JP2006024255A - Method for manufacturing magnetic disk, magnetic recording/reproducing device, and method for manufacturing magnetic recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic disk capable of enhancing the uniformity of the magnetization reversal length of a signal on the whole surface of a magnetic disk, and improving tracking accuracy, a magnetic recording/reproducing device, and a method for manufacturing the magnetic recording/reproducing device. <P>SOLUTION: The method includes the step of forming the shape pattern of a ferromagnetic material corresponding to an information signal as a master information carrier, and recording the information signal corresponding to the shape pattern as magnetization signal in a magnetic disk. The shape pattern is provided for forming a plurality of segments 17a to 17b by recording the magnetization information so that a shortest magnetization reversal length is gradually increased according as the distance of a radial direction from the center of the magnetic disk is larger. As for two adjacent segments, among the magnetization reversal lengths of segments on a disk outer peripheral side, a shortest magnetization reversal length on a disk innermost peripheral side is smaller than the shortest magnetization reversal length of a disk outermost peripheral side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a magnetic disk in which a predetermined information signal is recorded in advance using a master information carrier, a magnetic recording / reproducing apparatus equipped with a magnetic disk manufactured by the manufacturing method, and a method for manufacturing the same.

In recent years, magnetic recording / reproducing apparatuses tend to have a higher recording density in order to realize a small size and a large capacity. In the field of hard disk drives, which are typical magnetic storage devices, devices having a surface recording density exceeding 60 Gbit / in ² (93 Mbit / mm ² ) have already been commercialized, and soon, the surface recording density is 100 Gbit / in ² ( 155 Mbit / mm ² ) is recognized as a rapid technological advance to the extent that the practical application is discussed.

  The technical background that made it possible to achieve such high recording density is also due to the improvement in medium recording performance, head / disk interface performance, and the increase in linear recording density due to the emergence of new signal processing methods such as partial response. . However, in recent years, the increasing tendency of the track density greatly exceeds the increasing tendency of the linear recording density, which is a main factor for improving the surface recording density. This is based on the contribution from the practical use of a giant magnetoresistive head (GMR head) that is much more excellent in reproduction output performance than conventional induction magnetic heads. At present, with the practical use of GMR heads, it is possible to reproduce a track width signal of 1 μm or less with good S / N. As the head performance further improves, the track pitch is expected to become even smaller.

  Now, in order for the head to accurately scan such a narrow track and reproduce the signal with good S / N, the servo tracking technology of the head plays an important role. In order to perform servo tracking, the current hard disk drive is an area in which a servo signal for tracking, an address information signal, a reproduction synchronization signal, etc. are recorded at regular angular intervals within one round of the disk, that is, 360 degrees. Hereinafter, the servo track area is provided. The magnetic head can accurately scan the track while confirming and correcting the position of the head by reproducing the signals of these servo track areas at regular intervals.

  The tracking servo signal, the address information signal, the reproduction synchronization signal, and the like serve as reference signals for the head to accurately scan the track, so that accurate positioning accuracy is required at the time of recording. In the current hard disk drive, after the disk is incorporated into the drive, the tracking servo signal, address information signal, reproduction synchronization signal, etc. are recorded by a magnetic head that is strictly position-controlled using a dedicated servo recording device. It has been broken.

  Here, the recording method using the magnetic head using the dedicated servo recording apparatus as described above has the following problems. That is, since the recording by the magnetic head is a linear recording based on the relative movement between the head and the medium, a signal recording is performed over the entire surface of the magnetic disk while strictly controlling the position of the magnetic head using a dedicated servo recording device. So it took a lot of time.

  Therefore, it is required to prepare the necessary number of servo recording devices according to the number of hard disk drives produced. Such a dedicated servo recording device is a very expensive facility. Further, since a servo recording device is used, signal recording has to be performed in a clean room with the drive housing opened. For this reason, in order to install a large number of servo recording apparatuses, the capital investment for installing a clean room has increased, which has caused a significant increase in cost.

  Under such circumstances, the following methods have been proposed. For example, Patent Document 1 proposes a method using a master information carrier. The master information carrier is formed by forming a magnetic part made of a ferromagnetic material in a pattern shape corresponding to an information signal on the surface of a base. In the method proposed in Patent Document 1, the surface of the master information carrier is brought into contact with the surface of a sheet-like or disk-like magnetic recording medium on which a ferromagnetic thin film or a ferromagnetic powder coating layer is formed. Then, by applying a predetermined external magnetic field, a magnetic pattern having a pattern shape corresponding to the information signal formed on the master information carrier is magnetically transferred and recorded on the magnetic recording medium.

  In this method, a magnetic field corresponding to the ferromagnetic thin film pattern of the master information carrier is magnetically transferred and recorded on the magnetic recording medium by a recording magnetic field generated from the ferromagnetic thin film on the surface of the master information carrier magnetized in one direction. It will be. That is, by forming a ferromagnetic thin film pattern corresponding to a tracking servo signal, an address information signal, a reproduction synchronization signal, etc. on the surface of the master information carrier by a photolithography technique or the like, these servo track areas are formed on the magnetic recording medium. A signal can be recorded as magnetization information.

  Whereas recording by a conventional magnetic head is dynamic linear recording based on relative movement between the head and the medium, the recording of Patent Document 1 is static surface recording that does not involve relative movement between the master information carrier and the medium. It is. Due to such characteristics, the technique of Patent Document 1 can exhibit the following extremely effective effects on the problems in the conventional method.

  In other words, because of the collective surface recording, the time required for signal recording in the servo track area is very short compared to the recording method using a conventional magnetic head. In addition, an expensive servo recording apparatus for performing recording while strictly controlling the position of the magnetic head is unnecessary, and a vast clean room for installing the servo head is also unnecessary. For this reason, productivity in signal recording can be greatly improved and production cost can be reduced.

  Further, since the method of Patent Document 1 is a method of magnetic transfer recording using shape information as magnetization information, various patterns that cannot be recorded by a magnetic head can be recorded. That is, when a magnetic head is used, a signal having a track width different from the recording track width unique to the magnetic head cannot be recorded, and azimuth in a direction inclined with respect to the recording gap or reproducing gap of the magnetic head. It is also impossible to record a magnetization pattern having a corner. On the other hand, in the method of Patent Document 1, since a shape pattern made of a ferromagnetic material can be freely designed, even a magnetization pattern that cannot be recorded by a magnetic head can be recorded easily.

  Further, according to the method of Patent Document 2, by using the method of Patent Document 1, a magnetic pattern that cannot be recorded by a magnetic head is recorded according to the use of various signals recorded on the magnetic disk, and each signal is recorded. It is possible to improve the target performance. For example, by using a tracking servo signal pattern having an azimuth angle in a direction inclined with respect to the reproduction gap of the magnetic head, it is possible to detect and track the phase change of the signal accompanying the radial displacement of the magnetic disk. It becomes. For this reason, tracking accuracy can be improved as compared with the conventional method using amplitude detection.

