JP2007026567A - Magnetic recording medium, magnetic transfer method, and magnetic reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium in which influence of a sub-pulse when magnetic transfer is performed can be eliminated and which copes with high density recording, a magnetic transfer method, and a magnetic reproducing method. <P>SOLUTION: The magnetic recording medium of a disk type is constituted so that a plurality of magnetic layer patterns and non-magnetic layer patterns provided between these magnetic layer patterns are formed alternately on the surface, thereby recording magnetic information. When the minimum value of length in the circumferential direction of the magnetic layer patten and/or the non-magnetic layer pattern is larger than (b) and it is length in the circumference direction which causes the sub-pulse P<SB>s</SB>becoming a reading error when reading is performed by a magnetic head, position information of the prescribed magnetic layer pattern and/or the non-magnetic layer pattern are recorded as magnetic information. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium, a magnetic transfer method, and a magnetic reproduction method, and more particularly, a magnetic recording 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. The present invention relates to a medium, a magnetic transfer method, and a magnetic reproduction method.

  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.

  This magnetic transfer has the advantage that recording can be performed statically without changing the relative positions of the master disk and slave disk, and the time required for recording is extremely short.

  In particular, with advances in ultra-fine processing technology represented by recent electron beam lithography technology, signal patterning with a minimum bit length of 100 nm or less is also possible, and batch writing of signals equivalent to the current hard disk surface density is magnetically transferred. It has become possible to do this.

Conventionally, various proposals have been made as this type of magnetic transfer technology (for example, Patent Documents 1 and 2). The proposal of Patent Document 1 is to perform batch transfer from a master disk in which a concavo-convex shape made of a magnetic material corresponding to an information signal is formed on the surface of a substrate. The proposal of Patent Document 2 improves the adhesion between the master disk and the slave disk during magnetic transfer. These proposals suggest that high-density magnetic transfer can be performed.
JP 10-40544 A Japanese Patent Laid-Open No. 10-269566

  However, as one of the technical problems in the magnetic transfer method, in the signal transfer from the master medium (master disk) to the slave medium (slave disk), an unclear magnetic recording portion (reversal magnetization) on the slave medium. There is a problem that occurs. This will be described with reference to FIG. This problem is a problem inherent to magnetic transfer that has not occurred in writing by a conventional magnetic head.

FIG. 9 is a diagram showing a pulse waveform of the transfer signal. When normal magnetic transfer is performed, as shown in (a), positive pulse waveforms P _P , P _P ... And negative pulse waveforms P _N , P _N. However, normal magnetic transfer is not performed, and as shown in (b), subpulses P _S , P _S ..., Which are false pulses, are placed between the positive pulse waveform P _P and the negative pulse waveform P _N. May occur.

The magnitude of the amplitude height of the sub-pulse P _S is important with respect to the amplitude height of the original pulse (positive pulse P _P and negative pulse P _N ). That is, when the amplitude height of the sub-pulse P _S is a level that cannot be ignored with respect to the amplitude height of the original pulse, it becomes difficult to distinguish from the original pulse, and the sub-pulse is recognized as a reproduction signal and an error occurs. It will be.

  Although there are many unclear points in the sub-pulse generation mechanism, it has been found that it can be suppressed by using a magnetic substrate as the master medium substrate and adjusting transfer conditions such as the adhesion pressure between the master medium and the slave medium. It was. However, subpulses cannot be completely suppressed. For this reason, even if a unique sub-pulse is generated by magnetic transfer, it is necessary to be able to perform signal processing similar to the recording / reproducing system of the magnetic recording medium.

  The present invention has been made in view of such circumstances, and provides a magnetic recording medium, a magnetic transfer method, and a magnetic reproduction method that can remove the influence of sub-pulses when performing magnetic transfer and are compatible with high-density recording. For the purpose.

  In order to achieve the above object, according to the present invention, a plurality of magnetic layer patterns and nonmagnetic layer patterns provided between the magnetic layer patterns are alternately formed on the surface, thereby recording magnetic information. A disc-shaped magnetic recording medium, wherein a minimum value of a circumferential length of the magnetic layer pattern and / or the nonmagnetic layer pattern is b, and the predetermined magnetic layer pattern and / or the non-magnetic layer When the circumferential length of the magnetic layer pattern is greater than b and the circumferential length is such that a sub-pulse that causes a reading error when read by a magnetic head is used, the predetermined magnetic layer pattern and / or non- There is provided a magnetic recording medium in which position information of a magnetic layer pattern is recorded as magnetic information.

