JP2007207385A - Patterned medium having clock information track and magnetic disk apparatus mounting patterned medium and clock reproduction head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately perform recording timing synchronization to a bit pattern arrangement in a patterned medium. <P>SOLUTION: A clock information track 13 for generating a clock signal is disposed on the patterned medium 34 and the signal formed by reproducing the clock information track 13 by using a clock reproduction head is used as a standard of a recording current inversion timing. The clock signal reproduced from a clock signal track reflects rotation run-out of a spindle motor in a disk apparatus and the rotation run-out is used as a trigger to highly accurately synchronize arrangement of an effective region of the patterned medium with the timing of recording magnetic field polarity inversion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bit area demarcating type recording medium, that is, a pattern medium, and a magnetic recording / reproducing apparatus using the same.

  Digitization is progressing rapidly in various fields, prompted by the development of information processing technology. In addition to personal computers and servers that have traditionally represented hardware, the need to store large amounts of digital data in home appliances, audio, and medical devices has increased. In order to store these enormous amounts of data, magnetic disk devices (HDDs), which are the core of nonvolatile file systems, are required to have a larger capacity than ever before. Increasing the capacity of the magnetic disk device means increasing the surface recording density, that is, the bit density recorded on the medium.

  In HDDs currently in practical use, a recording medium composed of a ferromagnetic polycrystalline thin film is used for both in-plane recording and perpendicular recording. FIG. 1 is a schematic diagram of a recording state in a conventional magnetic recording medium. A conventional polycrystalline thin film is generally composed of magnetic particles 101 having high uniaxial magnetic anisotropy and a nonmagnetic material 102 surrounding the magnetic particles 101. The basic operation for recording information is to apply a local magnetic field to an arbitrary position on the recording medium, and to reverse the magnetization polarity at an appropriate timing to change the magnetization at approximately 180 ° (magnetization transition 103). This magnetization transition 103 is made to correspond to 1 of digital information. Moreover, detecting the spatial change of the leakage magnetic field distribution in the vicinity of the magnetization transition 103 with an appropriate magnetic field sensor corresponds to data reproduction. Actually, input / output of information in the HDD is performed before and after the recording / reproducing operation, including processing such as encoding / decoding. The recording density is the number of magnetization transitions 103 that can be written in a unit area, and the most important factor for increasing this is how sharply and smoothly each magnetization transition 103 can be formed. This magnetization transition 103 usually has a zigzag microstructure along the grain boundary, as shown in FIG. It can be said that the average width (transition width) of this zigzag represents the steepness of the magnetization transition. If this width is too wide, not only the recording interval does not increase because the bit interval cannot be reduced, but also a large noise is added to the reproduction signal, so that stable reading at a low bit error rate (BER) is impossible. There's a problem. Therefore, in the current magnetic recording system, the transition width is one of the biggest factors limiting the recording density.

  Various means are conceivable for reducing the width of the magnetization transition 103. In particular, as an approach from a medium material, it is first important to reduce the zigzag by making the magnetic particles 101 smaller. However, if the magnetic particle 101 is excessively miniaturized, the magnitude of the thermal energy (energy that destabilizes the magnetization) relative to the magnetic anisotropy energy (energy that tries to direct the magnetization in one direction) cannot be ignored. It becomes difficult to store the recorded bits for a long period (usually about 10 years). In order to prevent this, if the magnetic anisotropy energy of the magnetic particle 101 is excessively increased, it is difficult to reverse the magnetization by the recording magnetic field from the magnetic head, and information cannot be written.