  By the way, in order to use the magnetic transfer recording method described in Patent Document 1 or Patent Document 2, it is necessary to accurately form a shape pattern of a ferromagnetic material corresponding to an information signal to be recorded using a lithography technique. It is. However, the higher the density of the signal to be recorded, that is, the smaller the magnetization reversal length in the recording magnetization pattern, the more necessary to form a corresponding fine ferromagnetic material shape pattern. For this reason, there has been a problem that the lithography process becomes technically more difficult and requires a high-performance apparatus, resulting in high costs.

  The recording density of the tracking servo signal is lower than that of the user data signal. However, in recent hard disk drives, the magnetization reversal length is as small as about 0.1 μm. It is not easy to form such a fine pattern in a wide area corresponding to the magnetic disk surface even by using the most advanced lithography technology for semiconductors.

  On the other hand, if the signal density in the servo track region is designed to be relatively small, that is, the magnetization reversal length is designed to be relatively large, the lithography process becomes easy. However, in this case, the proportion of the servo track area on the magnetic disk surface becomes large and the user data area is sacrificed. As a result, the storage capacity of the magnetic recording / reproducing apparatus is reduced.

  Patent Document 3 proposes a method for solving such a problem. In the method of Patent Document 3, the first servo track area including the first tracking servo signal is first recorded on the magnetic disk using the magnetic transfer recording method of Patent Document 1 and Patent Document 2, and then mounted on the hard disk drive. To do. Subsequently, referring to the first tracking servo signal, the magnetic head mounted on the hard disk drive is positioned, and the second servo track area including the second tracking servo signal is recorded by this magnetic head.

  In other words, the technique of Patent Document 3 refers to the servo track area signal recorded by the method of Patent Document 1 or Patent Document 2, and the magnetic head mounted on the hard disk drive records the signal at a higher density. This is a technique of correcting (hereinafter referred to as “self-servo recording”).

  Also in the method of Patent Document 3, an expensive servo recording apparatus is unnecessary as in the method of Patent Document 1. On the other hand, in the method of Patent Document 3, extra time is required for the self-servo recording process, but this process can be performed in a relatively small space outside the clean room after the drive housing is sealed. No capital investment is required. Further, since the hard disk drive itself can automatically perform recording under computer management without the need for manpower, as in the method of Patent Document 1, compared to the conventional method using a dedicated servo recording device, The improvement in productivity and cost merit becomes large.

According to the method of Patent Document 3, a phase detection pattern as disclosed in Patent Document 2 can be used as the first tracking servo signal to be magnetically transferred and recorded. On the other hand, the second tracking servo signal is recorded by a magnetic head mounted on the hard disk drive. Since it is difficult to record a phase detection pattern as disclosed in Patent Document 2 using a magnetic head, a conventional amplitude detection pattern is used as the second tracking servo signal. It is common.
JP 10-40544 A JP-A-11-144218 Japanese Patent Laid-Open No. 2001-243733

  However, as a result of examining the performance of the tracking servo signal by phase detection recorded by the magnetic transfer recording method proposed in Patent Document 2 or Patent Document 3, the position detection accuracy of the magnetic head varies depending on the position of the magnetic disk. In particular, it has been found that there is a tendency that tracking accuracy tends to be lower on the outer peripheral side of the magnetic disk than on the inner peripheral side.

  That is, this phenomenon suggests that the performance of the hard disk drive, such as the access speed, may change depending on the position on the magnetic disk where the signal is recorded / reproduced.

  In the method of Patent Document 2, since the tracking servo signal recorded by magnetic transfer becomes the final tracking servo signal, it is preferable that the above-mentioned phenomenon be solved.

  On the other hand, in the method of Patent Document 3, the first tracking servo signal based on the phase detection recorded by magnetic transfer is rewritten to the second tracking servo signal by self-servo recording using a magnetic head. In this case, a positioning error occurs when the magnetic head is positioned with reference to the first tracking servo signal during self-servo recording.

  Since this positioning error is reflected as a writing position error in the second tracking servo signal which is the final tracking servo signal, it is preferable that the positioning error be solved in the same manner.

  The present invention solves the conventional problem as described above, and can improve the uniformity of the magnetization reversal length of the signal over the entire surface of the magnetic disk and improve the tracking accuracy. An object of the present invention is to provide a magnetic recording / reproducing apparatus and a method for manufacturing the magnetic recording / reproducing apparatus.

  In order to achieve the above object, a method of manufacturing a magnetic disk according to the present invention forms a shape pattern of a ferromagnetic material corresponding to an information signal on a surface of a substrate as a master information carrier, and the master information carrier is used as a surface of a magnetic disk. A magnetic disk manufacturing method comprising a step of recording an information signal corresponding to the shape pattern as magnetization information on the magnetic disk by applying an external magnetic field in contact with the shape pattern, wherein the shape pattern includes the magnetization pattern A shape pattern in which a plurality of segments are formed adjacent to each other in the radial direction of the magnetic disk by recording information so that the shortest magnetization reversal length increases as the radial distance from the center of the magnetic disk increases. As for the two segments adjacent to each other in the radial direction of the magnetic disk, the segments are the same. Among the magnetization reversal lengths of the segments on the outer peripheral side of the magnetic disk, the shortest magnetization reversal length on the inner peripheral side of the magnetic disk is the longest of the magnetization reversal lengths of the segments on the inner peripheral side of the magnetic disk. It is smaller than the shortest magnetization reversal length on the side.

  The magnetic recording / reproducing apparatus of the present invention is a magnetic recording / reproducing apparatus equipped with a magnetic disk in which an information signal is recorded in advance, and the magnetic disk has a shortest magnetization reversal length in the radial direction from the center of the magnetic disk. As the distance increases, a plurality of segments are formed adjacent to each other in the radial direction of the magnetic disk. The plurality of segments are the two segments adjacent to each other in the radial direction of the magnetic disk. Of the magnetization reversal lengths of the segments on the outer circumferential side of the disk, the shortest magnetization reversal length on the inner circumferential side of the magnetic disk is the longest of the magnetization reversal lengths of the segments on the inner circumferential side of the magnetic disk. It is characterized by being smaller than the shortest magnetization reversal length on the side.

  Next, a method for manufacturing a magnetic recording / reproducing apparatus according to the present invention is a method for manufacturing a magnetic recording / reproducing apparatus having a magnetic disk on which information signals are recorded in advance, and corresponds to the first tracking servo signal on the substrate surface. Forming a shape pattern of the ferromagnetic material as a master information carrier, and applying the external magnetic field by bringing the master information carrier into contact with the surface of the magnetic disk, whereby the first tracking object corresponding to the shape pattern A step of recording a servo signal as magnetization information on the magnetic disk, and the shape pattern increases as the distance in the radial direction from the center of the magnetic disk increases due to the recording of the magnetization information. A shape pattern in which a plurality of segments are formed adjacent to each other in the radial direction of the magnetic disk, and the plurality of segments As for two segments adjacent in the radial direction of the magnetic disk, of the magnetization reversal lengths of the segments on the outer peripheral side of the magnetic disk, the shortest magnetization reversal length on the inner peripheral side of the magnetic disk is the magnetic reversal length. The magnetization reversal length of the segment on the inner peripheral side of the disk is shorter than the shortest magnetization reversal length on the outer peripheral side of the magnetic disk, and after the magnetic disk is mounted on the magnetic recording / reproducing apparatus, the first Recording a second tracking servo signal different from the first tracking servo signal by the magnetic head while positioning the magnetic head mounted on the magnetic recording / reproducing apparatus with reference to the tracking servo signal. It is provided with.

