JP2002367164A - Method of manufacturing magnetic recording medium and head for magnetization for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of regenerative signal quality which occurs depending upon various conditions in preformat recording or the admission of the phenomenon of an unknown cause that the quality described above changes unstably according to the places on a magnetic recording medium in a preformat recording technique using a master information carrier which is a novel technique relating to the preformat recording of the magnetic recording medium. SOLUTION: The method of manufacturing the magnetic recording medium by superposing the master information carrier 2 having the patterns of ferromagnetic thin films 11 formed to the shapes corresponding to prescribed information signals onto the disk-like magnetic recording medium 1 and magnetizing the patterns corresponding to the information signals of the master information carrier 2 by a head 6 for magnetization having a gap 6d formed by disposing a first magnetic core half body 6b and a second magnetic core half body 6c opposite to each other, thereby magnetically transferring the patterns corresponding to the information signals of the master information carrier 2 to the magnetic recording medium 1, in which the gap length of the head 6 for magnetization is so set as to be greater than in the position corresponding to the inner peripheral side in the position corresponding to the outer peripheral side of the magnetic recording medium 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a magnetic recording medium, and more particularly to a technique for recording a predetermined information signal on a magnetic recording medium used in a magnetic recording / reproducing apparatus. The present invention also relates to a magnetizing head used in a method for manufacturing a magnetic recording medium. Further, the present invention relates to a hard disk drive and a magnetic recording / reproducing device.

[0002]

2. Description of the Related Art In recent years, magnetic recording / reproducing apparatuses have tended to have high recording densities in order to realize a small size and a large capacity.
In the field of hard disk drives, which are typical magnetic storage devices, the areal recording density is already 10 Gbit / in.
² (15.5 Mbit / mm ² ) has been commercialized, and at present, 20 Gbit / in ² (31.0 Mbit / mm ² )
A rapid technical progress has been recognized such that practical application of areal recording density exceeding Mbit / mm ² ) is discussed.

[0003] As a technical background enabling such a high recording density, the improvement of the medium performance, the head-disk interface performance, and the improvement of the linear recording density due to the emergence of a new signal processing system such as a partial response are also significant. Is a factor. However, in recent years, the trend of increase in track density greatly exceeds the trend of increase in linear recording density, which is a major factor for improving the areal recording density. This is based on the contribution of the practical use of a magnetoresistive element type head which is much more excellent in reproduction output performance than a conventional induction type magnetic head. At present, the practical use of a magnetoresistive element type head makes it possible to reproduce a track width signal of only a few μm or less with good S / N. On the other hand, it is expected that the track pitch will reach the submicron region in the near future with further improvement in head performance in the future.

In order for the head to accurately scan such a narrow track and reproduce a signal with good S / N, the tracking servo technique of the head plays an important role. With respect to such tracking servo technology, in the current hard disk drive, a tracking servo signal, an address information signal, a reproduction clock signal, and the like are recorded at a constant angular interval in one round of the disk, that is, within 360 degrees in angle. (Hereinafter referred to as
Preformat). By reproducing these signals at regular intervals, the magnetic head can accurately scan the track while confirming and correcting the position of the head.

The above-described tracking servo signal, address information signal, reproduced clock signal, and the like serve as reference signals for the head to accurately scan the track. Required. In a current hard disk drive, after a disk is incorporated in the drive, preformat recording is performed by a magnetic head whose position is strictly controlled using a dedicated servo recording device.

Conventionally, there have been the following problems in preformat recording of a servo signal, an address information signal, and a reproduced clock signal by a magnetic head using the above-described dedicated servo recording device.

First, recording with a magnetic head is basically line recording based on the relative movement between the head and the medium. Therefore, in the above-described method of performing recording while strictly controlling the position of the magnetic head using a dedicated servo recording device, preformat recording requires a lot of time, and the dedicated servo recording device is considerably expensive. This results in a very high cost.

Secondly, because of the spread of the recording magnetic field due to the spacing between the head and the medium and the pole shape of the recording head,
There is a problem that the transition of the magnetization at the end of the track on which the preformat recording is performed lacks sharpness. The current tracking servo technology detects the position of the head based on the amount of change in the reproduction output when the head scans off the track. Therefore, the signal track recorded in the preformat is not only excellent in the S / N when the head accurately scans the track, such as when reproducing the data information signal recorded in the servo area, but also in the head. Is required to have a steep reproduction output change amount when scanning off the track, that is, off-track characteristics. The above problem is contrary to this requirement, and makes it difficult to realize an accurate tracking servo technique in the future submicron track recording.

