium substrate 10A according to the modification is similar to the magnetic recording medium substrate 10 according to the second embodiment described above, and includes a disk-shaped substrate 11 and a substrate 11. The projection 12 is provided at the center of the projection. Further, the magnetic recording medium substrate 10 </ b> A has a recess 15 formed on the bottom surface 14 of the recess corresponding to the protrusion 12. The recess 15 formed in the bottom surface 14 is a space for storing a cut mark 17 generated in the process of manufacturing the magnetic recording medium substrate 10A.

  For example, when the magnetic recording medium substrate 10A is manufactured by injection molding, a resin is filled through a spool into a cavity space formed by a mold. When the resin is cured in this state, a portion corresponding to the spool remains in the substrate pattern. For example, as shown in FIG. 6A, a projection 16 corresponding to a spool is formed on the top portion 13 of the projection 12 in the substrate pattern 20 produced by injection molding. By cutting the protrusion 16, the magnetic recording medium substrate 10 </ b> A is manufactured. However, the cut portion 17 having a rough surface remains on the top portion 13 of the magnetic recording medium substrate 10A due to the cutting of the protrusions 16.

  If the cut mark remains on the top of the protrusion, when a plurality of magnetic recording medium substrates are stacked, the cut mark of one magnetic recording medium substrate is formed on the protrusion of the other magnetic recording medium substrate. There is a possibility that the plurality of magnetic recording medium substrates cannot be maintained in parallel by contacting the bottom surfaces of the corresponding recesses.

  Therefore, in the magnetic recording medium substrate 10A according to the modified example, a recess 15 is formed on the bottom surface 14 of the recess corresponding to the position of the cut mark 17. The width of the recess 15 is made wider than the width of the cut mark 17 (the width of the protrusion 16 corresponding to the spool). Further, the depth of the recess 15 is made deeper than the height of the cut mark 17. In other words, the protrusion 16 is cut such that the height of the cut mark 17 is lower than the depth of the recess 15.

  Then, as shown in FIG. 6C, when a plurality of magnetic recording medium substrates 10A (magnetic recording media) are stacked, the magnetic recording medium substrates 10A remain on the top portion 13 of the protrusion 12 provided on one magnetic recording medium substrate 10A. The cut mark 17 is stored in a recess 15 formed on the bottom surface 14 of the recess of the other magnetic recording medium substrate 10A. That is, the recess 15 has a function of escaping the cut mark 17. As a result, the top portion 13 of the protrusion 12 can be brought into contact with the bottom surface 14, and the plurality of magnetic recording medium substrates 10 </ b> A can be kept in parallel.

  In the modification, as an example, two magnetic recording medium substrates 10A (magnetic recording medium) are stacked and fixed. As another example, three or more magnetic recording medium substrates 10A (magnetic recording media) may be stacked and fixed. In addition, as in the magnetic recording medium substrate 1 according to the first embodiment, various resins can be used for the magnetic recording medium substrate 10A. Further, similarly to the magnetic recording medium substrate 1 according to the first embodiment, the magnetic recording medium substrate 10A is manufactured by a molding method such as an injection molding method by using a mold having a shape corresponding to the substrate. be able to.

[Third Embodiment]
Next, a magnetic recording medium substrate according to a third embodiment of the invention will be described with reference to FIGS. FIG. 7 is a perspective view of a magnetic recording medium substrate according to the third embodiment of the present invention. FIG. 8 is a cross-sectional view of the magnetic recording medium substrate according to the third embodiment of the present invention, and is a cross-sectional view taken along the line VIII-VIII of FIG.

  The magnetic recording medium substrate 30 according to the third embodiment includes a disk-shaped substrate 31 having a flat surface and a protrusion 32 provided at the center of the substrate 31. Then, by forming a magnetic film on the surface of the magnetic recording medium substrate 30, a magnetic recording medium used in the magnetic disk device is manufactured.