In order to solve this problem, the so-called ultimate magnetic recording medium is a patterned medium. As shown in FIG. 2, an area where data can be recorded (hereinafter referred to as an effective area 21) and an area where data cannot be recorded (hereinafter referred to as an invalid area 22) are preliminarily built in the apparatus before being incorporated into the apparatus. A defined recording medium. As a manufacturing method of the pattern medium, some lithography technique is used. However, in addition to the method of making the concave portion the ineffective area 22 by making the concave and convex as shown in FIG. 2, the magnetism of a part of the medium recording layer is changed. A manufacturing method is also possible in which the ineffective region 22 is substantially obtained by changing the composition and / or the film structure to reduce the coercive force (for example). When this pattern medium is used, one magnetically isolated effective area 21 itself or an invalid area 22 between two adjacent effective areas 21 corresponds to 1 bit, and the magnetization in this effective area is a magnetic field. The material, structure, and dimensions are designed to switch almost simultaneously when applied. Therefore, the magnetization transition in the pattern medium is automatically generated between the effective regions 21, and the magnetization transition can be made as steep as possible within the accuracy of the pattern formation process. The concept of such a medium has been proposed since the 1970s, and the superiority to the polycrystalline thin film medium has already been clarified.
JP 2004-164692 A

  There is a big problem in actually applying a pattern medium in which a data recording area (effective area) and an unrecordable area (invalid area) are preliminarily defined before assembling the apparatus to the magnetic disk apparatus. The practical application has been considered difficult. The problem is that the timing of writing to the pattern arrangement of the effective area is synchronized with the arrangement of the effective area on the medium. As mentioned above, the magnetization transitions in the patterned medium must be generated between every effective area. For this reason, unless the timing for reversing the recording magnetic field polarity or the recording current polarity is properly selected, the magnetization of the subsequent effective area cannot be reversed well, and bit writing fails. On the other hand, a disk, which is a recording medium in a magnetic disk device, rotates at a high speed by driving a spindle motor. Since there is always some degree of unevenness (runout) in the rotation of the spindle motor, the timing of reversing the recording magnetic field polarity in synchronization with the external clock greatly varies with the period of the effective area. For this reason, a sufficiently small bit error rate could not be secured, and it was considered difficult to put the pattern medium to practical use.

  In the present invention, a track (clock information track) for generating a clock signal is provided on the pattern medium, and a signal obtained by reproducing the track with a clock reproducing head is used as a reference for recording current inversion timing. The pattern medium of the present invention includes a clock information track for providing a clock for writing data to the user data area in addition to the user data area and the servo area. The clock information track has a constant bit length over the entire circumference. In addition, the magnetic disk apparatus of the present invention has a pattern medium having the clock information track and a dedicated clock reproducing head for referring to the clock information track, and generates a clock signal reproduced by the clock reproducing head. In synchronization, data is written to the user data area.

The waveform of the clock signal reproduced from the clock signal track is subjected to phase modulation corresponding to the rotation unevenness of the spindle motor in the disk device, and by synchronizing the inversion timing of the recording current to this, the arrangement of the effective areas of the pattern medium The recording magnetic field polarity reversal timing can be automatically synchronized with high accuracy in real time. As a result, a small-sized and large-capacity magnetic disk device using a pattern medium having an ultrahigh recording density exceeding 500 Gb / in ² can be realized at low cost.

  Hereinafter, specific magnetic recording media and magnetic disk devices to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 3 is a schematic plan view of a magnetic recording medium according to the present invention. The pattern group composed of the effective area and the invalid area formed on the surface of the recording medium 34 is roughly divided into three. That is, a user data area 11 for recording / reproducing user data, a servo area 12 including positioning signals, track numbers, sector numbers, and the like, and a clock information track 33. Among them, the basic configuration of the clock information track 13 is composed of an island-shaped effective area 21 having the same shape, that is, a single bit length, and an ineffective area 22 surrounding the same, as shown on the right side in the drawing.

  FIG. 4 is a process sectional view showing an example of a method for producing a patterned medium having these pattern groups. First, as shown in FIG. 4A, a mask material 51 that is cured by light or heat, such as a resist or SOG (Spin on glass), is applied to the substrate 50. The substrate 50 at this time may be a chemically strengthened glass substrate or an aluminum substrate subjected to NiP plating. Next, as shown in FIG. 4B, the mask material 51 is patterned through a lithography process and a development process using an imprint technique using laser exposure, electron beam drawing, or an appropriate mold. At this time, it is important to simultaneously form at least the pattern of the user data area 11 for recording / reproducing user data and the pattern of the clock information track 13. As a result, the fluctuation in the recording timing in the user data area 11 due to the rotation irregularity of the recording medium and the fluctuation in the clock signal generated from the clock information track 13 can be exactly matched, and the recording operation on the pattern medium can be performed with high accuracy. Is guaranteed.

