JP2009054252A - Substrate for magnetic recording medium, magnetic recording medium, and magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for a magnetic recording medium which facilitates connection between a head retreating section and a storage area in movement of a magnetic head in loading/unloading and to provide the magnetic recording medium using the substrate. <P>SOLUTION: An inside portion at a predetermined distance from a periphery edge 8 on at least one side face of a resin substrate of a disk shape having a through hole 4 at the center, has a shape to separate gradually toward the outside from a reference plane A which crosses a through hole at a face of direction orthogonal to a direction of thickness of the substrate. Namely, it becomes thick gradually toward the outside of the inside portion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium substrate used for a substrate of a magnetic disk recording apparatus, a magnetic recording medium using the substrate, and a magnetic recording apparatus using the same, and more particularly, a magnetic recording medium using a resin substrate. Related to the substrate

  Conventionally, an aluminum substrate or a glass substrate is used as a magnetic disk recording medium used in a computer or the like. A metal magnetic thin film is formed on the substrate, and information is recorded by magnetizing the metal magnetic thin film with a magnetic head (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

  For example, when using an aluminum substrate, the aluminum plate is press-molded into a disk shape, and then the surface is smoothed by applying high-precision grinding / polishing and cleaning processes, followed by plating. To form a nickel-phosphorus (Ni-P) alloy on the surface of the substrate, followed by polishing and texturing, and further forming a magnetic layer of Co-based alloy by sputtering to form a magnetic recording medium. Manufactured.

  When a glass substrate is used, a glass material is melted, and the molten glass is press-molded to produce a disk-shaped glass substrate. Then, the surface of the glass substrate is subjected to high-precision grinding / polishing processing and a cleaning process to smooth the surface, and then the surface is chemically strengthened by ion exchange with an alkali solvent molten salt, and a precision cleaning process. After that, texture processing is performed, and a magnetic layer of a Co-based alloy is formed by sputtering to produce a magnetic recording medium.

  By the way, an attempt has been made to adopt a resinous substrate such as a plastic substrate as the substrate for the magnetic recording medium. In this case, a magnetic recording medium is manufactured by forming a magnetic layer on a resinous substrate.

JP 2003-54965 A JP 2003-55001 A JP 2000-163740 A

  FIG. 8 is a diagram for explaining an L / UL (Load / Unload system) type magnetic recording apparatus. In the magnetic recording apparatus, when the disk 81 rotates at high speed, the filled air creates a gap between the magnetic head 82 that reads and writes magnetic data and the disk 81 that is coated with a magnetic material. Contact between the head 82 and the disk 81 is avoided, and deterioration of the recording area is reduced. On the other hand, when the rotation of the disk 81 is slow, no gap is created by the air, and the magnetic head 82 and the disk 81 come into contact with each other. Therefore, a magnetic recording apparatus has been proposed that employs an L / UL system in which the disk 81 is retracted to an inclined portion called a head retracting portion (ramp) 5 outside the storage area where the magnetic material is applied to the disk 81 during non-operation. In this method, a head assembly 83 having a magnetic head 82 near the tip is driven to the outside of the storage area, so that the magnetic head 82 rides on the head retracting portion 5 in a low rotation state at the time of starting and stopping. 81 is evacuated from above. As a result, the possibility of contact between the disk 81 and the magnetic head 82 is reduced, and high impact resistance is realized. The movement onto the head retracting unit 5 is such that the magnetic head is not actually in contact with the head retracting unit 5 and the tip protruding from the magnetic head 82 of the head assembly 83 is inclined to the head retracting unit 5. By contact, the magnetic head 82 is gradually lifted as it goes outward.

  However, in the conventional magnetic recording medium, the angle difference between the inclination of the head retracting portion and the surface of the disk is large. Therefore, when the magnetic head comes down from the ramp to the storage area (when loading), or the magnetic head retracts to the ramp. Connection (during unloading), the connection between the head retracting portion and the storage area in moving the magnetic head was not smooth. For this reason, the suspension arm that drives the head at the time of loading / unloading is twisted, and a large load is applied, which may cause a significant decrease in durability of the suspension mechanism.

  In this respect, it is difficult to adjust the angle of the substrate because it is difficult to process with a substrate using glass or aluminum, but it is easy to process with a substrate using resin, and the angle of the substrate is adjusted accurately. can do.