  According to the present invention, it is possible to improve the uniformity of the magnetization reversal length of the signal over the entire surface of the magnetic disk and improve the tracking accuracy.

  According to the method for manufacturing a magnetic disk and the magnetic recording / reproducing apparatus of the present invention, a plurality of segments are formed, and the magnetization reversal length is temporarily reduced for each segment as it goes to the outer peripheral side of the magnetic disk. The uniformity of the magnetization reversal length of the signal can be improved over the entire disk surface, and the tracking accuracy can be improved.

  Further, according to the method of manufacturing the magnetic recording / reproducing apparatus of the present invention, the previously recorded tracking servo signal can be automatically re-recorded into a higher-density signal by the magnetic recording / reproducing apparatus itself. For this reason, a clean room and manpower can be omitted, productivity can be improved, and production costs can be reduced.

  In the magnetic disk manufacturing method of the present invention, it is preferable that the information signal includes a tracking servo signal.

  The tracking servo signal preferably includes a phase detection signal pattern that can identify a radial position of the magnetic disk by detecting a phase change of the reproduction signal accompanying a radial displacement of the magnetic disk.

  The tracking servo signal is preferably a concentric circular signal pattern, and the signal pattern is preferably recorded by decentering the signal pattern center and the magnetic disk center. According to this configuration, it is possible to more reliably reproduce the information signal in the signal discontinuous region at the boundary between the segments.

  Of the plurality of segments, an innermost segment in the radial direction of the magnetic disk is formed between an inner peripheral crash stop position of the magnetic disk and a user data area innermost position, It is preferable to form it separately from the segment in the user data area. According to this configuration, since many signals having a relatively small magnetization reversal length with relatively good tracking accuracy can be used in the user data region, the tracking accuracy in the user data region can be relatively improved.

  In the magnetic recording / reproducing apparatus, the information signal preferably includes a tracking servo signal.

  The tracking servo signal preferably includes a phase detection signal pattern that can identify a radial position of the magnetic disk by detecting a phase change of the reproduction signal accompanying a radial displacement of the magnetic disk.

  The tracking servo signal is preferably a concentric circular signal pattern, and the signal pattern center and the magnetic disk center are preferably eccentric. According to this configuration, it is possible to more reliably reproduce the information signal in the signal discontinuous region at the boundary between the segments.

  Of the plurality of segments, an innermost segment in the radial direction of the magnetic disk is formed between an inner peripheral crash stop position of the magnetic disk and a user data area innermost position, It is preferably formed separately from the segment in the user data area. According to this configuration, since many signals having a relatively small magnetization reversal length with relatively good tracking accuracy can be used in the user data region, the tracking accuracy in the user data region can be relatively improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
First, the information signal magnetic transfer recording method according to the first embodiment of the present invention will be described. FIG. 1 shows a schematic diagram of a recording apparatus for performing magnetic transfer recording of an information signal according to the present embodiment. In FIG. 1, a hard disk 1 which is a magnetic disk is a donut disk-shaped disk having a center hole 1a. The hard disk 1 is configured by forming a ferromagnetic thin film mainly composed of Co or the like on the surface of a nonmagnetic substrate by a sputtering method.

  A disk-shaped master information carrier 2 is disposed so as to be in contact with the surface of the ferromagnetic thin film of the hard disk 1. The master information carrier 2 is generally larger in diameter than the hard disk 1, and a signal area 2 a is provided on the surface on the side in contact with the hard disk 1. The signal area 2a is formed of a ferromagnetic thin film having a fine array pattern shape corresponding to an information signal to be magnetically transferred and recorded on the hard disk 1.

  The hard disk 1 is held by a disk holder 3. A chuck part 3 a for positioning and holding the hard disk 1 is provided at the tip of the disk holder 3. Further, a suction hole 3 b is provided inside the disk holder 3, the suction hole 3 b communicates with the central hole 1 a of the hard disk 1, and one end is connected to the exhaust duct 4.

  An exhaust device 5 is attached to the end of the exhaust duct 4. When the exhaust device 5 is started, the exhaust duct 4 and the suction hole 3 b of the disc holder 3 are connected to each other between the hard disk 1 and the master information carrier 2. The space between them is in a negative pressure state. As a result, the master information carrier 2 is attracted to the hard disk 1 side and is superposed on the master information carrier 2 with the hard disk 1 positioned.

  At this time, a slight gap groove is formed on the surface of the master information carrier 2 except for the signal area 2a, and air between the hard disk 1 and the master information carrier 2 can be sucked through the gap groove.

  The magnetizing head 6 is for applying an external magnetic field required for transfer recording from the master information carrier 2 to the hard disk 1. The magnetic thin film pattern corresponding to the information signal formed on the master information carrier 2 is magnetized by the magnetic field applied from the magnetizing head 6, and the magnetic flux corresponding to the magnetic thin film pattern generated from the magnetic thin film pattern corresponds to the shape of the ferromagnetic thin film pattern. The recorded information signal is recorded.

  FIG. 2 shows a perspective view of an example of the magnetizing head 6. The magnetizing head 6 shown in FIG. 2 has a magnetic core half 6b made of a ferromagnetic material having a winding 6a and a magnetic core half 6c also made of a ferromagnetic material facing each other. An annular magnetic circuit having a gap 6d is formed.

  By applying an exciting current to the winding 6a, a leakage magnetic flux from the magnetic core half 6b to the magnetic core half 6c is generated in the gap 6d as indicated by an arrow A. Further, the direction of the leakage magnetic flux generated in the gap 6d can be changed by changing the direction of the applied current. An arrow B indicates the direction of the internal magnetic flux generated in the magnetic core halves 6b and 6c when the leakage magnetic flux in the direction shown in FIG. 2 is generated.

  FIG. 3 is a plan view showing the shape of the gap 6d of the magnetizing head 6 shown in FIG. The gap 6d has the same arc shape as the orbit when the recording / reproducing magnetic head mounted on the hard disk drive performs tracking scanning on the surface of the magnetic disk on the surface facing the master information carrier 2.

  Therefore, the direction of the magnetic field generated in the gap 6d is always perpendicular to the tracking scanning trajectory, and the ferromagnetic thin film of the master information carrier 2 is magnetized in a direction perpendicular to the tracking scanning direction of the recording / reproducing magnetic head in all tracks. Is done. That is, it is magnetized in the same direction as the head gap length direction of the recording / reproducing magnetic head.

  Next, a configuration example of the master information carrier 2 will be described. FIG. 4 is a plan view schematically showing an example of the master information carrier 2. As shown in FIG. 4, signal regions 2 a are formed substantially radially on one main surface of the master information carrier 2, that is, the surface that contacts the ferromagnetic thin film surface of the hard disk 1.