  The protrusion 32 is provided on one surface of the substrate 31 and protrudes in the thickness direction of the substrate 31. The protrusion 32 has, for example, a circular shape in cross section parallel to the substrate 31. The diameter of the cross section of the protrusion 32 gradually decreases toward the top 33 of the protrusion 32. The protrusion 32 has a top 33 at the tip. That is, the side surface of the protrusion 32 is a slope formed obliquely with respect to the thickness direction of the magnetic recording medium substrate 30. The side surface of the protrusion 3 may be linear or curved. Further, the top 33 of the protrusion 32 is a flat surface. A pin 34 protruding in the thickness direction of the magnetic recording medium substrate 30 is provided on the top 33 of the protrusion 32. The pin 34 is provided at a position separated from the center of the substrate 31 by a predetermined distance. The pin 34 has, for example, a cylindrical shape. The pin 34 corresponds to an example of the “fitting part” or “fitted part” of the present invention.

  In the magnetic recording medium substrate 30, a recess is formed on the surface opposite to the surface from which the protrusion 32 protrudes in the direction in which the protrusion 32 protrudes. That is, the magnetic recording medium substrate 30 has a shape in which the center is recessed from one surface toward the opposite surface. This recess has a circular cross-sectional shape parallel to the substrate 31, for example. The concave portion formed in the magnetic recording medium substrate 30 has a maximum diameter on the surface of the magnetic recording medium substrate 30 and gradually decreases in the depth direction. That is, the inner surface of the recess is a slope formed obliquely with respect to the thickness direction of the magnetic recording medium substrate 30. The inner surface of the recess may be linear or curved.

  Further, the bottom surface 35 of the concave portion (the surface on the side opposite to the top portion 33 of the protruding portion 32) is a flat surface. A recess 36 into which a pin 34 formed on the top 33 of the protrusion 32 is fitted is formed on the bottom surface 35 of the recess. In the third embodiment, a recess 36 is formed at a position corresponding to the position of the pin 34 provided on the top 33 of the protrusion 32. That is, the recess 36 is provided at the same distance from the center of the substrate 31 as the pin 34, and the position of the pin 34 provided on the top 33 of the protrusion 32 and the recess 36 formed on the bottom 35 of the recess. The position is consistent. The recess 36 has a cylindrical shape. The diameter of the recess 36 substantially matches the diameter of the pin 34, and the depth of the recess 36 is greater than the height of the pin 34. The recess 36 corresponds to an example of the “fitted part” or “fitting part” of the present invention.

  The thickness of the substrate 31 is a constant thickness t2. Moreover, the thickness of the top 33 of the protrusion 32 is a constant thickness t3. The thickness t3 of the top 33 of the protrusion 32 is thicker than the thickness t2 of the substrate 31. That is, the relationship of thickness t3> thickness t2 is established between the thickness t2 of the substrate 31 and the thickness t3 of the top 33.

  Further, both surfaces of the magnetic recording medium substrate 30 are kept parallel. For example, the inclination of the side surface of the protrusion 32 and the inclination of the inner surface of the recess corresponding to the protrusion 32 are the same inclination.

  Further, the diameter d4 of the top 33 of the protrusion 32 is equal to the diameter d5 of the bottom surface 35 of the recess (the surface opposite to the top 33 of the protrusion 32). In other words, the diameter d4 of the top portion 33 of the protrusion 32 and the diameter d5 of the bottom surface 35 of the recess satisfy the relationship of diameter d4 = diameter d5. Further, the diameter d6 of the recess in the opening is larger than the diameter d4 of the top 33 of the protrusion 32 and the diameter d5 of the bottom surface 35 of the recess. In other words, the diameter d4 of the top 33 of the protrusion 32, the diameter d5 of the bottom surface 35 of the recess, and the diameter d6 of the recess in the opening satisfy the relationship of diameter d4 = diameter d5 <diameter d6.

  A magnetic recording medium is manufactured by forming a magnetic film on the surface of the timing recording medium substrate 30 by a film forming method such as sputtering.