  Next, as shown in FIG. 4C, an appropriate amount of the mask pattern opening in the surface of the substrate 50 is etched using ion milling, reactive ion etching (RIE), or wet etching, and FIG. As shown in FIG. 4, the mask pattern and other residuals are removed by peeling and cleaning. Finally, as shown in FIG. 4E, a magnetic recording material layer 52 and a protective film 53 including a base material (such as an adhesion improving layer and a high crystal orientation upper layer) are formed by sputtering or the like. Since the irregularities formed on the surface of the substrate 50 are transferred to the surface of the magnetic recording material layer, the convex portion that is close to the magnetic head is substantially the effective area 21, and the concave portion that is far from the magnetic head is substantially It becomes an invalid area 22. If necessary, a protective film 53 is attached after forming a cross-sectional shape having a smooth surface as shown in FIG. 4F by performing an appropriate flattening step such as filling the recess with a nonmagnetic material 54. It is also possible. Also in this case, the above-described effective area 21 and invalid area 22 are the same.

  FIG. 5 is a schematic plan view of a magnetic disk device incorporating the patterned medium thus produced. The magnetic head 31 records and reproduces user data by being positioned at an arbitrary position on the rotating disk-shaped magnetic recording medium 34 by an actuator 33. This magnetic recording medium 34 is a patterned medium manufactured by the process shown in FIG. 4 and has a clock information track 13 at the outermost periphery. The magnetic disk apparatus also includes a clock reproducing head 15 for referring to the clock information track 13. The role of the clock reproducing head 15 will be described below with reference to FIGS.

  FIG. 6 is a conceptual diagram showing the relationship between the components of a magnetic disk apparatus using a conventional magnetic recording medium or a conventional patterned medium according to the prior art. The slider on which the magnetic head 31 is mounted is supported by a suspension arm 32 and is positioned on the disk-shaped magnetic recording medium 34 by an actuator 33 to read / write information at a desired location. The rotation of the magnetic recording medium 34 is controlled by a spindle motor 35, and a signal (servo signal) indicating the position is recorded in advance in a servo area above the magnetic recording medium 34, and the servo signal read by the head is processed by the mechanism control system 45. In addition, closed-loop control is performed by feeding back to the positioning mechanism 36.

  User data input through the external interface 44 is encoded and shaped by the controller 43 and the data encoding / decoding system 42 by a method suitable for the magnetic recording system, and converted into a recording current waveform by the recording / reproducing amplifier 41. Bits are written in the user data area of the magnetic recording medium 34 by exciting the recording element of the magnetic head 31. On the contrary, the magnetic field leaked from the written bit is converted into an electrical signal by sensing by the reproducing element of the magnetic head 31, and the recording / reproducing amplifier 41 and the data encoding / decoding system 42 are suitable for the magnetic recording system. User data is reproduced through the waveform shaping / decoding process. What is important in this system is that the clock signal that gives the timing of polarity inversion in the recording current is independently generated in the controller 43 or its peripheral circuit, and is sent to the recording / reproducing amplifier. For this reason, if a patterned medium is used as the magnetic recording medium 34, it is very difficult to synchronize the pattern arrangement of the effective area and the timing of reversing the polarity of the recording current.

  Therefore, in this embodiment, as shown in FIG. 7, a clock reproduction head 15 for referring to the clock information track is newly mounted, and the reproduction signal from here is sent via the waveform shaper 49 to the clock signal of the recording / reproduction amplifier 41. The configuration was changed to supply as The recording / reproducing amplifier 41 uses the reproduction signal from the clock reproducing head 15 output from the waveform shaper 49 as a clock signal, and writes user data in synchronization with the clock signal. However, in actual device assembly, the average phase of the clock signal is adjusted by the learning function so that the recording current can be reversed at the timing when the effective area on the medium and the recording element are in the relative positional relationship most suitable for recording. A process for optimization was provided.

