JP2007012142A - Magnetic transfer method and device thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic transfer method and device that can obtain uniform output over the whole surface of the disk to print. <P>SOLUTION: This method makes close contact of an initially DC magnetized magnetic recording medium 40 to be magnetically transferred and the master medium 48 having the magnetic pattern, then those recording medium to be magnetically transferred and master medium both in a close contact are moved relative to a magnetic field generator 30 to circumferentially apply magnetic fields. It transfers the magnetic pattern of the master medium to the magnetic recording medium to be magnetically transferred by making the applied magnetic field intensity between the 0.7 times maximum and the maximum almost over the whole surface of the magnetic recording medium to transfer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic transfer method and apparatus, and more particularly to a magnetic transfer method and apparatus suitable for transferring a magnetic information pattern such as format information from a master disk to a magnetic disk used in a hard disk device or the like.

  In recent years, magnetic disks (hard disks) used in hard disk drives, which have been rapidly spreading, are written with format information and address information before being installed in the drive after being delivered to the drive manufacturer by the magnetic disk manufacturer. It is common. Although this writing can be performed by a magnetic head, a method of batch transfer from a master disk in which these format information and address information are written is efficient and preferable.

  This magnetic transfer technology applies a magnetic field for transfer by arranging magnetic field generating means such as an electromagnet device or a permanent magnet device on one side or both sides in a state where a master disk and a disk to be transferred (slave disk) are in close contact with each other. The magnetic pattern corresponding to the information (for example, servo signal) of the master disk is transferred.

  Conventionally, various proposals have been made as this type of magnetic transfer technology (for example, Patent Document 1). The proposal of Patent Document 1 is such that the applied intensity of the transfer magnetic field is 0.6 to 1.3 times the coercivity of the slave disk. As a result, an effect of accurately transferring a high-quality pattern can be obtained.

The proposal of Patent Document 2 is to increase the applied magnetic field strength while relatively rotating the magnet device and the transfer disk. As a result, signal degradation does not occur and highly reliable transfer can be performed.
JP 2001-28127 A Japanese Patent Laid-Open No. 2002-237031

  However, in the conventional techniques such as Patent Documents 1 and 2, the relative magnetic field strength with respect to the medium coercive force on the disk surface of the magnetic field applied during magnetic transfer changes. There is a problem of reducing the N ratio.

  However, in Patent Document 1, there is no guideline for a range in which a change (variation) in magnetic field strength is practically acceptable, and the above problem cannot be solved.

  Further, in Patent Document 2, the influence of magnetic viscosity and the number of applied magnetic fields is not taken into consideration, and it is difficult to obtain a uniform output over the entire surface of the transferred disk.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a magnetic transfer method and apparatus capable of obtaining a uniform output over the entire surface of a transfer target disk.

  In order to achieve the above object, the present invention provides an adhesion step for bringing a magnetic recording medium to be transferred and a master medium having a magnetic pattern into close contact with each other, a magnetic field generating means, and a magnetic field generating means. Applying a magnetic field in the circumferential direction of the magnetic recording medium to be transferred and the master medium while moving the magnetic recording medium to be transferred and the master medium in close contact with each other, and applying them to each part of the medium The magnetic pattern of the master medium is transferred to the magnetic recording medium for transfer so that the maximum value of the magnetic field strength to be applied is in the range of the maximum magnetic field strength x 0.7 to the maximum magnetic field strength over substantially the entire surface of the magnetic recording medium for transfer. And a magnetic transfer step for transferring to the magnetic transfer method.

  In addition, for this purpose, the present invention is provided with a close contact means for bringing the magnetic recording medium to be transferred, which has been initially DC magnetized, and a master medium having a magnetic pattern, and a magnetic field generating means into close contact with the magnetic field generating means. Magnetic field applied to each part of the medium by applying a magnetic field in the circumferential direction of the transferred magnetic recording medium and the master medium while relatively moving the transferred magnetic recording medium and the master medium in a state The magnetic pattern of the master medium is transferred to the magnetic recording medium for transfer so that the maximum value of the intensity is in the range of maximum magnetic field strength × 0.7 to maximum magnetic field strength over substantially the entire surface of the magnetic recording medium for transfer. And a magnetic transfer means.

  According to the present invention, since the maximum value of the magnetic field strength applied to each part of the medium is controlled so as to be in the range of the maximum magnetic field strength × 0.7 to the maximum magnetic field strength over substantially the entire surface of the magnetic recording medium. In this case, there is little change in the magnetic field strength relative to the medium coercive force applied, and uniform magnetic transfer can be performed on substantially the entire surface.

  The present invention also relates to a magnetic recording medium to be transferred that depends on the application time of the magnetic field to which the coercive force is applied, and closely attaches the magnetic recording medium to be transferred that has been initially DC magnetized to the master medium having a magnetic pattern. The magnetic recording medium for transfer and the master medium are provided while providing an adhesion step, a magnetic field generation means, and relatively moving the magnetic recording medium for transfer and the master medium in close contact with the magnetic field generation means The magnetic pattern of the master medium is applied so that the coercive force is in the range of maximum coercive force × 0.7 to maximum coercive force over substantially the entire surface of the magnetic recording medium to be transferred. And a magnetic transfer step for transferring the image to the magnetic recording medium to be transferred.

  According to the present invention, the magnetic field is applied so that the coercive force is in the range of the maximum coercive force × 0.7 to the maximum coercive force over substantially the entire surface of the magnetic recording medium. The relative magnetic field strength is relatively small, and uniform magnetic transfer can be performed on substantially the entire surface.