  Fig.5 (a) is the enlarged view which showed the C section of FIG. 4 typically. The shape of the shape pattern formed by the magnetic part 2 b corresponds to the information signal recorded on the magnetic disk 1, and the position of the shape pattern is the information signal on the magnetic disk 1 when it overlaps the magnetic disk 1. Corresponds to the position where is recorded. In the example of FIG. 5 (a), the shape pattern corresponding to the information signal includes each signal area such as the reproduction synchronization signal 7, the servo address mark 8, the address information signal 9, and the tracking servo signals 10a and 10b in the head moving direction. That is, they are sequentially arranged in the track length direction.

  Of these shape patterns, the tracking servo signals 10a and 10b are tracking servo signal patterns having an azimuth angle in a direction inclined with respect to the reproduction gap of the magnetic head. This shape pattern is a phase detection pattern capable of performing tracking by detecting a phase change of a signal accompanying a radial displacement of the magnetic disk.

  The master information pattern shown in FIG. 5A is an example, and the configuration and arrangement of the master shape information pattern are appropriately determined according to the configuration, purpose, and use of the information signal recorded on the magnetic disk. Become.

  FIG.5 (b) is the enlarged view which showed typically the D section of Fig.5 (a). In FIG. 5B, the hatched portion is the magnetic portion 2b formed of a ferromagnetic thin film. The arrow shown in FIG. 5B indicates the direction in which the corresponding part of the magnetic disk is magnetized after the magnetic transfer recording is performed.

  In FIG. 5B, the width W1 of the magnetic part 2b in the head movement direction and the width W2 between the adjacent magnetic parts 2b in the head movement direction substantially correspond to the magnetization reversal length of the magnetization pattern recorded on the magnetic disk. ing. The width W1 and the width W2 are configured to increase as the disk radius increases, that is, toward the outer peripheral side of the magnetic disk. As a result, when the magnetic disk rotates at a constant rotational speed, the peripheral speed becomes faster on the outer peripheral side of the disk, so that the magnetization reversal length is proportional to the radius, so that substantially the same reproduction pulse interval is obtained on the time axis. It is configured.

  Here, the above-mentioned magnetization reversal length should be exactly called “the shortest magnetization reversal length at the radial position”. That is, when the shortest magnetization reversal length is t, the recorded information signal is generally composed of a combination of magnetization reversals having a magnetization reversal length that is an integral multiple of t (t, 2t, 3t, 4t, etc.). ing.

  Therefore, what is described here does not mean that the magnetization reversal length is configured to increase as the disk radius increases, even if all of the information signals having these various magnetization reversal lengths are considered. This means that the shortest magnetization reversal length t at a certain radial position is configured to increase as the radial distance from the disk center increases. That is, if the shortest magnetization reversal lengths are compared, the length increases as the radial distance from the disk center increases. However, since these contents can be easily understood by those skilled in the art with reference to this description, in the present specification, the contents of the definition of the magnetization reversal length described above are simply referred to as “magnetization reversal length”. Or “shortest magnetization reversal length”.

  FIG. 6 shows a partial cross-sectional view in the head movement direction of the formation region of the ferromagnetic thin film of the master information carrier 2 shown in FIG. As shown in FIG. 6, in the master information carrier 2, the ferromagnetic thin film 12 that forms the magnetic portion 2 b is embedded in the plurality of concave portions 11 a formed on the main surface 11 b of the base 11. The substrate 11 is a disc-shaped substrate formed of a nonmagnetic material such as a Si substrate, a glass substrate, or a plastic substrate. The main surface 11b is a surface on the side where the surface of the hard disk 1 contacts. The recess 11a is formed in a fine array pattern shape corresponding to the information signal.

  Here, in order to obtain good recording characteristics by uniformly adhering the hard disk 1 and the master information carrier 2 using the recording apparatus shown in FIG. 1, the surface 12a of the ferromagnetic thin film 12 is as flat as possible and It is preferable that the main surface 11b of the base body 11 is slightly protruded. For example, the protrusion amount of the ferromagnetic thin film 12 with respect to the major surface 11b of the base body 11 is preferably in the range of 5 nm to 100 nm from the viewpoint of durability of the master information carrier.

  As the ferromagnetic thin film 12, not only a hard magnetic material, a semi-hard magnetic material, and a soft magnetic material but also many kinds of magnetic materials can be used. In this case, in order to obtain better signal quality, it is preferable to use a soft magnetic thin film or semi-hard magnetic thin film having a relatively high magnetic permeability and to magnetize it uniformly by exciting it with an external magnetic field during magnetic transfer recording. . For example, Fe, Co, Ni—Fe alloy, Fe—Co alloy, or the like can be used.

  In order to generate a sufficient recording magnetic field regardless of the type of magnetic disk on which the master information signal is recorded, it is better that the saturation magnetic flux density of the magnetic material constituting the ferromagnetic thin film 12 is larger. In particular, for a magnetic disk having a high coercive force exceeding 2,000 oersted (159 kA / m) or a flexible disk having a large magnetic layer thickness, when the saturation magnetic flux density is 0.8 Tesla or less, sufficient recording cannot be performed. There is. For this reason, generally, a magnetic material having a saturation magnetic flux density of 0.8 Tesla or higher, preferably 1.0 Tesla or higher is used.

  The thickness of the ferromagnetic thin film 12 depends on the magnetization reversal length of the recorded information signal, the saturation magnetization, the coercive force, and the film thickness of the magnetic disk magnetic layer. For example, the magnetization reversal length is about 1 μm and the magnetic disk magnetic layer is saturated. When the magnetization is about 500 emu / cc (500 kA / m), the coercive force is 3000 oersted (239 kA / m), and the thickness is about 20 nm, it may be about 50 nm to 500 nm.

  Further, in such a magnetic transfer recording method, in order to obtain a good recording signal quality, a magnetic disk such as a hard disk is uniformly DC erased in the circumferential direction prior to magnetic transfer recording using a master information carrier. It is desirable to keep it.

  Next, a procedure for recording an information signal corresponding to the shape pattern formed on the master information carrier on the hard disk will be described. FIG. 7 is a perspective view showing a DC erasing process of the hard disk. FIG. 8 is a perspective view schematically showing the state of the hard disk that has been DC erased in the process of FIG. In the process shown in FIG. 7, in a state where the magnetizing head 6 is brought close to the hard disk 1, the hard disk 1 is rotated in parallel with the hard disk 1 with the central axis as the rotation axis. As a result, as indicated by the arrow in FIG. 8, the hard disk 1 is previously magnetized (DC erased) in one direction.

  Next, as shown in FIG. 1, the exhaust device 5 is started with the master information carrier 2 positioned and superimposed on the hard disk 1. Thus, the master information carrier 2 is sucked through the central hole 1a of the hard disk 1, and the surface of the master information carrier 2 on which the ferromagnetic thin film 12 is formed and the hard disk 1 are overlapped so as to be in close contact with each other.