  As described above, the magnetic disk device according to the embodiment of the present invention includes a plurality of time recording media stacked. Here, a magnetic disk device provided with the magnetic recording medium substrate 30 overlaid will be described with reference to FIG. FIG. 9 is a sectional view showing a state in which the magnetic recording medium substrates according to the third embodiment of the present invention are stacked. In the magnetic disk device, a plurality of magnetic recording media each having a magnetic film formed on the surface of the magnetic recording medium substrate 30 are stacked. Here, for ease of explanation, FIG. 9 shows a state in which the magnetic recording medium substrates 30 are stacked.

  As shown in FIG. 9A, a plurality of magnetic recording medium substrates 30 having the same shape are stacked. That is, the protrusions 32 of the magnetic recording medium substrate 30 are fitted into the recesses corresponding to the protrusions 32 of the other magnetic recording medium substrate 30 so that the plurality of magnetic recording medium substrates 30 are overlapped. Here, as an example, two magnetic recording medium substrates 30 are stacked. A stack of a plurality of magnetic recording media (magnetic recording medium substrate 30) corresponds to an example of the “magnetic recording portion” of the present invention.

  Of the plurality of stacked magnetic recording medium substrates 30, the pin 34 provided on the top 33 of the uppermost magnetic recording medium substrate 30 is cut. Alternatively, the magnetic recording medium substrate 30 without the pins 34 is manufactured, and the magnetic recording medium substrate 30 is placed on the top of the plurality of magnetic recording medium substrates 30. In the example shown in FIG. 9A, no pin 34 is provided on the magnetic recording medium substrate 30 installed on the upper part of the two magnetic recording medium substrates 30. As described above, the top 33 of the protrusion 32 of the magnetic recording medium substrate 30 installed at the top is formed into a flat surface, and the top 33 is pressed from above, so that a plurality of magnetic recording medium substrates 30 (magnetic The recording medium) is fixed with respect to the rotation shaft of the spindle motor 8.

  By fitting the protrusion 32 of the magnetic recording medium substrate 30 into the recess corresponding to the protrusion 32 of the other magnetic recording medium substrate 30, the pin 34 provided on the top of the protrusion 32 is The magnetic recording medium substrate 30 is fitted into a recess 36 formed on the bottom surface 35 of the recess. Further, the top 33 of the protrusion 32 of one magnetic recording medium substrate 30 is in contact with the bottom surface 35 of the recess corresponding to the protrusion 32 of the other magnetic recording medium substrate 30. Further, the side surface of the protrusion 32 of one magnetic recording medium substrate 30 is in contact with the inner surface of the recess corresponding to the protrusion 32 of the other magnetic recording medium substrate 30. As a result, the plurality of magnetic recording medium substrates 30 are overlapped and fixed. The diameter d4 of the top 33 of the protrusion 32 is equal to the diameter d5 of the bottom 35 of the recess corresponding to the protrusion 32, and the depth of the recess 36 formed on the bottom 35 is provided at the top 33 of the protrusion 32. Since the height of the pin 34 is deeper, the top 33 of the protrusion 32 provided on one magnetic recording medium substrate 30 is the bottom surface 35 of the recess corresponding to the protrusion 32 of the other magnetic recording medium substrate 30. To touch. Accordingly, there is no gap between the two magnetic recording medium substrates 30 at the center of the magnetic recording medium substrate 30.

  On the other hand, since the thickness t3 of the top 33 of the protrusion 32 is thicker than the thickness t2 of the substrate 31, a gap is generated between the two magnetic recording medium substrates 30 in the substrate 31. The width L2 of this gap corresponds to the difference between the thickness t3 of the top 33 of the protrusion 32 and the thickness t2 of the substrate 31. With this configuration, it is possible to change the width L2 of the gap between the two magnetic recording medium substrates 30 by changing the thickness t3 of the top 33 of the protrusion 32.