  In the present invention, it is preferable to control the speed fluctuation of the relative movement speed for moving the transferred magnetic recording medium and the master medium in close contact with the magnetic field generating means within ± 15%.

  As described above, if the fluctuation of the relative moving speed is controlled within ± 15%, the change in the magnetic field strength relative to the coercive force of the medium is small on almost the entire surface of the magnetic recording medium, and uniform magnetic transfer can be performed on the almost entire surface. .

  In the present invention, the magnetic field generating means has substantially the same length as the radius of the transferred magnetic recording medium, and the applied magnetic field strength of the magnetic field generating means is changed from the inner peripheral side to the outer peripheral side of the transferred magnetic recording medium. It is preferable to increase it.

  Thus, if the applied magnetic field strength of the magnetic field generating means is increased from the inner circumference side to the outer circumference side of the magnetic recording medium, the change in the relative magnetic field strength with respect to the medium coercive force is small over almost the entire surface of the magnetic recording medium. Uniform magnetic transfer can be performed on almost the entire surface.

  Further, in the present invention, the magnetic field generating means has a length shorter than the radius of the magnetic recording medium, and the applied magnetic field strength of the magnetic field generating means is moved while moving the magnetic field generating means in the radial direction of the magnetic recording medium for transfer. Is preferably increased from the inner circumference side toward the outer circumference side of the magnetic recording medium for transfer.

  In this way, if the applied magnetic field strength is increased from the inner circumference side to the outer circumference side of the magnetic recording medium while moving the magnetic field generating means in the radial direction of the magnetic recording medium, the medium is maintained on almost the entire surface of the magnetic recording medium. There is little change in the magnetic field strength relative to the magnetic force, and uniform magnetic transfer can be performed on substantially the entire surface.

  Further, in the present invention, the magnetic field generating means has a length shorter than the radius of the magnetic recording medium, the magnetic field generating means is moved in the radial direction of the magnetic recording medium for transfer, and the magnetic field generating means and the transferred object are transferred. It is preferable that the relative rotational speed between the magnetic recording medium for recording and the master medium is decreased from the inner circumference side to the outer circumference side of the magnetic recording medium for transfer.

  In this way, the magnetic field generating means is moved in the radial direction of the magnetic recording medium, and the relative rotational speed (relative rotational speed) between the magnetic field generating means and the magnetic recording medium is decreased from the inner circumference side toward the outer circumference side. Thus, there is little change in the magnetic field strength relative to the coercive force of the magnetic recording medium over the entire surface, and uniform magnetic transfer can be performed over the entire surface.

  In the present invention, it is preferable that the number of times the magnetic field is applied in the circumferential direction of the magnetic recording medium to be transferred and the master medium is the same as the number of times in each part of the surface of the magnetic recording medium to be transferred. .

  As described above, if the number of times of applying the magnetic field in the circumferential direction of the magnetic recording medium is the same number in each portion in the plane, the change in the magnetization of the medium is small over almost the entire surface of the magnetic recording medium, and the magnetic field is uniform over the entire surface. Transcription is possible.

  In the present invention, it is preferable that the number of times the magnetic field is applied in the circumferential direction of the magnetic recording medium for transfer and the master medium is set once in each portion in the plane of the magnetic recording medium for transfer. .

  In this way, if the number of times the magnetic field is applied in the circumferential direction of the magnetic recording medium is set to once in each part of the surface, the change in the magnetization of the medium is small over the substantially entire surface of the magnetic recording medium, and the magnetic field is uniform over the substantially entire surface. Transcription is possible.

  Further, in the present invention, a portion of the number of times of applying a magnetic field in the circumferential direction of the magnetic recording medium for transfer and the master medium that is not the same number of times in the plane of the magnetic recording medium for transfer is The angle is preferably less than 1 degree.

  As described above, if a portion that does not have the same number of times in the plane of the number of times of applying the magnetic field in the circumferential direction of the magnetic recording medium is set to be less than 1 degree in the circumferential direction, the magnetization of the medium is almost entirely on the magnetic recording medium. There is little change and uniform magnetic transfer can be performed on almost the entire surface.

  Further, in the present invention, during the magnetic transfer preparation stage in which the magnetic field intensity is increased to the intensity required for the magnetic transfer, or during the magnetic transfer end stage in which the magnetic field intensity is decreased from the intensity required for the magnetic transfer. The magnetic recording medium for transfer that is in close contact with the magnetic field generation means during the magnetic transfer is set so that the relative movement speed of the magnetic recording medium for transfer and the master medium in close contact with the magnetic field generation means of It is preferable that the relative moving speed with respect to the master medium is larger.

  When a magnetic field is applied, a process of moving the magnet closer (or moving away from it) if it is a permanent magnet, or increasing (decrease) the current value if it is an electromagnet is inevitably required. The magnetic field applied to the medium at that time is unsteady, and it is desirable to reduce the influence. As a method for realizing this, when the rotational speed at the time of increasing the applied magnetic field strength (in the case of a permanent magnet, the distance is reduced, and in the case of an electromagnet, the current value is increased) is increased. Since the coercive force of the medium is increased, the strength of the applied magnetic field is relatively lowered, and the effect of reducing the influence of the unsteady state magnetic field can be obtained.

  As described above, according to the present invention, there is little change in the magnetic field strength and medium magnetization relative to the medium coercive force applied during magnetic transfer, and uniform magnetic transfer can be performed over substantially the entire surface.