  FIG. 9 is a perspective view showing a state where an information signal is magnetically transferred and recorded on the hard disk 1. The magnetic field applied by the magnetizing head 6 has a polarity opposite to that of the initial magnetization. In this state, the magnetizing head 6 is rotated in parallel with the master information carrier 2 with the center of the hard disk 1 held by the disk holder 3 as the center of rotation. A DC excitation magnetic field is applied to the master information carrier 2 while continuing this rotation. As a result, the ferromagnetic thin film 12 of the master information carrier 2 is magnetized and corresponds to the pattern shape of the magnetic part by the ferromagnetic thin film 12 in the predetermined information signal recording area 1b of the hard disk 1 superimposed on the master information carrier 2. An information signal is recorded. FIG. 10 shows a schematic diagram of the hard disk 1 in which the information signal is recorded in the information signal recording area 1b in the process shown in FIG. The arrows shown in FIG. 10 indicate the direction of magnetization remaining outside the information signal recording area 1 b of the hard disk 1.

  FIG. 11 is a cross-sectional view showing in detail the state of magnetization during information signal recording. As shown in FIG. 11, with the master information carrier 2 in close contact with the hard disk 1, a magnetic field is applied to the master information carrier 2 from the outside to magnetize the ferromagnetic thin film 12. As a result, an information signal is recorded on the magnetic recording layer 1 c made of a ferromagnetic thin film of the hard disk 1.

  That is, by using a master information carrier 2 formed by forming a ferromagnetic thin film 12 in a predetermined pattern shape on a nonmagnetic substrate 11, a digital information signal is magnetically transferred and recorded on a hard disk 1 which is a magnetic recording medium. be able to.

  Here, the magnetic transfer recording method will be described in more detail. FIG. 12 is a cross-sectional view schematically showing a series of processes of magnetic transfer recording of information signals as described above. 12A shows a DC erasing process of the hard disk 1, FIG. 12B shows an information signal magnetic transfer recording process using the master information carrier 2, and FIG. 12C shows an information signal magnetic transfer recording. The residual magnetization state of the hard disk 1 is shown. Each figure is a sectional view in the head moving direction, that is, in the track length direction of the information signal. When the magnetic recording medium is a hard disk, the track length direction of the information signal coincides with the disk circumferential direction.

  As shown in FIG. 12A, the magnetic recording layer 1c on the hard disk has a DC erasure magnetization 14 in a certain direction by the DC erasing magnetic field 13 prior to magnetic transfer recording of the information signal using the master information carrier. Uniform DC erasure. Next, as shown in FIG. 12B, the surface of the master information carrier 2 on which the ferromagnetic thin film is formed in the array pattern shape corresponding to the information signal is brought into close contact with the surface of the magnetic recording layer 1c on the hard disk, The ferromagnetic thin film 12 is excited by the DC excitation magnetic field 15. At this time, the polarity of the DC exciting magnetic field 15 is opposite to that of the DC erasing magnetic field 13. As a result, the magnetization 14 on the hard disk 1 is reversed by the leakage magnetic flux 16 only in the portion between the adjacent ferromagnetic thin films 12. As a result, after removing the master information carrier 2, a pattern of magnetization 14 corresponding to the array pattern shape of the ferromagnetic thin film formed on the master information carrier 2 can be recorded on the hard disk 1.

  Next, FIG. 13 shows the relationship between the disk radius and the shortest magnetization reversal length of the information signal in the present embodiment. The example of FIG. 13 is an example of a pattern that is magnetically transferred and recorded on a 2.5 inch hard disk. The disk outer diameter indicates the radius of the outer periphery of the hard disk, the disk inner diameter indicates the radius of the inner edge of the hard disk, and the user data area indicates a radius area in which user data is recorded.

  Further, in the hard disk drive, a stopper that mechanically restricts the movement of the magnetic head actuator in order to prevent the magnetic head from moving to the inner peripheral side more than necessary and contacting the spindle hub or the like to crash. Inner peripheral side crash stop). The illustrated inner peripheral side crash stop indicates the position of the magnetic head on the innermost peripheral side of the disk restricted by this stopper.

  Now, the information signal of the magnetic disk according to the present embodiment is recorded in a plurality of segments. In each segment, the shortest magnetization reversal length is configured to increase as the radial distance from the center of the magnetic disk increases. For example, in the configuration illustrated in FIG. 13, the information signal recording area 1b is composed of three segments: a first segment 17a, a second segment 17b, and a third segment 17c. Each segment is configured such that the magnetization reversal length increases as the radial distance from the center of the magnetic disk increases.

  In other words, when the magnetic disk rotates at a constant rotational speed, the peripheral speed is faster on the outer periphery side of the disk, so the magnetization reversal length is proportional to the radius in each segment, and approximately the same reproduction pulse interval on the time axis. Configured to get. On the other hand, the magnetization reversal length on the innermost circumferential side of each segment is configured to have the same value. That is, the magnetization reversal length on the innermost disk side of the segment adjacent to the disk outer periphery side of the segment is smaller than the magnetization reversal length on the outermost disk side of the segment. For example, the magnetization reversal length on the innermost circumference side of the second segment 17b disk is smaller than the magnetization reversal length on the outermost circumference side of the disk of the first segment 17a. The relationship between the second segment 17b and the third segment 17c is the same.

  At this time, from the viewpoint of simplifying the setting of the clock frequency in the hard disk drive, the magnetization reversal length of the disk on the outermost circumference side of a segment is determined by the segment adjacent to the disk outer circumference side of the segment (for example, the first segment 17a For the second segment 17b and the second segment 17b, the third segment 17c) is an integral multiple of the magnetization inversion length on the innermost disk side of the disk, or the segment adjacent to the disk outer periphery side of the segment. It is preferable to set the integral multiple of half of the magnetization reversal length on the innermost circumferential side of the disk. For example, in the configuration shown in FIG. 13, the magnetization reversal length on the outermost disk side of each segment is three times the half of the magnetization reversal length on the innermost disk side of the segment adjacent to the disk outermost side of that segment. It is configured as follows.

  In contrast, FIG. 16 shows the relationship between the disk radius and the shortest magnetization reversal length of the information signal in the conventional example. The information signal recording area 1b in the conventional example is integrally formed without being divided into a plurality of segments as in the present embodiment. The shortest magnetization reversal length is configured to increase monotonically in proportion to the radius of the magnetic disk.

  However, as a result of examining the performance of the tracking servo signal having such a conventional configuration, the position detection accuracy of the magnetic head varies depending on the position of the magnetic disk, and particularly on the outer peripheral side of the magnetic disk, the inner peripheral side There was a problem that the tracking accuracy tends to be lower than that of.

  As a result of repeatedly conducting various experiments and examinations on the problem of the conventional example, the present inventors have found that the tracking accuracy deterioration phenomenon as described above is due to the following action. The magnetization reversal length in the conventional configuration shown in FIG. 16 is about 0.35 micron on the innermost side of the disk, but increases with the increase in the disk diameter on the outermost side, and becomes 0.9 micron or more on the outermost side of the disk. Is also getting bigger. However, according to the study by the present inventors, the position detection accuracy in the tracking servo signal using the phase detection pattern increases as the tracking servo signal density increases, that is, as the magnetization reversal length decreases. It has been clarified that the larger the magnetization reversal length, the more the deterioration occurs.