Therefore, the following method has been proposed as a means for solving the above-mentioned problem of the conventional preformat recording using a magnetic head.

[0010] For example, Japanese Patent Application Laid-Open No. 10-45544 discloses that a magnetic portion made of a ferromagnetic material is formed on a surface of a base in a pattern shape corresponding to an information signal to form a master information carrier. Is brought into contact with the surface of a sheet-shaped or disk-shaped magnetic recording medium on which a ferromagnetic thin film or a ferromagnetic powder coating layer is formed, and by applying a predetermined magnetic field, a pattern shape corresponding to the information signal formed on the master information carrier is formed. A method of recording a magnetization pattern of a magnetic recording medium on a magnetic recording medium is disclosed.

In the configuration disclosed in Japanese Patent Application Laid-Open No. 10-45544, a recording magnetic field generated from a ferromagnetic thin film on the surface of a master information carrier magnetized in one direction is used.
A magnetic pattern corresponding to the ferromagnetic thin film pattern of the master information carrier is transferred and recorded (magnetically transferred) on the magnetic recording medium. That is, a ferromagnetic thin film pattern corresponding to a tracking servo signal, an address information signal, a reproduction clock signal, etc. is formed on the surface of the master information carrier by photolithography technology or the like. Format recording can be performed.

The recording by the conventional magnetic head is basically a dynamic linear recording based on the relative movement between the head and the medium. On the other hand, the feature of the above configuration is that the recording is accompanied by the relative movement between the master information carrier and the medium. There is no static surface record. Due to such features, Japanese Patent Application Laid-Open No. 10-45544
The technique disclosed in Japanese Patent Application Laid-Open Publication No. HEI 9-16095 can exert the following extremely effective effects on the above-described problem in preformat recording.

First, because of the surface recording, the time required for preformat recording is much shorter than that of a conventional recording method using a magnetic head. Further, an expensive servo recording device for performing recording while strictly controlling the position of the magnetic head is not required. Therefore, the productivity in preformat recording can be greatly improved, and the production cost can be reduced.

Second, since static recording does not involve relative movement between the master information carrier and the magnetic recording medium, the surface between the master information carrier and the magnetic recording medium is brought into close contact with each other so that a gap between the two during recording can be obtained. Pacing can be minimized. Further, unlike the recording by the magnetic head, the recording magnetic field does not spread due to the pole shape of the recording head, so that the magnetization transition at the end of the track on which the preformat recording is performed is smaller than the recording by the conventional magnetic head. It has excellent steepness and enables more accurate tracking.

[0015]

In recording an information signal using such a magnetic transfer technique, an array pattern corresponding to the information signal provided on a master information carrier is once recorded on a magnetic recording medium as a magnetization pattern. Therefore, it is important that the magnetic transfer of the pattern corresponding to the information signal on the master information carrier to the magnetic recording medium be performed uniformly and stably over the entire surface of the magnetic recording medium.

However, depending on various conditions at the time of preformat recording, the quality of the reproduced signal may be degraded, or may be unstablely changed depending on the position on the magnetic recording medium. Deterioration of the reproduction signal quality leads to a defect in servo tracking of the magnetic recording / reproducing apparatus.

In some cases, the deterioration phenomenon of the signal quality can be prevented to some extent by experimentally optimizing various conditions at the time of preformat recording.

However, when mass-producing a magnetic recording / reproducing apparatus by using the preformat recording technique, a certain wide range of allowable range under appropriate preformat recording conditions is required from the viewpoints of product quality assurance and production yield improvement. is necessary.

Under the appropriate recording conditions derived by a trial and error experimental method in the current preformat recording technology, the allowable range allowed from the viewpoint of signal quality is very narrow, and the quality assurance of products during mass production is However, it is hard to say that it is sufficiently practical from the viewpoint of improving the production yield.

The present inventors have repeatedly conducted various experiments and studies on this problem, and as a result, have found that the above signal quality degradation phenomenon is caused by the following effects. The case where the magnetic recording medium is a disk-shaped magnetic recording medium will be described.

The length of each ferromagnetic thin film pattern on the master information carrier in the circumferential direction of the disk is determined by a predetermined pulse interval on the time axis in a reproduction signal when reproducing the transferred and recorded information using a magnetic head. It is designed to get However, since the rotational speed of the disk-shaped magnetic recording medium on which the transfer is recorded is constant, the peripheral speed at one point on the disk is higher at the outer periphery of the disk than at the inner periphery of the disk. Therefore, in order to obtain a constant pulse interval from the inner circumference to the outer circumference in a signal waveform when a certain transferred and recorded signal is reproduced by the magnetic head, the length of the ferromagnetic thin film pattern in the circumferential direction of the disk is set closer to the outer circumference. It needs to be bigger.