  The present invention has been made in view of such circumstances, and a substrate for a magnetic recording medium in which the connection between the head retracting portion and the storage area in the movement of the magnetic head during loading / unloading is smooth, and its An object of the present invention is to provide a magnetic recording medium using a substrate.

  In order to achieve the above object, a magnetic recording medium substrate according to claim 1 is an inner portion of a disk-like resinous substrate having a through hole in the center, at a predetermined distance from the outer peripheral end. However, it is characterized in that it has a shape that gradually separates outward from a reference plane that intersects the through hole in a plane perpendicular to the thickness direction of the substrate.

  According to a second aspect of the present invention, there is provided the magnetic recording medium substrate according to the first aspect, wherein the inner portion has a shape that gradually increases toward the outer side.

  A third aspect of the present invention is the magnetic recording medium substrate according to the first or second aspect, wherein the shape gradually moving away from the reference surface has a constant inclination. It is.

  A fourth aspect of the present invention is the magnetic recording medium substrate according to the third aspect, wherein an angle formed between the inclination of the inner portion and the reference plane is 0.2 to 5.0 degrees. It is a feature.

  A fifth aspect of the present invention is the magnetic recording medium substrate according to the first or second aspect, wherein the shape gradually separating from the reference surface is a curved surface. .

  A sixth aspect of the present invention is the magnetic recording medium substrate according to the fifth aspect, wherein an angle formed by a reference line and a tangent line in a direction perpendicular to the circumferential direction at the outer peripheral end portion is 0.2 degrees. It is ˜5.0 degrees.

  A seventh aspect of the present invention is the magnetic recording medium substrate according to any one of the first to sixth aspects, wherein a predetermined distance from the through hole of the resinous substrate is a flat portion, and the flat surface The outside of the part is the inside part.

  An eighth aspect of the invention is the magnetic recording medium substrate according to any one of the first to seventh aspects, wherein the shape is formed on both surfaces of the resinous substrate. It is what.

  The invention according to claim 9 is the magnetic recording medium substrate according to claim 1, wherein the thickness of the one surface and the other surface of the resinous substrate is constant. Is.

  The magnetic recording medium according to claim 10 includes a resin-based substrate having a disc-like shape and having a through hole in the center thereof, and a magnetic layer formed on at least one surface of the substrate, The inner portion of a predetermined distance from the outer peripheral edge of one surface has a shape that gradually separates outward from a reference surface that intersects the through hole in a direction perpendicular to the thickness direction of the substrate. It is what.

  The magnetic recording apparatus according to claim 11, wherein a substrate of a resinous group having a disc-like shape and having a through hole in the center, and an inner portion at a predetermined distance from an outer peripheral end of at least one surface of the substrate are A magnetic layer formed on the at least one surface, wherein the magnetic layer has a shape gradually moving outward from a reference surface intersecting with the through hole in a plane perpendicular to the thickness direction of the magnetic layer, and magnetic information And a head retracting part for retracting the magnetic head for reading and writing to the outside of the storage area when the rotation of the substrate is slow or stopped, and the head retracting part has an inclination away from the reference surface toward the outside. And the difference between the angle formed by the inclination of the substrate and the reference plane at the boundary between the substrate and the head retracting section and the angle formed by the head retracting section and the reference plane is 0.2 degrees to It is characterized by 5.0 degrees Than is.

  A magnetic recording medium substrate according to any one of claims 1 to 9, or a magnetic recording medium according to claim 10 using the substrate, wherein the magnetic recording medium has an inclination toward the outside or a curved surface. It has become. According to the magnetic recording apparatus of claim 11 using the magnetic recording medium substrate or the magnetic recording medium, the angle of the head retracting portion and the angle of inclination at the outer peripheral edge of the substrate (tangential angle) Including the difference)). As a result, when the magnetic head on the storage area moves to the retracting section, or when the magnetic head moves from the retracting section to the storage area, the connection between the storage area and the retracting section can be made smooth. .

[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 view of a magnetic recording medium substrate according to a first embodiment of the present invention as seen from the thickness direction. FIG. 2 is a cross-sectional view of the magnetic recording medium substrate according to the first embodiment of the present invention. FIG. 2 shows a cross section taken along the alternate long and short dash line in FIG.