  Hereinafter, preferred embodiments of a magnetic transfer method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a main part of a magnetic transfer apparatus 10 according to the present invention. FIG. 2 is a plan view showing a method for applying a magnetic field for transfer.

  FIG. 3 is a diagram showing the basic steps of the magnetic transfer method. 3A shows a process in which a magnetic field is applied in one direction and the slave disk 40, which is a magnetic recording medium to be transferred, is initially DC magnetized. FIG. 3B shows a process in which the master disk 46, which is a master medium, and a slave. (C) shows the state after magnetic transfer, in which the magnetic field is applied in the opposite direction with the disk 40 in close contact. Each figure is a schematic diagram, and the dimensions of each part are shown in proportions different from actual ones.

  In the magnetic transfer apparatus 10 of FIG. 1, at the time of magnetic transfer, a slave surface (magnetic recording surface) of a slave disk (magnetic recording medium for transfer) 40 after initial DC magnetization described later shown in FIG. ) Is brought into contact with the information carrying surface of the master disk (master medium) 46 and can be brought into close contact with a predetermined pressing force. Then, with the slave disk 40 and the master disk 46 in close contact with each other, a magnetic field for transfer can be applied by the magnetic field generating means 30 to transfer and record a magnetic pattern such as a servo signal.

  The slave disk 40 is a disk-shaped magnetic recording medium such as a hard disk or a flexible disk having a magnetic recording layer formed on both sides or one side. Or the cleaning process (burnishing etc.) which removes adhering dust is given as needed. The slave disk 40 is preliminarily magnetized in advance. Details of this will be described later.

  As the slave disk 40, a disk-shaped magnetic recording medium such as a hard disk or a high-density flexible disk can be used. As the magnetic recording layer of the slave disk 40, a coating type magnetic recording layer, a plating type magnetic recording layer, or a metal thin film type magnetic recording layer can be adopted.

  As the magnetic material of the metal thin film type magnetic recording layer, Co, Co alloy (CoPtCr, CoCr, CoPtCrTa, CoPtCrNbTa, CoCrB, CoNi, etc.), Fe, Fe alloy (FeCo, FePt, FeCoNi) can be used. These are preferable because clear transfer can be performed because of high magnetic flux density and magnetic anisotropy in the same direction as the magnetic field application direction (in-plane direction for in-plane recording).

  In order to provide the necessary magnetic anisotropy under the magnetic material (on the support side), it is preferable to provide a nonmagnetic underlayer. For this underlayer, it is necessary to match the crystal structure and lattice constant to the magnetic layer. For that purpose, it is preferable to use Cr, CrTi, CoCr, CrTa, CrMo, NiAl, Ru or the like.

  The master disk 46 is formed in a disk shape, and a transfer information carrying surface on which a fine uneven pattern is formed on one surface of the substrate 47 by a magnetic layer 48 (see FIG. 3B) is formed. The surface is held by contact means (not shown). One side (transfer information carrying surface) of the master disk 46 is in close contact with the slave disk 40.

  When the substrate 47 is a ferromagnetic material mainly composed of Ni or the like, the magnetic transfer is possible only by the substrate 47 and the magnetic layer 48 may not be covered, but the magnetic layer 48 having good transfer characteristics is provided. Therefore, better magnetic transfer can be performed. When the substrate 47 is a nonmagnetic material, it is necessary to provide the magnetic layer 48. The magnetic layer 48 of the master disk 46 is preferably a soft magnetic layer having a coercive force Hc of 48 kA / m (≈600 Oe) or less.

  As the substrate 47 of the master disk 46, glass of various compositions such as nickel, silicon, quartz glass, aluminum, alloys, ceramics of various compositions, synthetic resins, and the like can be used. The uneven pattern on the surface of the substrate 47 can be formed by a photofabrication method, a stamper method using a master disk formed by a photofabrication method, or the like.

  Formation of the master in the stamper method can be performed, for example, as follows. A photoresist layer is formed on a glass plate (or quartz glass plate) having a smooth surface by spin coating or the like, and after pre-baking, the laser plate is rotated in response to a servo signal while rotating the glass plate ( Or a portion corresponding to each frame on the circumference of a predetermined pattern, for example, a pattern corresponding to a servo signal extending linearly in the radial direction from the center of rotation to each track. To expose.

  Thereafter, the photoresist layer is developed to obtain a glass master having a concavo-convex shape formed by the photoresist layer from which the exposed portion has been removed. Next, based on the concavo-convex pattern on the surface of the glass master, the surface is plated (electroformed) to form a predetermined thickness, thereby creating a Ni substrate having a positive concavo-convex pattern on the surface. Then, the substrate is peeled from the glass master.

  This substrate is used as a press master as it is, or a soft master layer, a protective film, etc. are coated on the concavo-convex pattern as necessary to form a press master.

  Alternatively, the glass master may be plated to create a second master by electroforming, and the second master may be further plated to create a reversing master having a negative uneven pattern by electroforming. . Furthermore, the second master is plated and electroformed, or a low-viscosity resin is pressed and cured to create a third master, and the third master is plated and electroformed. A substrate having a positive uneven pattern may be formed.

  As the material of the substrate, Ni or Ni alloy can be used as the metal. As a plating method for producing this substrate, various metal film forming methods including electroless plating, electroforming, sputtering, and ion plating can be applied.