  An example of the optimization process by this learning function is shown in FIG. First, a track number is designated (S11), and the recording / reproducing head is set to that track (S12). Next, the servo sector of the track is read (S13), and the phase of the recording current is matched with the postamble of the servo sector (S14). Thereafter, recording is performed (S15), and the recorded signal is reproduced to measure the error rate (S16). If the error rate exceeds the reference value (determination in S17 is No), the recording current phase is changed (S18), and recording / reproduction is repeated, and the recording current phase is set so that the error rate is below the reference value. Ask. If the error rate is equal to or less than the reference value in the determination of step 17, the track number is changed (S19) and the same operation is repeated. In principle, the work is to optimize the phase difference between the postamble signal of the servo sector and the recording current for all tracks. However, if an effective area pattern is produced so that it may be set for each of a plurality of adjacent tracks, that is, for each zone, the assembly cost of the apparatus can be suppressed, so that a cheaper magnetic disk apparatus can be provided.

  Further, in order to improve the reliability of the magnetic disk device, the clock reproducing head 15 is used as a medium when the power of the device is turned off or when a large impact is expected by a monitor such as an acceleration sensor provided separately in the device. Means for retracting from the surface was provided. Specifically, as shown in FIG. 15A, a load / unload pin 17 is disposed in the vicinity of the suspension arm 16 of the clock reproducing head 15. The load / unload pin 17 is located away from the suspension arm 16 of the clock reproducing head 15 when the magnetic disk device is operating normally. The clock reproducing head 15 is loaded on the magnetic recording medium 34. Has been. On the other hand, when the power supply of the magnetic disk device is shut down or when an acceleration sensor installed in the magnetic disk device detects a drop, the load / unload pin 17 is connected to the suspension / unload pin 17 as shown in FIG. The arm 16 is pushed up, and the clock reproducing head 15 is unloaded from the magnetic recording medium 34. With this configuration and function, the reliability of not only the recording / reproducing head but also the clock reproducing head 15 is ensured, and the magnetic disk device to which the present invention is applied can be applied to various digital devices such as mobile devices. It was.

According to the present embodiment, it becomes possible to reflect the deviation of the recording timing due to the rotation unevenness of the disk 34 to the polarity inversion timing of the recording current with high accuracy, and the bit of user data to the effective area 21 on the pattern medium 34 with high accuracy. I can write now. FIG. 8 is a diagram showing the dependence of the bit error rate on the linear recording density in the magnetic disk device thus realized. For comparison, data in the apparatus of FIG. 6 that does not refer to the clock information track is also shown. As can be seen from FIG. 8, the bit error rate is improved by 2 digits or more by referring to the clock information track, and even at a very high linear recording density of 2 MBPI (MBPI: 10 6 per inch). A practical characteristic of about 10 ⁻⁴ was obtained. As a result, it was possible to realize a linear recording density of 2 MBPI and a track density of 250 kTPI (kTPI: the number of tracks is 10 to the third power), that is, a surface recording density of 500 gigabits per square inch. As a result, a small-sized and large-capacity magnetic disk device can be provided at low cost.

  In the above embodiment, since a plurality of recording media are mounted on one HDD, a clock information track is formed on each medium surface, and the number of clock reproducing heads for reproducing the same is the same as the number of medium surfaces. It was necessary. Here, one of the clock information tracks can be reproduced by one clock reproducing head and used for recording on another medium surface. However, in that case, it is inevitable that a certain degree of synchronization error will occur depending on the accuracy when the recording medium is fixed to the spindle rotation shaft. When this was tried in the apparatus of this example, the bit error rate deteriorated about twice, but no significant effect was seen on the performance of the apparatus.