  As shown in FIG. 1, the magnetic recording medium substrate 1 has a disk shape, and as shown in FIG. 2, a through hole 4 is formed in the center O of the substrate. The magnetic recording medium substrate 1 is made of a nonmagnetic material. In this embodiment, a case where a resin is used as an example of the nonmagnetic material will be described.

  Next, the material of the magnetic recording medium substrate 1 will be described. 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.

  For the magnetic recording medium substrate 1, for example, polycarbonate, polyetheretherketone resin (PEEK resin), cyclic polyolefin resin, methacrylstyrene resin (MS resin), polystyrene resin (PS resin), polyetherimide are used as the thermoplastic resin. 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. In addition, 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 polybenzoimidazole resin. Can be used. In addition, polyethylene naphthalate resin (PEN resin) or the like can be used.

  Furthermore, as the active ray 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 particularly preferred, 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. In addition, it is an example of resin used for the board | substrate 1 for magnetic recording media mentioned above, The board | substrate which concerns on this invention is not limited to these resin. Two or more types of resins may be mixed to form a resin substrate, or different components may be adjacent to each other as separate layers.

  The method for manufacturing the magnetic recording medium substrate 1 uses an injection molding method, a casting molding method, a sheet molding method, an injection compression molding method, or a mold having a shape corresponding to the shape of the magnetic recording medium substrate 1. It can be produced by a molding method such as a compression molding method. Further, the magnetic recording medium substrate 1 may be manufactured by cutting, punching, or press forming the formed substrate as necessary.

  Here, the reference plane A is a plane orthogonal to the thickness direction of the magnetic recording medium substrate 1 and is a plane intersecting the through hole 4.

  In the magnetic recording medium substrate 1, the front surface 2 and the back surface 3 on which the magnetic layer is formed have an inclination from the inner peripheral end portion 7 toward the outer peripheral end portion 8. In the present embodiment, the entire surface 2 and the back surface 3 correspond to the inner portion in the present invention. As a result, the front surface 2 and the back surface 3 gradually move away from the reference surface A from the inner peripheral edge 7 toward the outer peripheral edge 8. This also gradually increases the thickness of the magnetic recording medium substrate 1. In the present embodiment, both the front surface 2 and the back surface 3 are formed with a magnetic layer as a storage area, and magnetic information is read and written by the magnetic head on either the front surface 2 or the back surface 3. Provided. Since the front surface 2 and the back surface 3 have the same configuration having a target shape, the following description will be made with the configuration on the front surface 2 side.

  The angle formed by the surface 2 with the reference plane A is an angle θ. Further, the angle formed by the head retracting portion 5 and the reference surface is an angle φ (the head retracting portion 5 is also disposed on the back surface 3 side). This angle θ is preferably configured to be included in the range of 0.2 degrees or more and 5.0 degrees or less. Furthermore, it is preferable that the angle difference between the angle θ and the angle φ is an angle included in 3.0 degrees or less.

  After the resin-made magnetic recording medium substrate 1 is manufactured, a coating layer is formed on the entire surface of the magnetic recording medium substrate 1 by a film forming method such as plating. Thereafter, the coating layer is polished, and a magnetic layer is formed on the polished coating layer to obtain a magnetic recording medium. This magnetic recording medium is hereinafter referred to as a “disk”.

  Here, a magnetic layer is formed on the magnetic recording medium substrate 1 to obtain a magnetic recording medium. Since this magnetic layer is very thin, the operation of the head depends on the shape of the magnetic recording medium substrate 1.

  Further, the head assembly 83, the magnetic head 82, and the head retracting portion 5 are attached to the manufactured magnetic recording medium as shown in FIG.

  As described above, both the front surface 2 and the back surface 3 of the magnetic recording medium substrate 1 in this embodiment, the magnetic recording medium configured by the substrate, and the magnetic recording apparatus configured by the substrate are removed from the through holes 4. Since the magnetic head gradually moves away from the reference plane A as it moves toward the head, the magnetic head gradually moves away from the reference plane A along its inclination. At this time, the moving direction of the magnetic head is an angle θ at the reference plane A. It is a direction away from. When the magnetic head is retracted to the head retracting portion 5 when the rotation of the disk is stopped, the magnetic head moves on the surface 2 at an angle θ in a direction away from the reference plane, and then moves to the head retracting portion 5 to further reference at the angle φ. Move away from the surface. That is, the moving direction of the magnetic head changes from the angle θ to the angle φ at the connection point where the magnetic head moves from the disk to the head retracting portion 5. Since the angle difference between the angle θ and the angle φ is small, the movement of the magnetic head can be smoothly connected at this connection point. This is the same when the magnetic head moves from the head retracting portion 5 to the disk.