  The depth of the concavo-convex pattern on the substrate surface (projection height) is preferably in the range of 80 to 800 nm, and more preferably in the range of 100 to 600 nm. In the case of a servo signal, the uneven pattern is formed long in the radial direction. In this case, for example, the length in the radial direction is preferably 0.05 to 20 μm, and the length in the circumferential direction is preferably 0.05 to 5 μm. It is preferable to select a pattern having a longer radial direction within this range as a pattern carrying servo signal information.

  The magnetic layer 48 (soft magnetic layer) is formed by depositing a magnetic material by a vacuum film forming means such as a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or the like. As the magnetic material of the magnetic layer, Co, Co alloy (CoNi, CoNiZr, CoNbTaZr, etc.), Fe, Fe alloy (FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, FeTaN), Ni, Ni alloy (NiFe) may be used. it can. In particular, FeCo and FeCoNi can be preferably used. The thickness of the magnetic layer is preferably in the range of 50 nm to 500 nm, and more preferably in the range of 100 nm to 400 nm.

  A protective film such as diamond-like carbon is preferably provided on the magnetic layer 48, and a lubricant layer may be further provided on the protective film. In this case, the protective film is preferably a diamond-like carbon film having a thickness of 5 to 30 nm and a lubricant layer. Further, an adhesion strengthening layer such as Si may be provided between the magnetic layer 48 and the protective film. The lubricant has an effect of improving the deterioration of durability such as the occurrence of scratches due to friction when correcting the deviation caused in the contact process with the slave disk 40.

  The master disk 46 may be formed by producing a resin substrate using the above-mentioned press master and providing a magnetic layer on the surface thereof. As the resin material of the resin substrate, acrylic resin such as polycarbonate and polymethyl methacrylate, vinyl chloride resin such as polyvinyl chloride and vinyl chloride copolymer, epoxy resin, amorphous polyolefin, and polyester can be used.

  Of these, polycarbonate is preferable from the viewpoints of moisture resistance, dimensional stability, and price. If there are burrs in the molded product, they are removed by burnishing or polishing. Alternatively, the master disk 46 may be formed on the press master by spin coating, bar coating, or the like using an ultraviolet curable resin, an electron beam curable resin, or the like. The height of the pattern protrusions on the resin substrate is preferably in the range of 50 to 1000 nm, and more preferably in the range of 100 to 500 nm.

  A magnetic layer 48 is coated on the fine pattern on the surface of the resin substrate to obtain a master disk 46. The magnetic layer 48 can be formed by depositing a magnetic material using a vacuum deposition method such as vacuum deposition, sputtering, or ion plating, or a deposition method such as plating.

  On the other hand, the photofabrication method, which is one of the methods for forming the master disk 46, is performed according to the following procedure. First, for example, a photoresist is applied to a smooth surface of a flat substrate, and a pattern corresponding to information is formed by exposure and development processing using a photomask corresponding to a servo signal pattern.

  Next, in the etching process, the substrate is etched according to the pattern to form a hole having a depth corresponding to the thickness of the magnetic layer 48. Next, a magnetic material is formed on the surface of the substrate with a thickness corresponding to the formed hole by a vacuum film formation method such as a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or the like.

  Next, the photoresist is removed by a lift-off method, and the surface is polished to remove any flash, and the surface is smoothed.

  As shown in FIG. 1, the magnetic transfer by the master disk 46 includes a case where the master disk 46 is brought into close contact with one side of the slave disk 40 and sequential transfer is performed on one side, and a case where the master disks 46 and 46 are respectively applied to both sides of the slave disk 40. May be used for simultaneous transfer on both sides. The master disk 46 is subjected to a cleaning process to remove the adhering dust as needed before being brought into close contact with the slave disk 40.

  The magnetic field generating means 30 for applying the transfer magnetic field includes electromagnet devices 34 and 34 each having a coil 33 wound around a core 32 having a gap 31 extending in the radial direction of the slave disk 40 and the master disk 46 held by the contact means. A transfer magnetic field is provided on both sides, and has a magnetic force line G (see FIGS. 2 and 3) parallel to the track direction in the same direction in the vertical direction.

  When a magnetic field is applied, a transfer magnetic field is applied by the magnetic field generating means 30 while rotating the slave disk 40 and the master disk 46 together so that the transfer information of the master disk 46 can be magnetically transferred and recorded on the slave surface of the slave disk 40. The rotating means is provided. In addition to this configuration, a configuration in which the magnetic field generation unit 30 is provided to be rotationally moved can be employed.

  The transfer magnetic field does not have any magnetic field strength exceeding the maximum value in the optimum transfer magnetic field strength range (0.6 to 1.3 times the coercive force Hc of the slave disk 40) in any of the track directions. There are at least one portion having a magnetic field strength within the range in one track direction, and the magnetic field strength in the opposite track direction is less than the minimum value of the optimum transfer magnetic field strength range at any track position. A magnetic field having a magnetic field strength distribution is generated in a part of the track direction.

  Unlike the configuration of FIG. 1, the magnetic field generation unit 30 may be configured to be disposed only on one side of the slave disk 40. In addition, as other configurations of the magnetic field generating unit 30, various configurations (1 to 3) can be listed below.

  1) Configuration in which the magnetic field generating means 30 (the length of the gap 31) is substantially the same as the radius of the slave disk 40, and the applied magnetic field strength of the magnetic field generating means 30 is increased from the inner peripheral side to the outer peripheral side of the slave disk 40. .