  FIG. 9 is a process cross-sectional view illustrating another example of the pattern medium manufacturing method of the present invention. First, a magnetic recording material layer 61 is formed on a clean substrate 60 that has been cleaned in advance, and then lithography and development of the mask material 62 (FIG. 9A) and etching (FIG. 9B) are performed as in the first embodiment. ), Patterning the magnetic recording material layer 61 itself through a process consisting of peeling cleaning (FIG. 9C), and then forming a protective film 63 as shown in FIG. 9D. In this case, the portion where the recording material 61 is etched becomes the ineffective region 22, and the portion shielded by the mask material and not etched becomes the effective region 21. Also in the present embodiment, as in the first embodiment, a protective film 63 may be attached after a smooth surface is formed through filling with a non-magnetic material 64 by an appropriate flattening process (FIG. 9E). )). In the case of etching a magnetic metal such as a recording material, the mask material 62 includes Ta, Ti, TiN, alumina, silicon oxide in addition to the resist and SOG and other thermo- and photo-curing materials described in the first embodiment. By using a so-called hard mask together, the processing accuracy can be greatly improved. Further, since a part of these hard mask materials adheres to the etched side wall, the recording material is prevented from being corroded, and a magnetic recording medium and an HDD having excellent long-term reliability can be manufactured.

  Also in this embodiment, the pattern of the user data area 11 for recording / reproducing user data and the pattern of the clock information track 13 are formed simultaneously. As a result, the fluctuation in the recording timing in the user data area 11 due to the rotation irregularity of the recording medium and the fluctuation in the clock signal generated from the clock information track 13 can be exactly matched, and the recording operation on the pattern medium can be performed with high accuracy. Is guaranteed.

  The previous embodiments are exactly the same in the in-plane recording method in which the direction of magnetic anisotropy of the recording material is substantially parallel to the substrate surface and in the perpendicular recording method in which the direction of magnetic anisotropy is substantially perpendicular to the substrate surface. It is. By the way, in the perpendicular recording system, there is known a structure including a so-called perpendicular magnetic recording layer 65 having a high coercive force, a soft magnetic backing layer 66 (SUL) having a high magnetic permeability, and an intermediate layer 67 separating them. Yes. In the case of this two-layer perpendicular magnetic recording medium, the etching corresponding to FIG. 9B is performed only on the recording layer 65 or only the recording layer 65 and the intermediate layer 67 as shown in FIG. 9F. It is more desirable.

  Using the patterned medium thus produced, a magnetic disk device similar to that of Example 1 was constructed. As a result, the track density could be increased by 20% compared to Example 1, and about 600 gigabits per square inch. The high recording density was achieved.

  FIG. 10 is a conceptual diagram showing an example of improving the pattern arrangement of the clock information track. The boundary position 85 between the effective area 21 and the ineffective area 22 in the clock information track fluctuates in the head traveling direction within the accuracy of the manufacturing process. For this reason, the clock signal also includes jitter in the same way as a normal user data reproduction signal. Since this jitter is naturally included in the clock signal supplied to the recording / reproducing amplifier 41, the write current synchronization accuracy is degraded. Therefore, some device is required to realize high-precision synchronization.

  In this embodiment, the clock information track is divided into three in the radial direction as shown in FIG. If this is reproduced by a single clock reproducing head, the substantial signal wavelength of the clock signal does not change. At this time, even if the effective reproducing track width of the clock reproducing head is smaller than the entire width of the clock signal track as indicated by 38 in FIG. Then, since the position of each divided effective area-ineffective area boundary (for example, 86a, 86b, 86c) fluctuates independently, if this is simultaneously referenced by one clock reproducing head, the result of averaging is the result. It can be expected that the jitter of the clock signal will decrease. Referring to FIG. 11, it was found that the jitter amount of the clock signal was reduced to about half by first dividing the clock information track into two, and the jitter amount was monotonously decreased as the number of divisions was increased. Correspondingly, it was found that the bit error rate in the user data is improved according to the number of divisions as shown in FIG.