  Then, as shown in FIG. 9B, a hub 40 connected to the spindle motor 8 is fitted into a recess corresponding to the protrusion 32 of one of the magnetic recording medium substrates 30 (magnetic recording medium), thereby magnetically. By pressing the magnetic recording medium substrate 30 from the upper surface of the recording medium substrate 30 (magnetic recording medium), the two magnetic recording medium substrates 30 (magnetic recording medium) are fixed to the rotation axis of the spindle motor 8. . The hub 40 has a cylindrical shape, and the distal end portion 41 of the hub 40 gradually decreases in diameter toward the distal end of the hub 40. Furthermore, a pin 42 that fits into a recess 36 formed in the magnetic recording medium substrate 30 is provided at the tip 41 of the hub 40. By fitting the hub 40 into the concave portion of the magnetic recording medium substrate 30, the pin 42 provided at the distal end portion 41 of the hub 40 is fitted into the concave portion 36 formed in the magnetic recording medium substrate 30. The front end portion 41 of 40 is in contact with the bottom surface 25 of the concave portion of the magnetic recording medium substrate 30 and the inner surface of the concave portion. In this state, the magnetic recording medium substrate 30 is pressed from the upper surface of the magnetic recording medium substrate 30 to fix the two magnetic recording medium substrates 30 (magnetic recording medium) to the rotation shaft of the spindle motor 8. .

  By transmitting torque generated by the rotation of the spindle motor 8 to the magnetic recording medium substrate 30 (magnetic recording medium), the magnetic recording medium substrate 30 (magnetic recording medium) is rotationally driven. In the plurality of magnetic recording medium substrates 30 (magnetic recording media), the top 33 of the protrusion 32 is in contact with the bottom surface 35 of the recess, and the side surface of the protrusion 32 is in contact with the inner surface of the recess. By this contact, torque generated by the rotation of the spindle motor 8 is transmitted to each magnetic recording medium substrate 30.

  Furthermore, in the third embodiment, the pin 34 provided on the top 33 of the protrusion 32 of one magnetic recording medium substrate 30 is the bottom surface of the recess corresponding to the protrusion 32 of the other magnetic recording medium substrate 30. Also by fitting into the recess 36 formed in 35, it is possible to transmit the torque generated by the rotation of the spindle motor 8 to each magnetic recording medium substrate 30. Further, the projections 42 provided at the tip 41 of the hub 40 are fitted into the recesses 36 formed on the bottom surface 35 of the magnetic recording medium substrate 30, so that the torque generated by the rotation of the spindle motor 8 can be reduced to each magnetic field. Transmission to the recording medium substrate 30 is possible.

  Then, magnetic recording of data or the like is performed on the magnetic film on the surface of the magnetic recording medium by a magnetic head (not shown). In addition, data recorded on the track of the magnetic film is reproduced by the magnetic head.

  According to the magnetic recording medium substrate 30 according to the third embodiment, similarly to the magnetic recording medium substrate 20 according to the second embodiment, a plurality of layers are stacked and fixed to the rotation shaft of the spindle motor without providing a spacer. It becomes possible. In addition, a plurality of magnetic recording medium substrates 30 (magnetic recording media) can be held in parallel at intervals of the width L2, and the plurality of magnetic recording medium substrates 30 (magnetic recording media) can be aligned. . Furthermore, since it is not necessary to form a through hole at the center of the magnetic recording medium substrate 30, it is possible to prevent the occurrence of distortion due to punching. Furthermore, according to the magnetic recording medium substrate 30 according to the third embodiment, the pin 34 provided on the top 33 of the protrusion 32 and the recess 36 formed on the bottom surface 35 of the magnetic recording medium substrate 30 are fitted. As a result, the torque generated by the rotation of the spindle motor 8 can be transmitted to each magnetic recording medium substrate 30 (magnetic recording medium).