  As a result of various studies for solving the above problems, the present inventors have found that sub-pulses are generated when the recording signal pattern interval is long (bit interval is long). That is, it has been found that when the signal pattern interval is long with relatively little waveform interference, a sub-pulse is generated together with the reproduced waveform. Details of this will be described later with reference to the drawings.

  For this reason, information indicating the presence / absence of magnetic transfer and a transfer signal with a sufficiently long pattern interval are recorded in advance, detection of the presence / absence of magnetic transfer when reading the signal, and sub-pulse information (sub-pulse position, sub-pulse peak). When the magnetic transfer is performed, signal processing can be performed via a circuit that cancels the sub-pulse signal. As a result, a magnetic transfer system medium (slave disk) can be used by being incorporated in a magnetic recording system recording / reproducing apparatus (hard disk drive).

  Therefore, according to the present invention, it is possible to eliminate the influence of sub-pulses when performing magnetic transfer and to obtain a magnetic recording medium compatible with high-density recording.

  The magnetic recording medium may be a master medium (master disk) or a slave medium (slave disk).

  In the magnetic recording medium of the present invention, servo wedges in which positioning information is recorded and data areas in which read information is recorded are alternately formed in the circumferential direction on the surface of the disk-shaped body, The position information of the magnetic layer pattern and / or the nonmagnetic layer pattern is preferably recorded in a part of the data area.

  As described above, if the servo wedge and the data area are alternately formed in the circumferential direction, and the sub-pulse information is recorded in a part of the data area, it is convenient for use.

  The normal magnetic recording medium (slave disk) has positioning information recorded on the servo wedge, and the other part (gap) is provided to record the write information. Depending on the trend, it is expected that the manner in which information is recorded and supplied (sales, etc.) to the data area will also increase, which is effective in the case of such a read-only disc.

  Further, in the magnetic recording medium of the present invention, servo wedges on which positioning information is recorded and gaps provided for recording write information are alternately formed in the circumferential direction on the surface of the disk-shaped body. Preferably, the positional information of the predetermined magnetic layer pattern and / or nonmagnetic layer pattern is recorded in a part of the gap.

  Thus, it is convenient in use if servo wedges and gaps are alternately formed in the circumferential direction, and sub-pulse information is recorded in a part of the gap.

  In addition, the present invention uses the magnetic recording medium as a master medium for magnetic transfer, and provides an adhesion process for bringing the master medium and a medium to be transferred into close contact with each other, and a magnetic field generation unit, And a magnetic transfer step of applying a magnetic field in the circumferential direction of the master medium to transfer the magnetic pattern of the master medium to the medium to be transferred.

  If such a magnetic recording medium is used as a master medium for magnetic transfer and magnetic transfer to a slave disk is performed, subpulse information can be easily read, so that accurate magnetic transfer can be performed.

  The magnetic transfer method of the present invention may include an initial magnetization step of applying a magnetic field in the circumferential direction of the medium to be transferred and initial DC magnetization of the medium to be transferred in the circumferential direction before the adhesion step. preferable. If such an initial magnetization step is provided, more accurate magnetic transfer can be performed.

  Further, in the magnetic transfer method of the present invention, during the magnetic transfer process, the position information of the predetermined magnetic layer pattern and / or nonmagnetic layer pattern is used during the magnetic transfer process or after the magnetic transfer process. It is preferable to remove the generated sub-pulse. Thus, if the sub-pulse generated during the magnetic transfer process can be removed, accurate magnetic transfer can be performed.

  In the present invention, the magnetic recording medium is used as a master medium for magnetic transfer, the master medium is brought into close contact with the medium to be transferred, and a magnetic field is applied in a circumferential direction between the medium to be transferred and the master medium. In addition, there is provided a magnetic reproducing method for reading out the magnetic recording information magnetically transferred from the medium to be transferred by magnetic transfer of the magnetic pattern of the master medium by a magnetic head, wherein a predetermined magnetic layer pattern and / or nonmagnetic layer There is provided a magnetic reproducing method characterized in that sub-pulses generated during the magnetic transfer are removed from pattern position information.

In this way, accurate magnetic reproduction can be performed if sub-pulses generated during magnetic transfer are removed from position information of sub-pulses during reproduction.
The

  As described above, according to the present invention, it is possible to eliminate the influence of sub-pulses when performing magnetic transfer, and it is possible to cope with high-density recording.