[Second Embodiment]
FIG. 3 is a cross-sectional view of a magnetic recording medium substrate according to a second embodiment of the present invention. The magnetic recording medium substrate 1A according to the present embodiment has a magnetic layer as a recording area formed on one surface (here, surface 2), and reading / writing is performed on the recording area by a magnetic head, and the other surface. There is no magnetic recording area on the back surface 3 (here, the back surface 3), and no magnetic head is disposed on the back surface 3 side.

  The magnetic recording medium substrate 1A has a disk shape. The magnetic recording medium substrate 1A also has a through hole 4 formed in the center O of the substrate, as in the first embodiment. The magnetic recording medium substrate 1A is made of a nonmagnetic material. In this embodiment, a case where a resin is used as an example of the nonmagnetic material will be described.

  Further, the reference plane A is a plane orthogonal to the thickness direction of the magnetic recording medium substrate 1 </ b> A and is a plane intersecting the through hole 4.

  In the magnetic recording medium substrate 1 </ b> A, the surface 2 on which the magnetic layer is formed has an inclination from the inner peripheral end 7 toward the outer peripheral end 8. In the present embodiment, the front surface of the surface 2 corresponds to the inner portion in the invention. As a result, the surface 2 gradually moves away from the reference plane A from the inner peripheral end 7 toward the outer peripheral end 8. This also gradually increases the thickness of the magnetic recording medium substrate 1A. Since the back surface 3 has no magnetic storage area, the back surface 3 is a surface that is not used for reading and writing magnetic information, and is configured flat without inclination.

  The angle formed by the surface 2 with the reference plane A is an angle θ. Further, the angle formed by the head retracting unit 5 with the reference surface is an angle φ. This angle θ is preferably configured to be included in the range of 0.2 degrees or more and 5.0 degrees or less. Further, it is preferable that the angle difference between the angle θ and the angle φ is set to an angle included in 3.0 degrees or less of the present invention.

  As described above, when the storage area exists only on one surface, if only one surface is gradually separated from the reference surface A toward the outside from the through hole 4, one surface The magnetic head only on the side also gradually moves away from the reference plane A along the inclination. At this time, the moving direction of the magnetic head is a direction away from the reference plane A at an angle θ. Further, the angle formed with the reference plane A in the head retracting portion 5 is φ. That is, the moving direction of the magnetic head changes from the angle θ to the angle φ at the connection point where the magnetic head moves from the disk to the head retracting portion 5. Since the angle difference between the angle θ and the angle φ is small, the movement of the magnetic head disposed only on one surface can be smoothly connected at this connection point. This is the same when the magnetic head moves from the head retracting portion 5 to the disk.

[Third Embodiment]
FIG. 4 is a sectional view of a magnetic recording medium substrate according to the third embodiment of the present invention. The magnetic recording medium substrate 1B according to the present embodiment has a configuration in which a magnetic layer as a storage area is formed on both the front surface 2 and the back surface 3, and a magnetic head is disposed on either surface. .

  The magnetic recording medium substrate 1B has a disk shape. As in the first embodiment, the magnetic recording medium substrate 1B also has a through hole 4 formed in the center O of the substrate. This magnetic recording medium substrate 1B is made of a nonmagnetic material. In this embodiment, a case where a resin is used as an example of the nonmagnetic material will be described.

  The reference plane A is a plane orthogonal to the thickness direction of the magnetic recording medium substrate 1 </ b> B and is a plane intersecting the through hole 4.

  The magnetic recording medium substrate 1B has a front surface 2 and a back surface 3 that are curved. In the present embodiment, the entire surface 2 and the back surface 3 correspond to the inner portion in the present invention. Each surface is configured to gradually move away from the reference surface A from the inner peripheral end 7 toward the outer peripheral end 8. As a result, the thickness of the magnetic recording medium substrate 1 </ b> B gradually increases from the inner peripheral end 7 toward the outer peripheral end 8. In this embodiment, both the front surface 2 and the back surface 3 have storage areas, and both the front surface 2 and the back surface 3 read and write magnetic information by the magnetic head. Since the front surface 2 and the back surface 3 have a target shape and the same configuration, the following description will be made with the configuration on the front surface 2 side.