  In this way, if the applied magnetic field strength of the magnetic field generating means 30 is increased from the inner circumference side to the outer circumference side of the slave disk 40, the change in the relative magnetic field strength with respect to the medium coercive force on the substantially entire surface of the slave disk 40. There are few, and uniform magnetic transfer can be performed on substantially the entire surface.

  2) The magnetic field generating means 30 (the length of the gap 31) is shorter than the radius of the slave disk 40, and the applied magnetic field strength of the magnetic field generating means 30 is set to the slave while moving the magnetic field generating means 30 in the radial direction of the slave disk 40. A configuration in which the disk 40 is increased from the inner peripheral side toward the outer peripheral side.

  In this way, if the applied magnetic field strength is increased from the inner circumference side to the outer circumference side of the slave disk 40 while moving the magnetic field generating means 30 in the radial direction of the slave disk 40, the medium is almost entirely on the slave disk 40. There is little change in the magnetic field strength relative to the coercive force, and uniform magnetic transfer can be performed on substantially the entire surface.

  3) The magnetic field generating means 30 (the length of the gap 31) is made shorter than the radius of the slave disk 40, and the magnetic field generating means 30 is moved in the radial direction of the slave disk 40, and the magnetic field generating means 30 and the slave disk 40 A configuration in which the relative rotational speed is decreased from the inner circumference side to the outer circumference side of the slave disk 40.

  In this way, the magnetic field generating means 30 is moved in the radial direction of the slave disk 40, and the relative rotational speed (relative rotational speed) between the magnetic field generating means 30 and the slave disk 40 is decreased from the inner circumference side toward the outer circumference side. Thus, there is little change in the magnetic field intensity relative to the coercive force of the medium on the substantially entire surface of the slave disk 40, and uniform magnetic transfer can be performed on the substantially entire surface.

  As another configuration, an electromagnet device or a permanent magnet device that generates a transfer magnetic field as shown in FIGS. 4A to 4C may be arranged on both sides or one side of the slave disk 40.

  The magnetic field generation means 22 in FIG. 4A is configured such that both sides parallel to the slave surface of one electromagnet 90 (or permanent magnet) extending in the radial direction of the slave disk 40 are configured as opposite magnetic poles, and generates a magnetic field in the track direction. To do.

  In the magnetic field generating means 24 in FIG. 4B, the end faces of the two parallel electromagnets 92 and 93 (or permanent magnets) extending in the radial direction of the slave disk 40 at predetermined intervals are configured as opposite magnetic poles, and the track direction To generate a magnetic field.

  The magnetic field generating means 26 in FIG. 4C is configured such that two parallel end faces toward the slave surface of a permanent magnet 94 (or electromagnet) extending in the radial direction with a U-shaped cross section are configured as opposite magnetic poles, and generate a magnetic field in the track direction. To do.

  Next, a magnetic transfer method using the magnetic transfer apparatus 10 configured as described above will be described.

  First, in FIG. 3 described above showing the basic mode of magnetic transfer, as shown in FIG. 3A, an initial magnetic field Hi is applied to the slave disk 40 in one direction in the track direction to perform initial magnetization (DC demagnetization) in advance. Do. This initial magnetization is a magnetic field having at least one magnetic field strength portion of the slave disk 40 that is equal to or greater than the coercive force Hc in the track direction position. A magnetic field having a magnetic field strength distribution that is only in the direction and whose magnetic field strength in the reverse direction is less than the coercive force of the slave disk 40 at any track position is used. This magnetic field is generated in a part in the track direction, and the slave disk 40 or the magnetic field is rotated in the track direction, whereby initial magnetization (DC demagnetization) of all tracks is performed.

  After the initial magnetization of FIG. 3A, as shown in FIG. 3B, the magnetic layer 48 is formed on the fine uneven pattern of the slave surface (magnetic recording surface) of the slave disk 40 and the substrate 47 of the master disk 46. The coated information carrying surface is brought into close contact, and a magnetic field for transfer Hd is applied in the direction opposite to the initial magnetic field Hi in the track direction of the slave disk 40 to perform magnetic transfer.

  As a result, as shown in FIG. 3C, the slave surface (track) of the slave disk 40 corresponds to the formation pattern of the close-contact convexity and the concave space of the magnetic layer 48 on the information carrying surface of the master disk 46. A magnetization pattern is transferred and recorded.

  Even if the concave / convex pattern of the substrate 47 of the master disk 46 is a negative pattern having a concave / convex shape opposite to the positive pattern of FIG. 3, the direction of the initial magnetic field Hi and the direction of the transfer magnetic field Hd are opposite to this. By doing so, the same magnetization pattern can be transferred and recorded.

  What is important when performing this magnetic transfer is to control the applied magnetic field intensity to be in the range of maximum magnetic field intensity × 0.7 to maximum magnetic field intensity on substantially the entire surface of the slave disk 40. In this way, there is little change in the magnetic field strength relative to the medium coercive force applied during magnetic transfer, and uniform magnetic transfer can be performed over substantially the entire surface.

  What is important is that, in the case of the slave disk 40 that depends on the application time of the magnetic field to which the coercive force is applied, the coercive force is in the range of maximum coercive force × 0.7 to maximum coercive force on substantially the entire surface of the slave disk 40. Is to apply a magnetic field. In this way, there is little change in the magnetic field strength relative to the medium coercive force applied during magnetic transfer, and uniform magnetic transfer can be performed over substantially the entire surface.