  In the third embodiment, the top 33 of the protrusion 32 is formed on a flat surface, and the bottom surface 35 of the recess is formed on a flat surface. This is an example, and it may not be formed on a flat surface as in the first embodiment. Moreover, the cross-sectional shape of the protrusion part 32 and the cross-sectional shape of a recessed part are circular. This is an example, and the cross-sectional shape may be a polygon as in the first embodiment.

  In the third embodiment, as an example, one pin 34 is provided on the top 33 of the protrusion 32, and one recess 36 is provided on the bottom surface 35. As another example, a plurality of pins 34 may be provided on the top 33 of the protrusion 32 and the same number of recesses 36 as the pins 34 may be provided on the bottom surface 35. By providing the plurality of pins 34 and the recesses 36 in this way, torque due to the rotation of the spindle motor 8 is easily transmitted to each magnetic recording medium substrate 30 (magnetic recording medium). Moreover, the shape of the pin 34 and the recessed part 36 may be shapes other than a cylinder. For example, the shape of the pin 34 and the recess 36 may be a prism.

  Alternatively, a continuous uneven shape may be formed along the circumference of the top 33 of the protrusion 32, and a continuous uneven shape corresponding to the uneven shape may be formed along the circumference of the bottom surface 35. For example, a gear-like uneven shape is formed along the circumference of the top portion 33 and the circumference of the bottom surface 35. Thus, by providing the gear-shaped uneven shape and meshing each magnetic recording medium substrate 30 (magnetic recording medium), the torque due to the rotation of the spindle motor 8 causes each magnetic recording medium substrate 30 (magnetic recording medium). Easier to communicate.

  Further, a recess may be formed on the top 33 of the protrusion 32 and a pin may be provided on the bottom 35. Even in such a configuration, when a plurality of magnetic recording medium substrates 30 (magnetic recording media) are stacked, the pin and the recess are fitted, whereby the torque due to the rotation of the spindle motor 8 is applied to each magnetic recording medium. This facilitates transmission to the substrate 30 (magnetic recording medium).

  In the third embodiment, as an example, two magnetic recording medium substrates 30 (magnetic recording media) are stacked and fixed. As another example, three or more magnetic recording medium substrates 30 (magnetic recording media) may be stacked and fixed. In addition, as in the magnetic recording medium substrate 1 according to the first embodiment, various resins can be used for the magnetic recording medium substrate 30. Further, similarly to the magnetic recording medium substrate 1 according to the first embodiment, the magnetic recording medium substrate 30 is manufactured by a molding method such as an injection molding method by using a mold having a shape corresponding to the substrate. be able to.

[Modification]
Next, a modification of the magnetic recording medium substrate according to the third embodiment will be described.

(Modification 1)
A magnetic recording medium substrate according to Modification 1 of the third embodiment will be described with reference to FIG. FIG. 10 is a cross-sectional view of a magnetic recording medium substrate according to Modification 1 of the third embodiment of the present invention.

  As shown in FIG. 10B, the magnetic recording medium substrate 30A according to the first modification example is similar to the magnetic recording medium substrate 30 according to the third embodiment described above. And a protruding portion 32 provided at the center of 31. A pin 34 is provided on the top 33 of the protrusion 32, and a recess 36 into which the pin 34 is fitted is formed on the bottom surface 35 of the recess corresponding to the protrusion 32. Further, in the magnetic recording medium substrate 10 </ b> A, a concave portion 37 different from the concave portion 36 is formed on the bottom surface 35 of the concave portion corresponding to the protruding portion 32. The recess 36 formed in the bottom surface 35 is a space for storing a cut mark 39 generated in the process of manufacturing the magnetic recording medium substrate 30A.

  For example, when the magnetic recording medium substrate 30A is manufactured by injection molding, a resin is filled through a spool into a cavity space formed by a mold. When the resin is cured in this state, a portion corresponding to the spool remains in the substrate pattern. For example, as shown in FIG. 10A, a substrate prototype 50 manufactured by injection molding has a protrusion 38 corresponding to a spool on the top 33 of the protrusion 32. By cutting the projection 38, the magnetic recording medium substrate 30A is manufactured. However, the cut marks 39 having a rough surface remain on the top 33 of the magnetic recording medium substrate 30A due to the cutting of the protrusions 38.