  A tangent of the surface 2 in a direction orthogonal to the circumferential direction at the boundary between the surface 2 and the head retracting portion 5 is a tangent 6. And the angle which this tangent 6 makes with the reference plane A is angle (theta). Further, the angle formed by the head retracting unit 5 with the reference surface is an angle φ. This angle θ is preferably configured to be included in the range of 0.2 degrees or more and 5.0 degrees or less. Furthermore, it is preferable that the angle difference between the angle θ and the angle φ is an angle included in 3.0 degrees or less. In the present embodiment, the tangent 6 at the boundary between the surface 2 and the head retracting portion 5 is used in order to improve the accuracy of reducing the angle difference, but the portion where the head retracting portion 5 overlaps the surface 2 is as follows. Since it is small, the angle between the tangent at the outermost peripheral end 8 and the reference plane A and θ is substantially the same, and the angle between the tangent at the outermost peripheral end 8 and the reference plane A may be used.

  As described above, both the front surface 2 and the back surface 3 are formed by curved surfaces that gradually move away from the reference surface A as they go outward from the through holes 4. As a result, the magnetic head gradually moves away from the reference plane A along the curved surface. The moving direction of the magnetic head at the connection point between the head retracting portion 5 and the surface 2 is a direction away from the reference plane A at an angle θ. When the magnetic head retracts to the head retracting portion 5 when the rotation of the disk is stopped, the magnetic head moves in a direction away from the reference plane at an angle θ at the connection point, and then moves to the head retracting portion 5 and further moves to the reference surface at an angle φ. Move away from. That is, the moving direction of the magnetic head changes from the angle θ to the angle φ at the connection point where the magnetic head moves from the disk to the head retracting portion 5. Since the angle difference between the angle θ and the angle φ is not more than a predetermined value, the magnetic head can be smoothly connected at this connection point. Further, since the front surface 2 and the back surface 3 are formed with curved surfaces, the angle θ is made closer to the angle φ while keeping the smooth movement of the magnetic head on the recording surface as compared with the case where the front surface 2 and the back surface 3 are formed with a straight line. Is possible. This is the same when the magnetic head moves from the head retracting portion 5 to the disk.

[Fourth Embodiment]
FIG. 5 is a sectional view of a magnetic recording medium substrate according to a fourth embodiment of the present invention. The magnetic recording medium substrate 1C according to this embodiment has a magnetic layer as a recording area formed on one surface (here, surface 2), and reading / writing is performed on the recording area by a magnetic head, and the other surface. There is no magnetic recording area on the back surface 3 (here, the back surface 3), and no magnetic head is disposed on the back surface 3 side.

  The magnetic recording medium substrate 1C has a disk shape. The magnetic recording medium substrate 1C also has a through hole 4 formed in the center O of the substrate, as in the first embodiment. This magnetic recording medium substrate 1B is made of a nonmagnetic material. In this embodiment, a case where a resin is used as an example of the nonmagnetic material will be described.

  Further, the reference plane A is a plane orthogonal to the thickness direction of the magnetic recording medium substrate 1 </ b> C and is a plane intersecting the through hole 4.

  The surface 2 of the magnetic recording medium substrate 1C is a curved surface. In the present embodiment, the entire surface 2 corresponds to the inner portion in the present invention. And the surface 2 is comprised so that it may leave | separate from the reference plane A gradually toward the outer peripheral end part 8 from the inner peripheral end part 7. FIG. As a result, the thickness of the magnetic recording medium substrate 1 </ b> C gradually increases from the inner peripheral end 7 toward the outer peripheral end 8. Since the back surface 3 has no magnetic storage area, the back surface 3 is a surface that is not used for reading and writing the next information and is flat.

  A tangent of the surface 2 in a direction orthogonal to the circumferential direction at the boundary between the surface 2 and the head retracting portion 5 is a tangent 6. And the angle which this tangent 6 makes with the reference plane A is angle (theta). Further, the angle formed by the head retracting unit 5 with the reference surface is an angle φ. This angle θ is preferably configured to be included in the range of 0.2 degrees or more and 5.0 degrees or less. Furthermore, it is preferable that the angle difference between the angle θ and the angle φ is an angle included in 3.0 degrees or less.