  Hereinafter, preferred embodiments of a magnetic recording medium, a magnetic transfer method, and a magnetic reproduction method according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a magnetic layer pattern of a magnetic transfer master disk 46 which is a magnetic recording medium. On the surface of the master disk 46, magnetism called a gap 10B, 10B,... Formed between the servo wedges 10A, 10A,. The portions with almost no layer (white background portions) are alternately formed. In the gap 10B, a magnetic layer pattern corresponding to the position information of the subpulse is formed at the head portion.

  FIG. 2 shows a waveform of a signal reproduced when the magnetic head is rotated or the magnetic disk magnetically transferred by the master disk 46 (slave disk) is rotated and the magnetic head passes through the servo wedges 10A, 10A. Is shown. In FIG. 2, the range of the period T10A is a signal for one pitch of the servo wedge 10A, and the period T10B is a signal for one pitch of the gap 10B (no signal).

  The signal for one pitch of the servo wedge 10A is the first preamble 50, the servo timing mark 52, the sector address 54, the cylinder address 56, and the burst signal 58 (58A, 58B, 58C, fixed cycle) from the top (left). And 58D), and the last preamble 60.

  FIG. 3 is a partially enlarged perspective view showing a fine protrusion pattern on the surface of the master disk 46. The master disk 46 is formed in a disk shape, and a transfer information carrying surface is formed on one surface of the substrate 47, on which a fine projection pattern is formed by the magnetic layer 48, and the opposite surface of the substrate 47 is in close contact with the unillustrated surface. Held in the means. The fine protrusion pattern is formed by a photofabrication method to be described later. One side (transfer information carrying surface) of the master disk 46 is in close contact with the slave disk 40.

  The fine protrusion pattern is rectangular in plan view, and in the state where the magnetic layer 48 having a thickness t is formed, the length b in the track direction (thick arrow direction in the figure) and the length l in the radial direction. And more. The optimum values of the lengths b and l vary depending on the recording density, the recording signal waveform, and the like. For example, the length b can be 80 nm and the length l can be 200 nm.

  In the case of a servo signal, this fine projection pattern is formed long in the radial direction. In this case, for example, the length l in the radial direction is preferably 0.05 to 20 μm, and the length in the track direction (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 depth of the fine projection pattern on the surface of the substrate 47 (projection height) is preferably in the range of 80 to 800 nm, and more preferably in the range of 100 to 600 nm.

  As described above, the fine protrusion-shaped magnetic layer 48 on the surface of the substrate 47 corresponds to the magnetic layer pattern, and the recesses between the fine protrusion patterns correspond to the non-magnetic layer pattern.

  In the master disk 46, when the substrate 47 is a ferromagnetic material mainly composed of Ni or the like, magnetic transfer can be performed only by the substrate 47, and the magnetic layer 48 may not be covered, but the transfer characteristics are good. By providing the magnetic layer 48, 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 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 48, Co, Co alloy (CoNi, CoNiZr, CoNbTaZr, etc.), Fe, Fe alloy (FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, FeTaN), Ni, Ni alloy (NiFe) should be used. Can do. In particular, FeCo and FeCoNi can be preferably used. The thickness t of the magnetic layer 48 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 is a flash in the molded product, it is 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.

  Next, the slave disk 40 (see FIGS. 4 to 7) will be described. 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. This underlayer needs to match the crystal structure and lattice constant to the magnetic layer 48. For that purpose, it is preferable to use Cr, CrTi, CoCr, CrTa, CrMo, NiAl, Ru or the like.

  Next, an outline of magnetic transfer will be described. FIG. 4 is a perspective view of a main part of the magnetic transfer apparatus 10 for performing magnetic transfer using the magnetic transfer master disk 46.

  At the time of magnetic transfer, the slave surface (magnetic recording surface) of the slave disk 40 after initial DC magnetization described later shown in FIG. 5A is brought into contact with the information carrying surface (magnetic layer 48) of the master disk 46, Adhere 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 is applied by the magnetic field generating means 30 to transfer the uneven pattern of the master disk 46 to the slave disk 40.

  The magnetic transfer by the master disk 46 is performed when the master disk 46 is brought into close contact with one side of the slave disk 40 and the transfer is performed with one side of the slave disk 40, although not shown, a pair of master disks 46 are brought into close contact with both sides of the slave disk 40. There are cases where simultaneous transfer is performed.