  One of the factors is due to a coefficient when the phase difference detected from the tracking servo signal is converted into a distance. That is, as the magnetization reversal length is smaller, the distance corresponding to the unit phase difference is smaller, so that the head position can be detected with higher precision and accuracy. The effect of improving the position detection accuracy due to this factor is estimated to be proportional to the density of the tracking servo signal, that is, proportional to the reciprocal of the magnetization reversal length.

  That is, when the magnetization reversal length is halved, the head position detection accuracy is improved twice. On the contrary, the magnetization reversal length increases monotonously with the disk radius, and the tracking accuracy on the disk outer circumference side is greatly reduced in the conventional configuration of FIG. 16 where the outermost circumference of the disk is 2.5 times or more of the innermost circumference. become.

  Another factor to be considered relates to the detection S / N of the tracking servo signal. As shown in FIG. 5A, the tracking servo signals 10a and 10b using the phase detection pattern are signals that are periodically repeated with a constant magnetization reversal length. Each reproduced pulse included in this periodic signal has a factor that degrades the phase detection accuracy due to the influence of jitter, disturbance noise, etc., but the above factor is reduced by averaging the phase of each pulse. In addition, the phase detection accuracy can be improved.

  Here, if the magnetization reversal length of the tracking servo signal is small, more periodic signals can be recorded in the servo track area of the same size, so the signal can be increased by increasing the number of pulses to be averaged. It is possible to improve S / N and perform phase detection with high accuracy. The effect of improving the position detection accuracy due to this factor is estimated to be proportional to the square root of the density of the tracking servo signal, that is, proportional to the square root of the reciprocal of the magnetization reversal length. That is, if the magnetization reversal length becomes 1/4, the head position detection accuracy can be improved twice. However, in the conventional configuration of FIG. 16 in which the magnetization reversal length increases monotonously with the disk radius and is 2.5 times or more the innermost circumference at the outermost circumference of the disk, the tracking servo signal period on the outer circumference side of the disk is increased. There is no room for improvement, and it is not possible to improve tracking accuracy by actively utilizing this factor.

  On the other hand, in the configuration according to the present embodiment illustrated in FIG. 13, the magnetization reversal length on the innermost circumferential side of the disk is about 0.35 microns, which is equivalent to the conventional configuration in FIG. Including the magnetization reversal length on the outermost peripheral side of the disk can be suppressed to about 0.5 microns at the maximum.

  For this reason, compared with the conventional configuration, it is possible to suppress the deterioration of the tracking accuracy on the outer peripheral side of the disc, and to provide a configuration with excellent tracking accuracy uniformly and uniformly regardless of the radial position of the hard disk. For example, compared with the conventional configuration shown in FIG. 16, the tracking accuracy on the outermost peripheral side of the disk is made by setting the magnetization reversal length on the outermost peripheral side of the disk, which was about 0.9 microns in the conventional configuration, to about 0.5 micron. Can be improved by 1.8 times.

  Furthermore, in the configuration according to the present embodiment, a large number of periodic signals can be recorded in the servo track area of the same size by reducing the magnetization reversal length on the outer peripheral side, so the number of pulses to be averaged can be reduced. By increasing the number, it is possible to improve the signal S / N and perform more accurate phase detection.

  Compared with the conventional configuration shown in FIG. 16, a 1.8-cycle tracking servo is achieved by setting the magnetization reversal length on the outermost periphery side of the disk to about 0.5 microns, which was about 0.9 microns in the conventional configuration. Signals can be recorded, and the tracking accuracy on the outermost peripheral side of the disk can be improved by about 1.3 times the square root.

  As described above, the configuration according to the present embodiment shown in FIG. 13 can achieve excellent tracking accuracy uniformly and uniformly regardless of the disk radial position. Compared to the conventional configuration shown in FIG. 16, the tracking accuracy can be improved by 2.3 times or more on the outermost side of the disk due to the synergistic effect of the factors related to the phase / distance conversion factor and the signal S / N. It is.

  Although FIG. 13 illustrates the case where the information signal recording area 1b is composed of three segments, the present invention is not limited to this, and the information recording area 1b is divided into two or more segments. Then, the effect as described above can be obtained.

  With the above configuration, the magnetic disk on which information signals such as the reproduction synchronization signal 7, the servo address mark 8, the address information signal 9, and the tracking servo signals 10a and 10b are recorded is mounted on the hard disk drive. In the hard disk drive, the tracking servo signal magnetically recorded by the above configuration may be used as it is as a tracking servo signal when recording / reproducing user data.

  Further, by using the magnetic head mounted on the hard disk drive while referring to the tracking servo signal magnetically transferred and recorded as the first tracking servo signal by the same method as the configuration described in Patent Document 3. The second tracking servo signal may be self-servo recorded and used as a tracking servo signal when recording / reproducing user data. In any case, excellent uniform and uniform tracking accuracy can be realized regardless of the disk radial position.

  By the way, when an information signal magnetically transferred and recorded by the above configuration is reproduced by a magnetic head, there may be a case where the information signal cannot be reproduced properly at the boundary between segments adjacent in the radial direction of the magnetic disk. For example, with respect to the tracking servo signal using the phase detection pattern, the phase continuously changes with the radial displacement of the magnetic disk. However, a continuous phase change accompanying a radial displacement is not detected at a radial position that is a boundary between adjacent segments, and a discontinuous point is generated, and a case where the tracking servo signal cannot be properly reproduced may occur.

  In this case, the phase is detected at the radial positions on both sides of the segment boundary, which is a discontinuity point, that is, it is detected at the radially outermost radial position of the magnetic disk inner peripheral segment among the segments adjacent in the radial direction of the magnetic disk. And the phase detected at the innermost radial position of the segment on the outer peripheral side of the magnetic disk, it is possible to estimate the phase at the discontinuous point.

  In addition to the case of using the phase detection pattern, it is generally possible to maintain the position detection accuracy by the tracking servo signal within the allowable range even at the discontinuous point by the method as described above. Preferably, in the hard disk drive, it is possible to adopt a configuration in which the pattern center of the information signal recorded by magnetic transfer is decentered by an allowable amount with respect to the rotation center of the spindle, that is, the rotation center of the magnetic disk. According to this configuration, the discontinuous points where the signal is not properly reproduced as described above can be suppressed to two places per one circumference of the disk at the radial position near the segment boundary.

  That is, when the pattern center of the information signal and the rotation center of the magnetic disk are completely coincident with each other, the tracking servo signal is not properly reproduced over the entire circumference of the disk at the radial position serving as the boundary between the segments. However, by intentionally decentering the pattern center of the information signal with respect to the rotation center of the magnetic disk, the magnetic head does not actually reproduce the signal properly across the segment boundary at the radial position near the segment boundary. The area can be limited to a limited area of two places per disk. If there are only two discontinuous points where the signal is not properly reproduced per round of the disk, it is possible to interpolate using the tracking servo signal appropriately reproduced at the front and back of the disc, resulting in higher position detection accuracy. Can continue tracking.