  As described above, in the case where the storage area exists only on one surface, only one surface may be formed of a curved surface that gradually moves away from the reference surface A toward the outside from the through hole 4. As a result, the magnetic head gradually moves away from the reference plane A along the curved surface. Here, the moving direction of the magnetic head at the connection point between the head retracting portion 5 and the surface 2 is a direction away from the reference plane A at an angle θ. When the magnetic head retracts to the head retracting portion 5 when the rotation of the disk is stopped, the magnetic head moves in a direction away from the reference plane at an angle θ at the connection point, and then moves to the head retracting portion 5 and further moves to the reference surface at an angle φ. Move away from. That is, the moving direction of the magnetic head changes from the angle θ to the angle φ at the connection point where the magnetic head moves from the disk to the head retracting portion 5. Since the angle difference between the angle θ and the angle φ is small, the movement of the magnetic head can be smoothly connected at this connection point. Since the angle difference between the angle θ and the angle φ is small, the movement of the magnetic head disposed only on one surface can be smoothly connected at this connection point. This is the same when the magnetic head moves from the head retracting portion 5 to the disk.

[Fifth Embodiment]
FIG. 6 is a sectional view of a magnetic recording medium substrate according to the fifth embodiment of the present invention. The magnetic recording medium substrate 1D according to the present embodiment has a configuration in which a magnetic layer as a storage area is formed on both the front surface 2 and the back surface 3, and a magnetic head is disposed on either surface. .

  The magnetic recording medium substrate 1D has a disk shape. As in the first embodiment, the magnetic recording medium substrate 1D also has a through hole 4 formed in the center O of the substrate. The magnetic recording medium substrate 1D is made of a nonmagnetic material. In this embodiment, a case where a resin is used as an example of the nonmagnetic material will be described.

  Further, the reference plane A is a plane orthogonal to the thickness direction of the magnetic recording medium substrate 1 </ b> D and is a plane intersecting the through hole 4.

  The magnetic recording medium substrate 1D is configured such that both the front surface 2 and the back surface 3 have a flat surface with a distance L (predetermined distance in the present invention) from the inner peripheral edge 7, and outside the outer peripheral edge. 8 is formed with an inclination that gradually moves away from the reference plane A toward 8. In this embodiment, the outer portion of the region at a distance L from the inner peripheral edge 7 of the front surface 2 and the back surface 3 corresponds to the inner portion in the present invention. As a result, the thickness of the magnetic recording medium substrate 1D gradually increases in the vicinity of the outer peripheral end 8 (specifically, the portion outside the area L from the inner peripheral end 7 of the front surface 2 and the back surface 3). Become thicker. In this embodiment, both the front surface 2 and the back surface 3 have storage areas, and both the front surface 2 and the back surface 3 read and write magnetic information by the magnetic head, so both surfaces are inclined near the outer peripheral edge 8. It is the structure which has. Since the front surface 2 and the back surface 3 have a target shape and the same configuration, the following description will be made with the configuration on the front surface 2 side.

  The angle formed by the surface 2 with the reference plane A is an angle θ. Further, the angle that the head retracting portion 5 makes with the reference surface is an angle φ (the head retracting portion 5 is also disposed on the back surface 3 side). This angle θ is preferably configured to be included in the range of 0.2 degrees or more and 5.0 degrees or less. Further, it is preferable that the angle difference between the angle θ and the angle φ is an angle included within 3.0 degrees or less.

  As described above, both the front surface 2 and the back surface 3 have a flat surface from the through-hole 4 to the distance L, and are configured to have an inclination that gradually moves away from the reference surface A toward the outside. . As a result, the magnetic head gradually moves away from the reference plane A along the curved surface. The moving direction of the magnetic head at the connection point between the head retracting portion 5 and the surface 2 is a direction away from the reference plane A at an angle θ. When the magnetic head retracts to the head retracting portion 5 when the rotation of the disk is stopped, the magnetic head moves in a direction away from the reference plane at an angle θ at the connection point, and then moves to the head retracting portion 5 and further moves to the reference surface at an angle φ. Move away from. That is, the moving direction of the magnetic head changes from the angle θ to the angle φ at the connection point where the magnetic head moves from the disk to the head retracting portion 5. Since the angle difference between the angle θ and the angle φ is kept small, the movement of the magnetic head can be smoothly connected at this connection point. In addition, compared to the case where the entire surface has an inclination, the smoothness of the connection at the boundary between the inclined portion and the flat portion on the front surface 2 or the back surface 3 is reduced, but the reading and writing of the magnetic head is more stable at the flat portion. Can be made. This is the same when the magnetic head moves from the head retracting portion 5 to the disk.