  Further, when performing magnetic transfer, it is preferable to control the speed fluctuation of the relative moving speed between the slave disk 40 and the magnetic field generating means 30 within ± 15%. By controlling in this way, there is little change in the magnetic field strength relative to the medium coercive force applied during magnetic transfer, and uniform magnetic transfer can be performed on substantially the entire surface.

  Further, it is preferable that the number of times of applying the magnetic field in the circumferential direction of the slave disk 40 is the same number in each portion in the plane of the slave disk 40. In this way, there is little change in the magnetic field strength relative to the medium coercive force on substantially the entire surface of the slave disk 40, and uniform magnetic transfer can be performed on the substantially entire surface.

  Further, it is preferable that the number of times of applying the magnetic field in the circumferential direction of the slave disk 40 is once in each portion in the plane of the slave disk 40. In this way, there is little change in medium magnetization on the substantially entire surface of the slave disk 40, and uniform magnetic transfer can be performed on the substantially entire surface.

  Further, it is preferable that the portion of the number of times of applying the magnetic field in the circumferential direction of the slave disk 40 that is not the same number in the plane of the slave disk 40 is less than 1 degree in the circumferential direction. In this way, there is little change in medium magnetization on the substantially entire surface of the slave disk 40, and uniform magnetic transfer can be performed on the substantially entire surface.

  According to such magnetic transfer, there is little change in the magnetic field strength and medium magnetization relative to the applied medium coercive force, and uniform magnetic transfer is performed on almost the entire surface. Therefore, C of the reproduction signal of the transferred slave disk 40 The / N ratio becomes good.

The slave disk 40 can be suitably used by being incorporated in a magnetic recording device (hard disk drive). As the hard disk drive used for this, various known devices sold by each drive manufacturer may be used.
The embodiments of the magnetic transfer method and apparatus according to the present invention have been described above. However, the present invention is not limited to the above embodiments, and various aspects can be adopted.

  For example, in the above embodiment, magnetic transfer is performed to the slave disk 40 by the magnetic field generation means 30 while the slave disk 40 (also the closely attached master disk 46) is continuously rotated. It is also possible to adopt a configuration in which the magnetic field strength is reduced to a predetermined value after the magnetic field application of 1 or more in the circumferential direction is performed, and then the rotation of the slave disk 40 and the master disk 46 is stopped.

  As described above, if the magnetic field strength is gradually reduced to a predetermined value after one round of transfer in the circumferential direction and then the rotation is stopped, the influence of the transfer accuracy is very small, and the C / The N ratio becomes good.

[Making a master disk for magnetic transfer]
After reducing the pressure to 1.33 × 10 ⁻⁵ Pa (10 ⁻⁷ Torr) at room temperature using a vacuum film forming apparatus, argon gas was introduced to obtain 0.4 Pa (3 × 10 ⁻³ Torr). Under the conditions, a FeCo film having a thickness of 200 nm was formed on a silicon substrate to obtain a disk-shaped magnetic transfer master disk 46 having an outer diameter of 95 mm (3.5 type). The master disk 46 was provided with 150 radial line patterns (at intervals of 2.4 °) at regular intervals within a radius of 35 mm to 70 mm. This master disk 46 had a coercive force Hc of 8 kA / m (100 Oe) and a magnetic flux density Ms of 28.9 T (23000 Gauss).
[Production of slave disk]
The slave disk 40 was a thin glass hard disk. After reducing the pressure to 1.33 × 10 ⁻⁵ Pa (10 ⁻⁷ Torr) at room temperature using a vacuum film forming apparatus, argon gas was introduced to obtain 0.4 Pa (3 × 10 ⁻³ Torr). Under the conditions, the glass plate was heated to 200 ° C., and a hard disk having an outer diameter of 95 mm (3.5 type) having a magnetic layer with a CoCrPt film thickness of 25 nm and a magnetic flux density Ms of 5.7 T (4500 Gauss) was produced. .
[Initial magnetization (DC demagnetization) method]
A magnetic field was applied to the slave disk 40 using a device in which an electromagnet 50 as shown in FIG. The initial DC magnetization of the slave disk 40 was performed so that the peak magnetic field intensity was 397 kA / m (5000 Oe) on the surface of the slave disk 40.
[Example 1 and Comparative Example 1]
(Magnetic transfer method)
A magnetic disk is applied in a direction opposite to the magnetization of the slave disk 40 by using an apparatus in which the slave disk 40 and the master disk 46 that have been initially DC magnetized are brought into close contact with each other and permanent magnets 60 as shown in FIG. Applied. At this time, the permanent magnets 60, 60 in FIG. 6 are moved closer to the master disk 46 and the slave disk 40 while rotating, and the magnetic field peak intensity when the permanent magnet 60 is closest to the slave disk 40 is 238 kA / m (3000 Oe). ) Was applied. Other conditions are shown in the table of FIG.

  As shown in the table of FIG. 7, the rotational speed of the slave disk 40 (master disk 46) was 80 rpm (in part, 160 rpm), and the rotational speed unevenness was changed to 5 to 40%. That is, in Example 1, the rotational speed unevenness was changed to 5% (Example 1-1) to 30% (Example 1-3), and in Comparative Example 1, the rotational speed unevenness was 15% (Comparative Example 1). -3) to 40% (Comparative Example 1-1).