  The configuration in which the pattern center of the information signal magnetically transferred and recorded is decentered with respect to the center of rotation of the magnetic disk is, for example, the center of the information signal pattern configured concentrically in the process of magnetic transfer recording. The information signal pattern is obtained by magnetic transfer recording with the geometric center of the magnetic disk being decentered. It can also be realized by mounting the magnetic disk so that the geometric center of the magnetic disk is eccentric from the rotation center of the spindle, that is, the rotation center of the magnetic disk, in the process of mounting the magnetic disk recorded with magnetic transfer on the hard disk drive. .

(Embodiment 2)
The basic configuration of the second embodiment is the same as that of the first embodiment in the method of magnetic transfer recording information signals to the magnetic disk. For this reason, the configuration of the master information carrier as shown in FIGS. 4 to 6 is the same as that of the first embodiment.

  FIG. 14 shows the relationship between the disk radius and the shortest magnetization reversal length of the information signal in the second embodiment. The configuration in FIG. 14 is also a pattern that is magnetically transferred and recorded on a 2.5 inch diameter hard disk, as in FIG. 13 in the first embodiment. The information signal in the present embodiment is also composed of a plurality of segments as in the configuration of the first embodiment. In each segment, the shortest magnetization reversal length increases the radial distance from the center of the magnetic disk. It is configured to increase as the time elapses.

  In the configuration of FIG. 14, the information signal recording area 1b is composed of four segments: a first segment 17a, a second segment 17b, a third segment 17c, and a fourth segment 17d. Is configured such that the magnetization reversal length increases as the radial distance from the center of the magnetic disk increases.

  In other words, when the magnetic disk rotates at a constant rotational speed, the peripheral speed is faster on the outer periphery side of the disk, so the magnetization reversal length is proportional to the radius in each segment, and approximately the same reproduction pulse interval on the time axis. Configured to get. Further, in the second segment 17b to the fourth segment 17d, the magnetization reversal length on the innermost disk side of each segment is configured to have the same value. In other words, the magnetization reversal length on the innermost disk side of the segment adjacent to the outer disk side of the segment is smaller than the magnetization reversal length on the outermost disk side of the segment.

  The configuration of FIG. 14 differs from the configuration of FIG. 13 in that the first segment 17a remains in the range up to the innermost position of the user data area in the configuration of FIG. In other words, the configuration of FIG. 14 includes a dedicated segment separately from the segment in the user data area between the inner peripheral side crash stop position and the user data area innermost peripheral position.

  In the hard disk drive, it is necessary to perform position control by applying a servo to the magnetic head even while the magnetic head moves from the inner peripheral crash stop to the user data area. Therefore, the tracking servo signal needs to be recorded even in the radial region from the inner peripheral side crash stop to the innermost peripheral position of the user data region.

  On the other hand, since the user data is not recorded / reproduced in the radius region from the inner periphery side crash stop to the innermost peripheral position of the user data region, it is not necessary to perform the position control as strictly as the user data region. In other words, it is not necessary to control the tracking of the user data of the adjacent track with such a strict accuracy as not to erase a little. For this reason, the accuracy of the position control until it goes to the user data area where the strict tracking control is performed can be reduced to such an extent that the servo is roughly applied to the extent that the magnetic head does not run away.

  From this point of view, as shown in FIG. 13 in the first embodiment and FIG. 16 in the conventional example, magnetization with excellent tracking accuracy in the radial region from the inner peripheral side crash stop to the innermost peripheral position of the user data region. It can be said that it is not always necessary to use a signal having a small inversion length.

  The configuration shown in FIG. 14 is a configuration found from the viewpoint that a signal having a small magnetization reversal length and excellent tracking accuracy is preferably used in the user data area as much as possible. That is, in the configuration of FIG. 14, the radius region from the inner peripheral side crash stop to the innermost peripheral position of the user data region is covered with the first segment 17a configured with a signal having a relatively large magnetization reversal length that is relatively inferior in tracking accuracy. Has been. As a result, a large number of signals having a relatively small magnetization inversion length with relatively good tracking accuracy can be used in the user data region, so that the tracking accuracy in the user data region can be relatively improved.

  FIG. 15 shows another configuration example of the relationship between the disk radius and the shortest magnetization reversal length of the information signal in the second embodiment. The configuration of FIG. 15 is recorded so that the first segment 17a on the innermost circumference side of the magnetic disk substantially covers the radial area from the inner circumference side crash stop position to the user data area innermost circumference position. This is the same as the configuration of FIG. However, this region also differs from the configuration of FIG. 14 in that a signal having a small magnetization reversal length with excellent tracking accuracy is used.

  Also in the configuration of FIG. 15, it is possible to obtain the effect of the present embodiment that the tracking accuracy in the user data area can be relatively improved. However, in the configuration of FIG. 15, as in the configurations of FIGS. 13 and 14, the magnetization reversal length of the first segment 17a on the outermost disk side is the same as the magnetization reversal length of the second segment 17b on the innermost disk side. Or an integral multiple of half of the magnetization reversal length on the innermost disk side of the second segment 17b.

  Therefore, the configuration of FIG. 14 is more advantageous in that the setting of the clock frequency in the hard disk drive is simplified. On the other hand, the configuration of FIG. 15 can provide a sufficient margin in tracking accuracy in the radial region from the inner peripheral side crash stop position to the user data region innermost peripheral position, compared to the configuration of FIG. Therefore, whether to select the configuration of FIG. 14 or the configuration of FIG. 15 may be appropriately determined according to the required performance, quality, and the like.

  14 and 15 exemplify the case where the information signal recording area 1b is composed of four segments. However, the present invention is not limited to this, and the information recording area 1b includes two or more segments. If it is divided, the effect of the present embodiment can be obtained.

  That is, as an example of the simplest configuration, two segments are provided, and the first segment substantially covers the radial area from the inner peripheral side crash stop position of the magnetic disk to the innermost peripheral position of the user data area. A configuration in which the segment covers the remaining information recording area 1b including the user data area can be mentioned. Even in such a configuration, the effect of the present embodiment can be obtained.

  With the above configuration, the magnetic disk on which information signals such as the reproduction synchronization signal 7, the servo address mark 8, the address information signal 9, and the tracking servo signals 10a and 10b are recorded is mounted on the hard disk drive.

  Similarly to the configuration of the first embodiment, the tracking servo signal recorded by magnetic transfer may be used as it is as a tracking servo signal when recording / reproducing user data. Further, by using the magnetic head mounted on the hard disk drive while referring to the tracking servo signal magnetically transferred and recorded as the first tracking servo signal by the same method as the configuration described in Patent Document 3. The second tracking servo signal may be self-servo recorded and used as a tracking servo signal when recording / reproducing user data.

  As in the first embodiment, in order to more reliably reproduce the information signal in the signal discontinuous region at the boundary between the segments, in the hard disk drive, the pattern center of the information signal recorded magnetically is recorded. The center of rotation of the spindle, that is, the center of rotation of the magnetic disk may be offset by an allowable amount. The method for realizing this configuration is as described in the first embodiment.

  According to the present invention, the uniformity of the magnetization reversal length of the signal can be improved over the entire surface of the magnetic disk, which is useful for increasing the density and reducing the capacity of the hard disk drive. Further, the present invention is applicable not only to hard disk drives but also to other magnetic disk drive applications such as large capacity flexible disk drives.