  From the examination of this embodiment, the bit error rate was improved by dividing the clock information track into two or more, and the linear recording density could be increased by 40% compared to the first embodiment. As a result, it was possible to achieve a high recording density of about 700 gigabits per square inch.

  FIG. 13A is a cross-sectional view schematically showing the magnetization state of each effective region of the clock information track in the above embodiment. It is necessary to always have a magnetization transition between the effective regions, and the magnetization is alternately arranged vertically. Such a magnetized state can be realized by an appropriate initialization apparatus equipped with a recording element in the pattern medium manufacturing process. However, writing such magnetization on all recording media is a major issue in reducing manufacturing costs.

  Therefore, in this embodiment, as shown in FIG. 13B, the effective areas are arranged with a period twice that of the originally required clock signal. At this time, a clock signal obtained by reproducing the pattern of FIG. 13A is shown in FIG. 13C, and a clock signal obtained by reproducing the pattern of FIG. 13B is shown in FIG. As shown in FIG. 13D, the maximum voltage amplitude of the clock signal reproduced from the pattern shown in FIG. 13B is half that of the clock signal reproduced from the pattern shown in FIG. Gives exactly the same results. Since the clock information track in FIG. 13B has a low pattern density, the manufacturing yield can be increased. Also, since the initialization of magnetization can be performed in a very short time by applying an external magnetic field, the manufacturing cost of the recording medium can be greatly reduced without sacrificing performance. As a result, a large capacity and highly reliable magnetic disk apparatus could be manufactured at low cost.

INDUSTRIAL APPLICABILITY The present invention is applied to not only a small magnetic disk device having a form factor of 3.5 inches or less using a glass substrate or an aluminum substrate but also a so-called removable type external storage device capable of separating a recording medium and a recording / reproducing mechanism. Is also possible. The recording method is effective in any of the in-plane recording method, the vertical recording method, and the perpendicular recording method using a so-called two-layer medium. Further, since it can be easily combined with the heat-assisted recording method, it can also be applied to a magnetic disk device having a higher recording density of 1 Tb / In ² class. You may use for the magnetic disc apparatus which has a some recording / reproducing head with respect to the recording medium 1 surface.

The schematic diagram of the recording state in the conventional magnetic recording medium. The schematic diagram of the recording state in a pattern medium. 1 is a schematic plan view of a magnetic recording medium according to the present invention. Process sectional drawing which shows an example of the manufacturing method of a pattern medium. 1 is a schematic plan view of a magnetic disk device incorporating a pattern medium. The connection diagram of each element in the conventional magnetic disk apparatus. FIG. 3 is a connection diagram of each element in the magnetic disk device of the present invention. The figure which compared the bit error rate when not referring with the clock information track. Process sectional drawing which shows the other example of the preparation methods of a pattern medium. The conceptual diagram which showed the example of a pattern arrangement | sequence of a clock information track. The figure which shows the relationship between a clock signal jitter amount and the number of clock information track divisions. The figure which shows the relationship between a bit error rate and the number of clock information track divisions. A sectional view showing composition of a clock information track, and a figure showing a clock signal waveform which reproduced these. Flow chart showing learning process for recording timing optimization FIG. 3 is a schematic cross-sectional view showing a load / unload operation of a clock reproducing head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... User data area, 12 ... Servo area, 13 ... Clock information track, 15 ... Clock reproduction head, 21 ... Effective area, 22 ... Invalid area, 31 ... Magnetic head, 33 ... Actuator, 34 ... Magnetic recording medium, 35 ... Spindle motor, 36 ... positioning mechanism, 41 ... recording / reproducing amplifier, 42 ... data encoding / decoding system, 43 ... controller, 44 ... external interface, 45 ... mechanism control system

Claims (18)