In addition, the rotation of the slave disk 40 when the peak magnetic field strength was applied was changed in part with respect to 360 ° (3600 ° in Example 1-4, 365 ° in Comparative Example 1-3). .
(Electromagnetic characteristic evaluation)
The transfer signal of the slave disk 40 was evaluated using an electromagnetic conversion characteristic measuring device (manufactured by Kyodo Electronics, model number: SS · 60). As the head, an inductive head having a head gap of 0.32 μm and a track width of 3.0 μm was used. The position of the radius 50 mm of the slave disk 40 was determined for one round, and the maximum output voltage V _1MAX and the minimum output voltage V _1MIN at that time were determined. The value of V _1MAX / V _1MIN under each condition is shown in the table of FIG.

According to the table of FIG. 7, the value of V _1MAX / V _1MIN in each example is good and is 1.32 at the maximum. On the other hand, the value of V _1MAX / V _{1MIN in} the comparative example is large and inferior to the results of the examples.
[Example 2 and Comparative Example 2]
(Magnetic transfer method of Example 2)
Using the apparatus of FIG. 6 in which the slave disk 40 and the master disk 46 that have been initially DC magnetized are brought into close contact with each other and the permanent magnets 60 having a magnetic field intensity distribution as shown in the graph of FIG. A magnetic field was applied in the direction opposite to the magnetization of. That is, the permanent magnet 60 linearly increases the magnetic field strength from the radial position 35 mm of the slave disk 40 to the radial position 70 mm. The magnetic field application conditions at this time were the same as those in Example 1-2.
(Magnetic transfer method of Comparative Example 2)
The slave disk 40 using the apparatus shown in FIG. 6 in which the slave disk 40 and the master disk 46 that have been initially DC magnetized are brought into close contact with each other, and permanent magnets 70 having a magnetic field intensity distribution as shown in the graph of FIG. A magnetic field was applied in the direction opposite to the magnetization of. That is, the permanent magnet 70 makes the magnetic field strength substantially uniform from the radial position 35 mm of the slave disk 40 to the radial position 70 mm. The magnetic field application conditions at this time were the same as those in Example 1-2.
(Electromagnetic property evaluation method)
The transfer signal of the slave disk 40 was evaluated using an electromagnetic conversion characteristic measuring device (manufactured by Kyodo Electronics, model number: SS · 60). As the head, an inductive head having a head gap of 0.32 μm and a track width fluctuation of 3.0 μm was used. The radius 35 mm to 70 mm of the slave disk 40 was measured at 1 mm pitch, and the average value of each circumference was calculated. These maximum values were set to _V2MAX , the minimum value was set to _V2MIN, and _V2MAX / _V2MIN was _{calculated |} required.

This value V _2MAX / V _2MIN was 1.13 in Example 2, and 1.50 in Comparative Example 2.
[Example 3 (3-1, 3-2) and Comparative Example 3]
(Magnetic transfer method of Example 3-1)
The slave disk 40 and the master disk 46 that are initially DC magnetized are brought into close contact with each other, and the electromagnet 80 as shown in FIG. 10 is used to move the electromagnet 80 from the inside to the outside of the slave disk 40, Applied a magnetic field in the opposite direction. The magnetic field application conditions at that time are such that the rotation speed of the slave disk 40 (master disk 46) is a constant rotation of 60 rpm, and the applied magnetic field strength is 279 kA / m (3500 Oe) when the electromagnet 80 is at a radius of 35 mm. The electromagnet 80 was gradually increased toward the radius of 70 mm, and was 397 kA / m (5000 Oe) when the electromagnet 80 was at a radius of 70 mm.
(Magnetic transfer method of Example 3-2)
The slave disk 40 and the master disk 46 that are initially DC magnetized are brought into close contact with each other, and the electromagnet 80 as shown in FIG. 10 is used to move the electromagnet 80 from the inside to the outside of the slave disk 40, Applied a magnetic field in the opposite direction. At that time, the applied magnetic field strength was a constant strength of 297 kA / m (3500 Oe), and the electromagnet was moved from a radius of 35 mm toward a radius of 70 mm. At this time, the rotational speed of the slave disk 40 is set to 70 rpm when the electromagnet 80 is located at a radius of 35 mm. When the disk reaches a position with a radius of 70 mm, the rotational speed of the slave disk 40 is set to 35 rpm.
(Magnetic transfer method of Comparative Example 3)
The slave disk 40 and the master disk 46 that are initially DC magnetized are brought into close contact with each other, and the electromagnet 80 as shown in FIG. 10 is used to move the electromagnet 80 from the inside to the outside of the slave disk 40, Applied a magnetic field in the opposite direction.

As magnetic field application conditions at that time, the rotation speed of the slave disk 40 (master disk 46) was a constant rotation of 60 rpm, and the applied magnetic field intensity was a constant intensity of 238 kA / m (3000 Oe).
(Electromagnetic property evaluation method)
The transfer signal of the slave disk 40 was evaluated using an electromagnetic conversion characteristic measuring device (manufactured by Kyodo Electronics, model number: SS · 60). As the head, an inductive head having a head gap of 0.32 μm and a track width fluctuation of 3.0 μm was used. The slave disk 40 was measured with a radius of 35 mm to 70 mm at a pitch of 1 mm, and the average value of each circumference was calculated. These maximum values were set to _V2MAX , the minimum value was set to _V2MIN, and _V2MAX / _V2MIN was _{calculated |} required.

This value V _2MAX / V _2MIN was 1.05 in Example 3-1, 1.06 in Example 3-2, and 1.70 in Comparative Example 3.