  The magnetic field generating means 30 for applying the transfer magnetic field includes electromagnet devices 34, 34 each having a coil 33 wound around a core 32 having a gap 31 extending in the radial direction between the slave disk 40 and the master disk 46 held in close contact with each other. A transfer magnetic field having magnetic field lines parallel to the track direction is applied in the same direction in the vertical direction.

  When a magnetic field is applied, a magnetic field for transfer is applied by the magnetic field generating means 30 while rotating the slave disk 40 and the master disk 46 integrally, and the uneven pattern of the master disk 46 is magnetically transferred to the slave surface of the slave disk 40. . In addition to this configuration, the magnetic field generation means may be rotated.

  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 in the optimum transfer magnetic field strength range at any position in the track direction. A magnetic field having a certain magnetic field intensity distribution is generated in a part of the track direction.

  FIG. 5 is an explanatory diagram for explaining the basic steps of the magnetic transfer method using in-plane recording. FIG. 6 is a perspective view of the same. First, as shown in FIG. 5A, initial magnetization (DC demagnetization) is applied to the slave disk 40 by applying an initial magnetic field Hi in one direction in the track direction in advance.

  Next, as shown in FIGS. 5B and 6, the recording surface (magnetic recording portion) of the slave disk 40 and the information carrying surface of the master disk 46 on which the concave / convex pattern P is formed are brought into close contact with each other. Magnetic transfer is performed by applying a transfer magnetic field Hd in the direction opposite to the initial magnetic field Hi in the track direction of the disk 40. As shown in FIG. 5C and FIG. 6, the transfer magnetic field Hd is sucked into the magnetic layer 48 of the convex part of the concavo-convex pattern and the magnetization of this part is not reversed, and the magnetic field of the other part is reversed. The concave / convex pattern of the master disk 46 is magnetically transferred and recorded on the magnetic recording surface of the slave disk 40.

Next, a method for removing the influence of sub-pulses, which is a characteristic part of the present invention, will be described. 7A and 7B are explanatory diagrams for explaining the influence of the sub-pulse. FIG. 7A shows a case where normal magnetic transfer is performed, and FIG. 7B shows a positive pulse waveform without performing normal magnetic transfer. A case where a sub-pulse P _S which is a false pulse is generated between P _P and a negative pulse waveform P _N is shown.

In FIG. 7A, even if there is a nonmagnetic layer pattern having a circumferential length nb that is n times the minimum value b of the circumferential length of the magnetic layer pattern, no sub-pulse P _S is generated. As shown in FIGS. 5 and 6 described above, normal magnetic transfer is performed.

On the other hand, in FIG. 7 (b), the nonmagnetic layer pattern of circumferential length nb is n times the minimum value b of the circumferential length of the magnetic layer pattern, the sub-pulse P _S is generated, thereby Magnetization reversal occurs in the corresponding part, and normal magnetic transfer is not performed.

The value of n times b for generating the sub-pulse P _S depends on the configuration of the master disk 46 and the slave disk 40, magnetic transfer conditions (magnetic field strength, etc.), the length of b, etc. If n is 10 or more, it occurs almost certainly, and may occur even when n is 8.

Therefore, if the position information of the sub pulse P _S is recorded as magnetic information under the condition that the sub pulse P _S is generated by the magnetic transfer, the position of the sub pulse P _S is easy when various magnetic information is read by the magnetic head. to understand, or clear an area of the sub-pulse P _S, by or to not play the area of the sub-pulse P _S, can eliminate the influence of sub-pulses.

At this time, the zone where the position information of the sub-pulse P _S is recorded as magnetic information is preferably the head portion of the gap 10B in the case of the master disk 46, and is a slave disk 40 (read-only disk) in which read information is recorded in advance. If there is, the head portion of the data area is preferable, and if it is a normal slave disk 40, the head portion of the gap is preferable. However, it can be recorded in other zones, for example, at the end of a gap or data area, or in a part of a servo wedge.

  According to the above configuration, it is possible to eliminate the influence of sub-pulses when performing magnetic transfer, and to cope with high-density recording.

  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.

  As described above, the embodiments of the magnetic recording medium, the magnetic transfer method, and the magnetic reproduction method according to the present invention have been described.

  For example, in the above embodiment, as shown in FIG. 3, the magnetic layer 48 (corresponding to the magnetic layer pattern) of the fine projection pattern on the surface of the substrate 47 of the master disk 46 and the fine projection pattern The concave portion (corresponding to the nonmagnetic layer pattern) between them forms a transfer information carrying surface, but other modes can also be adopted.