A substrate and a recording film formed on the substrate;
An invalid area that does not hold data, and a plurality of effective areas that are arranged in the invalid area in accordance with a predetermined pattern and hold data in units of one recording bit,
A user data area including a plurality of effective areas and a servo area are provided,
A patterned medium comprising a clock information track configured to include a plurality of the effective areas on the outermost peripheral side of the substrate and providing a clock when data is written to the user data area.   2. The patterned medium according to claim 1, wherein the clock information track is a substantially single circumferential track having a constant linear recording density.   3. The pattern medium according to claim 2, wherein each of the effective areas included in the clock information track is divided into a plurality in the radial direction of the substrate.   2. The pattern medium according to claim 1, wherein the effective area included in the clock information track is formed in the same process as the effective area included in the user data area.   2. The pattern medium according to claim 1, wherein the effective areas included in the clock information track are all in the same direction.   2. The patterned medium according to claim 1, wherein the recording film is a perpendicular magnetic recording film, and has a soft magnetic backing layer continuously provided in an in-plane direction between the substrate and the recording film. Pattern medium to do. A plurality of substrates each having a substrate and a recording film formed on the substrate, each of which is arranged in an invalid area that does not hold data and is isolated in accordance with a predetermined pattern in the invalid area and holds data in units of one recording bit Effective data areas, a user data area including a plurality of effective areas, and a servo area are provided, and a plurality of effective areas are included on the outermost peripheral side of the substrate, and data to the user data area is provided. A patterned medium having a clock information track for providing a clock at the time of writing;
A medium driving unit for driving the patterned medium;
A magnetic head for recording / reproducing user data in the user data area of the pattern medium;
A magnetic head driving unit for positioning the magnetic head at a desired position of the patterned medium;
A signal processing unit for processing the user data;
A clock reproducing head for referring to the clock information track of the pattern medium,
The magnetic disk device according to claim 1, wherein the signal processing unit writes the user data in synchronization with a clock signal reproduced by the clock reproducing head.   8. The magnetic disk apparatus according to claim 7, wherein the clock information track is substantially one circumferential track having a constant linear recording density.   8. The magnetic disk apparatus according to claim 7, wherein each effective area included in the clock information track is divided in a radial direction of the pattern medium.   8. The magnetic disk apparatus according to claim 7, wherein the effective area included in the clock information track is formed in the same process as the effective area included in the user data area. .   8. The magnetic disk apparatus according to claim 7, wherein the effective areas included in the clock information track are all in the same direction.   8. The magnetic disk apparatus according to claim 7, wherein the relative phase relationship between the recording element of the magnetic head and the effective area is optimal when the average phase of the signal reproduced from the clock information track by the clock reproducing head is reversed. A magnetic disk device having a function of learning to become   8. The magnetic disk device according to claim 7, wherein the clock reproducing head has means for retreating from a floating state when an external impact is applied to the disk device or when the power of the device is turned off. Magnetic disk unit. Forming a mask material layer on the substrate;
Forming a mask by simultaneously patterning a pattern of a user data area on the mask material layer and a pattern of a clock information track that gives a clock when writing data to the user data area; and
Etching the substrate using the mask;
Removing the mask;
And a step of forming a recording layer on the substrate after the etching process.   15. The method of manufacturing a patterned medium according to claim 14, wherein the clock information track is substantially one circumferential track having a constant linear recording density formed on the outermost peripheral side of the substrate. Pattern medium manufacturing method. Forming a magnetic recording material layer on the substrate;
Forming a mask material layer on the magnetic recording material layer;
Forming a mask by simultaneously patterning a pattern of a user data area on the mask material layer and a pattern of a clock information track that gives a clock when writing data to the user data area; and
Etching the magnetic recording material layer using the mask;
A pattern medium manufacturing method comprising: removing the mask.   17. The method of manufacturing a patterned medium according to claim 16, wherein the clock information track is substantially one circumferential track having a constant linear recording density formed on the outermost periphery side of the substrate. Pattern medium manufacturing method.   17. The method for manufacturing a patterned medium according to claim 16, wherein the magnetic recording material is a perpendicular magnetic recording material, and a soft magnetic backing layer is formed before forming the magnetic recording material layer. Method.

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