1 is a cross-sectional view showing an outline of a recording apparatus for performing magnetic transfer recording of an information signal in Embodiment 1 of the present invention. FIG. 3 is a perspective view showing a configuration example of a magnetizing head according to the first embodiment of the present invention. The top view which shows the structural example of the one main surface facing the master information carrier of the magnetization head in Embodiment 1 of this invention. The top view which shows the structural example of the master information carrier in Embodiment 1 of this invention. The top view which showed typically the structural example of the arrangement pattern of the information signal formed in the master information carrier in Embodiment 1 of this invention. Sectional drawing which shows the structural example of the master information carrier in Embodiment 1 of this invention. The perspective view which shows the state which is carrying out the direct-current erasing of the hard disk in Embodiment 1 of this invention. The perspective view which shows typically the state of the hard disk by which direct-current erasure | elimination was carried out by the process shown in FIG. 1 is a perspective view showing a state where an information signal is magnetically transferred and recorded on a hard disk in Embodiment 1 of the present invention. FIG. The perspective view which shows typically the state of the hard disk by which the information signal was recorded by the process shown in FIG. Sectional drawing for demonstrating typically the magnetization state at the time of carrying out magnetic transfer recording of the information signal to a hard disk by the process shown in FIG. Sectional drawing for demonstrating typically the change of the magnetization state at the time of carrying out magnetic transfer recording of the information signal to a hard disk by Embodiment 1 of this invention. The figure which shows an example of the relationship between the disc radius and the shortest magnetization reversal length of an information signal in Embodiment 1 of this invention. The figure which shows an example of the relationship between the disk radius and the shortest magnetization reversal length of an information signal in Embodiment 2 of this invention. The figure which shows another example of the relationship between the disc radius and the shortest magnetization reversal length of an information signal in Embodiment 2 of this invention. The figure which shows an example of the relationship between the disc radius in the past, and the shortest magnetization reversal length of an information signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hard disk 1a Center hole 1b Information signal recording area 1c Magnetic recording layer 2 Master information carrier 2a Signal area 2b Magnetic part 7 Playback synchronous signal 8 Servo address mark 9 Address information signal 10a, 10b Tracking servo signal 11 Base 11a Base recess 11b Main surface of substrate 12 Ferromagnetic thin film 17a First segment 17b Second segment 17c Third segment 17d Fourth segment

Claims (11)

A shape pattern of a ferromagnetic material corresponding to an information signal is formed on the surface of the substrate as a master information carrier, and the master information carrier is brought into contact with the surface of the magnetic disk to apply an external magnetic field, thereby corresponding to the shape pattern. A method of manufacturing a magnetic disk comprising a step of recording an information signal on the magnetic disk as magnetization information,
The shape pattern is formed by forming a plurality of segments adjacent to each other in the radial direction of the magnetic disk by recording the magnetization information so that the shortest magnetization reversal length increases as the radial distance from the center of the magnetic disk increases. Pattern,
When the two segments adjacent to each other in the radial direction of the magnetic disk are viewed as the plurality of segments, the shortest magnetization reversal length on the inner peripheral side of the magnetic disk among the magnetization reversal lengths on the outer peripheral side of the magnetic disk. Is smaller than the shortest magnetization reversal length on the outer peripheral side of the magnetic disk, among the magnetization reversal lengths of the segments on the inner peripheral side of the magnetic disk.   The method of manufacturing a magnetic disk according to claim 1, wherein the information signal includes a tracking servo signal.   3. The magnetic field according to claim 2, wherein the tracking servo signal includes a phase detection signal pattern capable of specifying a radial position of the magnetic disk by detecting a phase change of a reproduction signal accompanying a radial displacement of the magnetic disk. Disc manufacturing method.   The tracking servo signal is a signal pattern configured in a concentric circle shape, and the signal pattern is recorded by decentering the signal pattern center and the center of the magnetic disk. A method of manufacturing a magnetic disk.   Among the plurality of segments, an innermost segment in the radial direction of the magnetic disk is formed between an inner peripheral crash stop position of the magnetic disk and a user data area innermost position, and the user data The method of manufacturing a magnetic disk according to claim 1, wherein the magnetic disk is formed separately from the segments in the region. A magnetic recording / reproducing apparatus equipped with a magnetic disk on which information signals are recorded in advance,
The magnetic disk has a plurality of segments adjacent to each other in the radial direction of the magnetic disk, wherein the shortest magnetization reversal length increases as the radial distance from the center of the magnetic disk increases.
When the two segments adjacent to each other in the radial direction of the magnetic disk are viewed as the plurality of segments, the shortest magnetization reversal length on the inner peripheral side of the magnetic disk among the magnetization reversal lengths on the outer peripheral side of the magnetic disk. Is smaller than the shortest magnetization reversal length on the outer peripheral side of the magnetic disk among the magnetization reversal lengths of the inner peripheral segment of the magnetic disk.   The magnetic recording / reproducing apparatus according to claim 6, wherein the information signal includes a tracking servo signal.   The magnetic signal according to claim 7, wherein the tracking servo signal includes a phase detection signal pattern capable of specifying a radial position of the magnetic disk by detecting a phase change of a reproduction signal accompanying a radial displacement of the magnetic disk. Recording / playback device.   9. The magnetic recording / reproducing apparatus according to claim 7, wherein the tracking servo signal is a signal pattern configured in concentric circles, and a center of the signal pattern and a center of the magnetic disk are decentered.   Among the plurality of segments, an innermost segment in the radial direction of the magnetic disk is formed between an inner peripheral crash stop position of the magnetic disk and a user data area innermost position, and the user data The magnetic recording / reproducing apparatus according to claim 9, wherein the magnetic recording / reproducing apparatus is formed separately from the segments in the region. A method of manufacturing a magnetic recording / reproducing apparatus equipped with a magnetic disk in which an information signal is recorded in advance,
By forming a shape pattern of a ferromagnetic material corresponding to the first tracking servo signal on the surface of the substrate as a master information carrier, by applying an external magnetic field by bringing the master information carrier into contact with the surface of the magnetic disk, Recording the first tracking servo signal corresponding to the shape pattern on the magnetic disk as magnetization information,
The shape pattern is formed by forming a plurality of segments adjacent to each other in the radial direction of the magnetic disk by recording the magnetization information so that the shortest magnetization reversal length increases as the radial distance from the center of the magnetic disk increases. When the two segments adjacent to each other in the radial direction of the magnetic disk are seen from the magnetization reversal lengths of the segments on the outer peripheral side of the magnetic disk, the plurality of segments are located on the innermost side of the magnetic disk. The shortest magnetization reversal length is smaller than the shortest magnetization reversal length on the outer peripheral side of the magnetic disk, among the magnetization reversal lengths of the inner peripheral segment of the magnetic disk,
Further, after the magnetic disk is mounted on the magnetic recording / reproducing apparatus, the first magnetic head is positioned by positioning the magnetic head mounted on the magnetic recording / reproducing apparatus with reference to the first tracking servo signal. A method of manufacturing a magnetic recording / reproducing apparatus, comprising: a step of recording a second tracking servo signal different from the tracking servo signal.

Images