  FIG. 8 is a partial enlarged cross-sectional view of the master disk 46 showing this example. Among these, (a) is an aspect in which a magnetic layer 48 having a fine protrusion pattern is formed on the surface of a nonmagnetic flat substrate 47, and a space between the magnetic layers 48 is a nonmagnetic layer pattern. In b), a magnetic layer 48 having a fine pattern is embedded in the surface of the nonmagnetic substrate 47, and a nonmagnetic layer pattern is formed between the magnetic layers 48, so that the surface of the substrate 47 becomes flat. It is the aspect which is. The present invention can be suitably applied even to the master disk 46 having such an aspect.

The figure which showed the magnetic layer pattern of the master disk for magnetic transfer The figure which showed the waveform of the signal reproduced when a magnetic head passes a servo wedge Partial enlarged perspective view showing fine protrusion pattern on the surface of the master disk Perspective view of main part of magnetic transfer device Explanatory drawing explaining the basic process of the magnetic transfer method Perspective view showing basic steps of magnetic transfer method Explanatory drawing explaining the influence of subpulse Partial enlarged sectional view of a master disk showing another example Diagram showing pulse waveform of transfer signal

Explanation of symbols

10 ... magnetic transfer apparatus, 30 ... magnetic field generating means, 31 ... gap, 32 ... core, 33 ... coil, 34 ... electromagnet device 40 ... slave disk (disk for the transfer), 46 ... master disk, P _S ... subpulse

Claims (7)

A disk-shaped magnetic recording medium in which a plurality of magnetic layer patterns and nonmagnetic layer patterns provided between the magnetic layer patterns are alternately formed on the surface, thereby recording magnetic information. ,
The minimum value of the circumferential length of the magnetic layer pattern and / or the nonmagnetic layer pattern is b, and the circumferential length of the predetermined magnetic layer pattern and / or the nonmagnetic layer pattern is larger than b. In addition, when the length is in the circumferential direction that generates a sub-pulse that causes a reading error when read by the magnetic head, the positional information of the predetermined magnetic layer pattern and / or nonmagnetic layer pattern is recorded as magnetic information. A magnetic recording medium comprising:   Servo wedges in which positioning information is recorded and data areas in which read information is recorded are alternately formed in the circumferential direction on the surface of the disk-like body, and a predetermined magnetic layer pattern and / or non-magnetic layer in the previous period. 2. The magnetic recording medium according to claim 1, wherein position information of a layer pattern is recorded in a part of the data area.   Servo wedges in which positioning information is recorded and gaps provided for recording write information are alternately formed in the circumferential direction on the surface of the disk-shaped body, and a predetermined magnetic layer pattern and / or 2. The magnetic recording medium according to claim 1, wherein position information of the nonmagnetic layer pattern is recorded in a part of the gap. Using the magnetic recording medium according to any one of claims 1 to 3 as a master medium for magnetic transfer, an adhesion step for bringing the master medium and a medium to be transferred into close contact with each other;
A magnetic transfer step of providing a magnetic field generating means, applying a magnetic field in a circumferential direction of the medium to be transferred and the master medium, and transferring a magnetic pattern of the master medium to the medium to be transferred;
A magnetic transfer method comprising:   5. The method according to claim 4, further comprising an initial magnetization step of applying a magnetic field in a circumferential direction of the medium to be transferred and performing initial direct current magnetization in the circumferential direction before the adhesion step. Magnetic transfer method.   In the magnetic transfer process or after the magnetic transfer process, sub-pulses generated during the magnetic transfer process are removed from position information of a predetermined magnetic layer pattern and / or nonmagnetic layer pattern in the previous period. The magnetic transfer method according to claim 4 or 5. A magnetic recording medium according to any one of claims 1 to 3 is used as a master medium for magnetic transfer, the master medium is brought into close contact with a medium to be transferred, and a circle between the medium to be transferred and the master medium. A magnetic reproducing method of applying a magnetic field in the circumferential direction and reading out the magnetically transferred magnetic recording information from the medium to be transferred from the magnetic recording medium on which the magnetic pattern of the master medium is magnetically transferred,
A magnetic reproducing method comprising removing sub-pulses generated during the magnetic transfer from position information of a predetermined magnetic layer pattern and / or non-magnetic layer pattern in the previous period.

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