  Therefore, in the magnetic recording medium substrate 30 </ b> A according to the first modification, a concave portion 37 is formed on the bottom surface 35 of the concave portion corresponding to the position of the cut mark 39. The width of the recess 37 is made wider than the width of the cut mark 39 (the width of the projection 38 corresponding to the spool). Further, the depth of the concave portion 37 is made deeper than the height of the cut mark 39. In other words, the protrusion 38 is cut so that the height of the cut mark 39 is lower than the depth of the recess 37.

  As shown in FIG. 10C, when a plurality of magnetic recording medium substrates 30A (magnetic recording media) are stacked, the magnetic recording medium substrates 30A remain on the tops 33 of the protrusions 32 provided on one magnetic recording medium substrate 30A. The cut mark 39 is stored in a recess 37 formed on the bottom surface 35 of the recess of the other magnetic recording medium substrate 30A. As a result, the top 33 of the protrusion 32 can be brought into contact with the bottom 35, and the plurality of magnetic recording medium substrates 30A can be kept parallel.

  In Modification 1, as an example, two magnetic recording medium substrates 30A (magnetic recording medium) are stacked and fixed. As another example, three or more magnetic recording medium substrates 30A (magnetic recording media) may be stacked and fixed. In addition, as in the magnetic recording medium substrate 1 according to the first embodiment, various resins can be used for the magnetic recording medium substrate 30A. Further, similarly to the magnetic recording medium substrate 1 according to the first embodiment, the magnetic recording medium substrate 30A is manufactured by a molding method such as an injection molding method by using a mold having a shape corresponding to the substrate. be able to.

(Modification 2)
Next, a magnetic recording medium substrate according to Modification 2 of the third embodiment will be described with reference to FIGS. FIG. 11 is a cross-sectional view of a magnetic recording medium substrate according to Modification 2 of the third embodiment of the present invention. FIG. 12 is a top view of a magnetic recording medium substrate according to Modification 2 of the third embodiment of the present invention.

  Similar to the magnetic recording medium substrate 30 according to the third embodiment described above, the magnetic recording medium substrate 30 </ b> B according to Modification 2 includes a disk-shaped substrate 31 and a protrusion 32 provided at the center of the substrate 31. And have. A pin 34 is provided on the top 33 of the protrusion 32. Further, a concave portion 36A into which the pin 34 is fitted is formed on the bottom surface 35 of the concave portion (the surface on the side opposite to the top portion 33 of the protruding portion 32).

  In the second modification, the pin 34 provided on the top 33 of the protrusion 32 and the recess 36A formed on the bottom surface 35 are 180 degrees rotationally symmetric about the central axis O of the magnetic recording medium substrate 30B. Formed in position. That is, the pin 34 provided on the top 33 of the protrusion 32 and the recess 36A formed on the bottom surface 35 are provided on opposite sides of the central axis O, respectively.

  If the pin 34 and the concave portion are formed at the same position, the portion becomes thin and the strength of the substrate may be lowered. By forming the pins 34 and the recesses 36A at different positions as in the third modification, it is possible to prevent the substrate from becoming thin and to prevent a decrease in the strength of the substrate. In the third modification, the pin 34 and the concave portion 36A are provided at 180 ° rotationally symmetric positions. This arrangement example is an example, and the pins 34 and the recesses 36A may be provided at an angle other than 180 degrees.

  Then, the position of the pin 34 provided on one magnetic recording medium substrate 30B and the position of the concave portion 36A formed on the bottom surface 35 of the other magnetic recording medium substrate 30B are matched to each other to form a plurality of magnetic recording medium substrates. Stack 60. As a result, the pin 34 provided on the top 33 of the protrusion 32 is fitted into the recess 36 </ b> A formed on the bottom surface 35, and torque generated by the rotation of the spindle motor is transmitted to each magnetic recording medium substrate 30.