1 is a perspective view of a main part of a magnetic transfer apparatus for carrying out a magnetic transfer method according to the present invention. Plan view showing how to apply magnetic field for transfer Diagram showing basic steps of magnetic transfer method The figure which shows the other structure of a magnetic field production | generation means Perspective view showing an example of DC demagnetization method Perspective view showing an example of a magnetic transfer method Table showing results of Example 1 and Comparative Example 1 Graph showing magnetic field strength distribution to be applied Graph showing magnetic field strength distribution to be applied A perspective view showing still another example of the magnetic transfer method

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Magnetic transfer apparatus 22, 24, 26 ... Magnetic field production | generation means, 30 ... Magnetic field production | generation means, 31 ... Gap, 32 ... Core, 33 ... Coil, 34 ... Electromagnet apparatus, 40 ... Slave disk (disc for transfer), 46 ... Master disk

Claims (11)

An adhesion step for closely adhering a magnetic recording medium to be transferred, which is initially DC magnetized, and a master medium having a magnetic pattern;
While providing a magnetic field generating means and moving the transferred magnetic recording medium and the master medium in close contact with the magnetic field generating means, the circumferential direction of the transferred magnetic recording medium and the master medium The master is set such that the maximum value of the magnetic field strength applied to each part of the medium is within the range of maximum magnetic field strength × 0.7 to maximum magnetic field strength over substantially the entire surface of the magnetic recording medium for transfer. A magnetic transfer step of transferring a magnetic pattern of the medium to the magnetic recording medium for transfer;
A magnetic transfer method comprising: A magnetic recording medium to be transferred that depends on the application time of the magnetic field to which the coercive force is applied, and an adhesion step in which the magnetic recording medium to be transferred that is initially DC magnetized and the master medium having a magnetic pattern are closely attached;
While providing a magnetic field generating means and moving the transferred magnetic recording medium and the master medium in close contact with the magnetic field generating means, the circumferential direction of the transferred magnetic recording medium and the master medium The magnetic pattern of the master medium is transferred so that the coercive force is in the range of maximum coercive force × 0.7 to maximum coercive force over substantially the entire surface of the magnetic recording medium to be transferred. A magnetic transfer process for transferring to a magnetic recording medium,
A magnetic transfer method comprising:   3. The speed fluctuation of the relative movement speed for relatively moving the magnetic recording medium to be transferred and the master medium in close contact with the magnetic field generating means is controlled within ± 15%. The magnetic transfer method described in 1.   The magnetic field generating means has substantially the same length as the radius of the magnetic recording medium for transfer, and the applied magnetic field strength of the magnetic field generating means is increased from the inner circumference side to the outer circumference side of the magnetic recording medium for transfer. The magnetic transfer method according to claim 1, wherein the magnetic transfer method is a magnetic transfer method.   The magnetic field generating means has a length shorter than the radius of the magnetic recording medium, and the applied magnetic field strength of the magnetic field generating means is set to the magnetic field for transfer while moving the magnetic field generating means in the radial direction of the magnetic recording medium for transfer. The magnetic transfer method according to claim 1, wherein the magnetic transfer method increases from the inner circumference side to the outer circumference side of the recording medium.   The magnetic field generating means has a length shorter than the radius of the magnetic recording medium, the magnetic field generating means is moved in the radial direction of the magnetic recording medium for transfer, and the magnetic field generating means, the magnetic recording medium for transfer, and the 3. The magnetic transfer method according to claim 1, wherein a relative rotational speed with respect to the master medium is decreased from the inner circumference side to the outer circumference side of the magnetic recording medium for transfer.   The number of times of applying a magnetic field in the circumferential direction of the magnetic recording medium for transfer and the master medium is set to be the same for each portion in the surface of the magnetic recording medium for transfer. 7. The magnetic transfer method according to any one of 6 above.   The number of times of applying a magnetic field in the circumferential direction of the magnetic recording medium for transfer and the master medium is set to be once for each portion in the plane of the magnetic recording medium for transfer. 8. The magnetic transfer method according to any one of 7 above.   The portion of the number of times of applying the magnetic field in the circumferential direction of the magnetic recording medium for transfer and the master medium that does not become the same number in the plane of the magnetic recording medium for transfer is less than 1 degree in the circumferential angle. The magnetic transfer method according to claim 1, wherein the magnetic transfer method is performed.   The magnetic field generating means in a magnetic transfer preparation stage for increasing the magnetic field strength to a strength required for the magnetic transfer, or in a magnetic transfer end stage for lowering the magnetic field strength from a strength required for the magnetic transfer; The relative movement speed of the magnetic recording medium to be transferred and the master medium in close contact with each other is determined with respect to the magnetic recording medium to be transferred and the master medium in close contact with the magnetic field generating means in the magnetic transfer. The magnetic transfer method according to claim 1, wherein the magnetic transfer method is higher than a relative moving speed. A close contact means for bringing a magnetic recording medium to be transferred and a master medium having a magnetic pattern into close contact with each other;
While providing a magnetic field generating means and moving the transferred magnetic recording medium and the master medium in close contact with the magnetic field generating means, the circumferential direction of the transferred magnetic recording medium and the master medium The master is set such that the maximum value of the magnetic field strength applied to each part of the medium is within the range of maximum magnetic field strength × 0.7 to maximum magnetic field strength over substantially the entire surface of the magnetic recording medium for transfer. Magnetic transfer means for transferring the magnetic pattern of the medium to the magnetic recording medium for transfer;
A magnetic transfer apparatus comprising:

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