  Further, in this embodiment, the linear inclination is described, but this may be a curved surface, and when there is a storage area only on one surface, the inclined or curved surface is provided only on one surface. And the other surface may be flat on the entire surface.

[Sixth Embodiment]
FIG. 7 is a sectional view of a magnetic recording medium substrate according to the sixth embodiment of the present invention. The magnetic recording medium substrate 1E according to this embodiment has a magnetic layer as a recording area formed on one surface (here, surface 2), and reading / writing is performed on the recording area by a magnetic head. There is no magnetic recording area on the back surface 3 (here, the back surface 3), and no magnetic head is disposed on the back surface 3 side.

  The magnetic recording medium substrate 1E has a disk shape. The magnetic recording medium substrate 1E also has a through hole 4 formed in the center O of the substrate, as in the first embodiment. The magnetic recording medium substrate 1E is made of a nonmagnetic material. In this embodiment, a case where a resin is used as an example of the nonmagnetic material will be described.

  The reference plane A is a plane orthogonal to the thickness direction of the magnetic recording medium substrate 1 </ b> E and is a plane intersecting the through hole 4.

  In the magnetic recording medium substrate 1E, the surface 2 on which the magnetic layer is formed has an inclination from the inner peripheral end 7 toward the outer peripheral end 8. In the present embodiment, the entire surface 2 hits the inner portion in the present invention. As a result, the surface 2 gradually moves away from the reference plane A from the inner peripheral end 7 toward the outer peripheral end 8. As a result, the thickness of the magnetic recording medium substrate 1E gradually increases from the inner peripheral end 7 toward the outer peripheral end 8. Since the back surface 3 has no magnetic storage area, it is a surface that is not used for reading and writing magnetic information, and the front surface 2 and the back surface 3 are configured with the same inclination as the front surface 2 so as to maintain a constant thickness.

  The angle formed by the surface 2 with the reference plane A is an angle θ. Further, the angle formed by the head retracting unit 5 with the reference surface is an angle φ. This angle θ is preferably configured to be included in the range of 0.2 degrees or more and 5.0 degrees or less. Furthermore, it is preferable that the angle difference between the angle θ and the angle φ is an angle included in 3.0 degrees or less.

  As described above, when the storage area exists only on one surface, if only one surface is gradually separated from the reference surface A toward the outside from the through hole 4, one surface The magnetic head which is only on the side also gradually moves away from the reference plane A along the inclination, and the moving direction of the magnetic head is a direction away from the reference plane A at an angle θ. Further, the angle formed with the reference plane A in the head retracting portion 5 is φ. That is, the moving direction of the magnetic head changes from the angle θ to the angle φ at the connection point where the magnetic head moves from the disk to the head retracting portion 5. Since the angle difference between the angle θ and the angle φ is small, the movement of the magnetic head disposed only on one surface can be smoothly connected at this connection point. Further, in this case, since the back surface 3 is formed with the same inclination as the front surface 2, the thickness of the magnetic recording medium substrate 1E becomes constant, and the deviation of the specific gravity of the disk can be reduced. This is the same when the magnetic head moves from the head retracting portion 5 to the disk.

  In the present embodiment, the case where the entire surface 2 is inclined has been described. However, even if the back surface 3 is formed of a curved surface opposite to the front surface 2 even though it is formed of a curved surface as in the fourth embodiment. Moreover, even if it is comprised by the surface which is flat to the middle like the surface 2 of Embodiment 5, and has an inclined part from the middle, the back surface 3 is similarly flat to the middle and is the same as the surface 2 from the middle What is necessary is just to be comprised so that it may have this inclination. Thus, when comprised by the surface which has an inclined part from the middle, the distance of an internal flat part has the preferable range of 2 mm or more and less than 10 mm. More preferably, it is in the range of 3 mm or more and less than 5 mm. Basically, when there is a portion where the angle changes in the recording portion, the read / write characteristics are hindered. Therefore, the flat portion is not the recording portion but the fixed area (clamp portion) of the inner diameter. Therefore, in order to increase the recording area, it is preferable that the fixed area is not large.