(Modification 3)
Next, a magnetic recording medium substrate according to Modification 3 of the third embodiment will be described with reference to FIG. FIG. 13 is a cross-sectional view of a magnetic recording medium substrate according to Modification 3 of the third embodiment of the present invention.

  As shown in FIG. 10A, the substrate prototype 50 according to the modification 1 has a protrusion 38 corresponding to a spool formed on the top 33 of the protrusion 32. This is because a spool for filling the cavity space formed by the mold with resin is formed on the top 33 side of the protrusion 32. A magnetic recording medium substrate may be manufactured by changing the position of the spool.

  For example, by forming a spool on the concave side corresponding to the protruding portion 32, a protruding portion 38A corresponding to the spool is formed on the bottom surface 35 of the concave portion corresponding to the protruding portion 32, for example, as in the substrate prototype 50A shown in FIG. You may do it. Then, the protrusion 38A is cut to produce a magnetic recording medium substrate.

1 is a perspective view of a magnetic recording medium substrate according to a first embodiment of the present invention. It is sectional drawing of the board | substrate for magnetic recording media which concerns on 1st Embodiment of this invention, and is II-II sectional drawing of FIG. It is sectional drawing of the board | substrate which shows the state which accumulated the board | substrate for magnetic recording media based on 1st Embodiment of this invention. It is sectional drawing of the board | substrate for magnetic recording media which concerns on 2nd Embodiment of this invention. It is sectional drawing of the board | substrate which shows the state which accumulated the board | substrate for magnetic recording media based on 2nd Embodiment of this invention. It is sectional drawing of the board | substrate for magnetic recording media based on the modification of 2nd Embodiment of this invention. It is a perspective view of the substrate for magnetic recording media concerning a 3rd embodiment of this invention. FIG. 8 is a cross-sectional view of a magnetic recording medium substrate according to a third embodiment of the present invention, which is a cross-sectional view taken along the line VIII-VIII in FIG. 7. It is sectional drawing of the board | substrate which shows the state which accumulated the board | substrate for magnetic recording media based on 3rd Embodiment of this invention. It is sectional drawing of the board | substrate for magnetic recording media which concerns on the modification 1 of 3rd Embodiment of this invention. It is sectional drawing of the board | substrate for magnetic recording media which concerns on the modification 2 of 3rd Embodiment of this invention. It is a top view of the board | substrate for magnetic recording media which concerns on the modification 2 of 3rd Embodiment of this invention. It is sectional drawing of the board | substrate for magnetic recording media which concerns on the modification 3 of 3rd Embodiment of this invention.

Explanation of symbols

1, 10, 10A, 30, 30A, 30B Magnetic recording medium substrate 2, 11, 31 Substrate 3, 12, 32 Protrusion 4, 13, 33 Top 5, 14, 35 Bottom 6, 40 Hub 7, 41 Tip 8 Spindle motor 15, 36, 36A, 37 Recessed part 17, 39 Cut mark 20, 50, 50A Substrate prototype 34, 42 pin

Claims (9)