(Example)
Substrate tilt angle 3.5 degrees (for curved surfaces: tangential angle 3.5 degrees)
Head retracting part angle 4.5 degrees Substrate size: 48 mm
Inner diameter: 12mm
Inner circumference thickness: 0.60mm
Perimeter thickness: 0.75mm
Evaluation method: In a state of rotating at 4200 revolutions per minute, repeated loading and unloading are performed until a crash occurs.
Evaluation results
1st unit: Crash at 620,000 times 2nd unit: Crash at 500,000 times 3rd unit: Crash at 780,000 times

Results of comparative example (substrate thickness: 0.60 mm)
1st unit: Crash at 720,000 times 2nd unit: Crash at 46,000 times 3rd unit: Crash at 68,000 times

The figure which looked at the substrate for magnetic recording media concerning a 1st embodiment of this invention from the thickness direction Sectional drawing of the substrate for magnetic recording media concerning a 1st embodiment of this invention Sectional drawing of the substrate for magnetic recording media based on 2nd Embodiment of this invention Sectional drawing of the substrate for magnetic recording media based on 3rd Embodiment of this invention Sectional drawing of the substrate for magnetic recording media based on 4th Embodiment of this invention Sectional drawing of the substrate for magnetic recording media based on 5th Embodiment of this invention Sectional drawing of the substrate for magnetic recording media based on 6th Embodiment of this invention Diagram for explaining an L / UL magnetic recording apparatus

Explanation of symbols

1, 1A, 1B, 1C, 1D, 1E Magnetic recording medium substrate 2 Front surface 3 Rear surface 4 Through hole 5 Head retracting portion 6 Tangent line (at outer peripheral end portion) Inner peripheral end portion 8 Outer peripheral end portion

Claims (11)

From the reference plane where the inner portion of the disc-shaped resinous substrate having a through hole in the center at a predetermined distance from the outer peripheral end intersects with the through hole in a direction perpendicular to the thickness direction of the substrate. A substrate for a magnetic recording medium, characterized by having a shape that gradually separates toward the outside.   The magnetic recording medium substrate according to claim 1, wherein the inner portion has a shape that gradually becomes thicker toward the outside.   The magnetic recording medium substrate according to claim 1, wherein the shape gradually moving away from the reference surface has a constant inclination.   The magnetic recording medium substrate according to claim 3, wherein an angle formed between the inclination of the inner portion and a reference plane is 0.2 degrees to 5.0 degrees.   The magnetic recording medium substrate according to claim 1, wherein the shape gradually separating from the reference surface is a curved surface.   6. The magnetic recording medium substrate according to claim 5, wherein an angle formed between a tangent line in a direction orthogonal to the circumferential direction at the outer peripheral end portion and a reference plane is 0.2 degrees to 5.0 degrees.   7. The magnetic recording medium according to claim 1, wherein a predetermined distance from the through hole of the resinous substrate is a flat portion, and an outside of the flat portion is the inner portion. substrate.   8. The magnetic recording medium substrate according to claim 1, wherein the shape is formed on both surfaces of the resinous substrate.   2. The magnetic recording medium substrate according to claim 1, wherein the thickness of the one surface and the other surface of the resinous substrate is constant. A resin-based substrate having a disk-like shape and a through-hole in the center;
A magnetic layer formed on at least one surface of the substrate,
The inner part at a predetermined distance from the outer peripheral end of the at least one surface has a shape that gradually separates outward from the reference surface that intersects the through hole in a direction perpendicular to the thickness direction of the substrate. A magnetic recording medium characterized by the above. A resin-based substrate having a disk-like shape and a through-hole in the center;
A shape in which an inner portion of a predetermined distance from an outer peripheral end of at least one surface of the substrate gradually moves away from a reference surface intersecting a through-hole in a surface perpendicular to the thickness direction of the substrate. Have
A magnetic layer formed on the at least one surface;
A head retracting section for retracting a magnetic head for reading and writing magnetic information to the outside of the storage area when the rotation of the substrate is slow or stopped,
The head retracting portion has an inclination that is away from the reference surface toward the outside,
The difference between the angle formed by the inclination of the substrate and the reference plane at the boundary between the substrate and the head retracting section and the angle formed by the head retracting section and the reference plane is 0.2 to 5.0. A magnetic recording device characterized by