A disk-shaped substrate having a flat surface;
A protrusion provided in the center of the substrate so as to protrude in the thickness direction of the substrate, the width gradually decreasing toward the tip, and a protrusion having a top at the tip;
On the surface opposite to the surface from which the protrusion protrudes, a recess is formed at a position corresponding to the protrusion, and the width gradually decreases in the depth direction.
Have
The inclination of the side surface of the protrusion is equal to the inclination of the inner surface of the recess,
A magnetic recording medium substrate, wherein the width of the top of the protrusion is narrower than the width of the opening of the recess and wider than the width of the bottom of the recess. A disk-shaped substrate having a flat surface;
A protrusion provided in the center of the substrate so as to protrude in the thickness direction of the substrate, the width gradually decreasing toward the tip, and a protrusion having a top at the tip;
On the surface opposite to the surface from which the protrusion protrudes, a recess is formed at a position corresponding to the protrusion, and the width gradually decreases in the depth direction.
Have
The inclination of the side surface of the protrusion is equal to the inclination of the inner surface of the recess,
The thickness of the tip of the protrusion is thicker than the thickness of the substrate,
A magnetic recording medium substrate, wherein the width of the top of the protrusion is narrower than the width of the opening of the recess and is substantially equal to the width of the bottom of the recess. At the top of the protrusion, a fitting portion is provided at a position away from the center of the substrate by a predetermined distance,
The magnetic recording medium substrate according to claim 2, wherein a fitted portion is provided at a position away from the center of the substrate by the predetermined distance on the bottom surface of the recess. The top of the protrusion has a flat circular shape,
The fitting portion has a continuous uneven shape and is provided along the circumference of the top portion of the protrusion,
The bottom surface of the recess has a flat circular shape,
The magnetic recording medium substrate according to claim 3, wherein the fitted portion has a continuous uneven shape and is provided along a circumference of the bottom surface.   5. The magnetic recording medium substrate according to claim 2, wherein another concave portion is formed on a bottom surface of the concave portion. A disk-shaped substrate having a flat surface, and a protrusion protruding in the thickness direction of the substrate at the center of the substrate, gradually narrowing toward the tip, and having a top at the tip; A concave portion that is formed at a position corresponding to the protruding portion on the opposite side of the surface from which the protruding portion protrudes and that gradually decreases in the depth direction, and the side surface of the protruding portion The magnetic film is formed on the surface of the substrate for the magnetic recording medium in which the inclination of the protrusion is equal to the inclination of the inner surface of the recess, and the width of the top of the protrusion is narrower than the opening of the recess and wider than the width of the bottom of the recess A magnetic recording medium formed by stacking a plurality of magnetic recording media by fitting the protrusions into the recesses of another magnetic recording medium,
A hub that fits into a recess of a magnetic recording medium provided at the bottom of the magnetic recording unit;
Driving means for rotationally driving the magnetic recording unit via the hub;
A magnetic head for recording or reproducing the magnetic recording medium;
A magnetic disk device comprising: A disk-shaped substrate having a flat surface, and a protrusion protruding in the thickness direction of the substrate at the center of the substrate, gradually narrowing toward the tip, and having a top at the tip; A concave portion that is formed at a position corresponding to the protruding portion on the opposite side of the surface from which the protruding portion protrudes and that gradually decreases in the depth direction, and the side surface of the protruding portion The inclination of the inner surface of the recess is equal, the thickness of the top of the projection is thicker than the thickness of the substrate, the width of the top of the projection is narrower than the width of the opening of the recess, A magnetic recording medium having a magnetic film formed on the surface of the magnetic recording medium substrate substantially equal to the width of the bottom surface of the magnetic recording medium is overlapped by fitting the protrusions into the recesses of the other magnetic recording medium. A magnetic recording unit,
A hub that fits into a recess of a magnetic recording medium provided at the bottom of the magnetic recording unit;
Driving means for rotationally driving the magnetic recording unit via the hub;
A magnetic head for recording or reproducing the magnetic recording medium;
A magnetic disk device comprising: At the top of the protrusion, a fitting portion is provided at a position away from the center of the substrate by a predetermined distance,
In the bottom surface of the recess, a fitted portion is provided at a position separated from the center of the substrate by the predetermined distance,
8. The magnetic disk apparatus according to claim 7, wherein the fitting portion and the fitted portion are fitted by fitting the protruding portion into a concave portion of another magnetic recording medium. The top of the protrusion has a flat circular shape,
The fitting portion has a continuous uneven shape and is provided along the circumference of the top portion of the protrusion,
The bottom surface of the recess has a flat circular shape,
9. The magnetic disk apparatus according to claim 8, wherein the fitted portion has a continuous uneven shape and is provided along a circumference of the bottom surface.

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