That is, in order to obtain a constant pulse interval for a certain kind of signal, the length of the individual ferromagnetic thin films on the master information carrier and the interval between the individual ferromagnetic thin films are set closer to the outer periphery than to the inner periphery. Is getting bigger.

On the other hand, since a ferromagnetic thin film is deposited at a constant film forming rate by using a sputtering method or the like, its film thickness is generally constant regardless of the inner circumference and the outer circumference.
That is, the cross section of each ferromagnetic thin film has an elongated shape in which the ratio of length to film thickness (= length / film thickness) is smaller toward the inner periphery and larger in the outer periphery.

In such ferromagnetic thin film patterns having different cross-sectional shapes, when a magnetic field for magnetic transfer is applied by a magnetizing head, the difference in magnetic anisotropy accompanying the shape causes the magnetization process and The characteristics of transfer recording to a magnetic recording medium differ. That is, when the magnetic characteristics of the magnetic recording medium are uniform over the entire surface of the disk, the value of the applied magnetic field that obtains the optimum value in the leakage flux contributing to the magnetization reversal and obtains the optimum value in the transfer recording characteristics is Will differ depending on the radius position. For this reason, when transfer recording is performed in an applied magnetic field capable of obtaining good signal quality on the inner peripheral side, the signal quality on the outer peripheral side is below the allowable limit, or conversely, good signal quality is obtained on the outer peripheral side. When transfer recording is performed with an applied magnetic field that can be applied, a phenomenon occurs in which the signal quality on the inner peripheral side deteriorates below an allowable limit.

The present invention has been made in view of the above-mentioned circumstances, and a master information carrier for a disk-shaped magnetic recording medium, particularly a magnetic recording medium such as a fixed hard disk medium, a removable hard disk medium, and a large-capacity flexible medium. It is an object of the present invention to enable the magnetic transfer of a pattern corresponding to the above information signal to be performed uniformly and stably over the entire surface of a magnetic recording medium.

[0026]

The method of manufacturing a magnetic recording medium according to the present invention is based on the following premise. A master information carrier on which a ferromagnetic thin film pattern corresponding to an information signal is formed is used. The master information carrier is superimposed on a disk-shaped magnetic recording medium, and the information on the master information carrier is provided by a magnetizing head having a first magnetic core half and a second magnetic core half facing each other with a gap. The magnetic part of the pattern corresponding to the signal is magnetized. As a result, the leakage magnetic flux from the magnetic portion of the pattern acts on the magnetic recording medium superimposed on the master information carrier, and the pattern corresponding to the information signal on the master information carrier is magnetically transferred to the magnetic recording medium.

The present invention solves the above problem by taking the following means in such a method for manufacturing a magnetic recording medium. That is, a magnetic field for magnetic transfer is applied from the magnetizing head to the magnetic portion of the pattern corresponding to the information signal on the master information carrier by the leakage magnetic flux of the magnetizing head. In order to apply the applied magnetic field in a state in which the applied magnetic field becomes smaller toward the outer periphery of the recording medium, a magnetizing head having a larger gap length toward the outer periphery of the magnetic recording medium is used as the magnetizing head.

The operation of the present invention is as follows. The present inventors have clarified the magnetic mechanism for making the optimum magnetic field value different at the disk radial position as follows.

In other words, the outer peripheral pattern having a large ratio of length to film thickness (= length / film thickness) has a small demagnetizing field in the direction of application of the applied magnetic field by the magnetizing head, and is therefore saturated at a smaller magnetic field value. Easy to reach. Conversely, in the inner circumferential pattern having a small ratio of length to film thickness, the demagnetizing field in the direction of application of the applied magnetic field by the magnetizing head is larger than that in the outer circumferential direction. Therefore, in order to obtain the same value of the leakage flux contributing to the magnetization reversal in the region corresponding to between the ferromagnetic thin films on the disk-shaped magnetic recording medium, it is necessary to apply a larger applied magnetic field at the inner periphery than at the outer periphery. Become. As described above, when transfer recording is performed using an applied magnetic field that can obtain an optimum leakage magnetic flux on the outer periphery and obtain an optimum signal quality, a sufficient magnetization can be obtained in a region corresponding to between the ferromagnetic thin films on the inner periphery. Inversion is not obtained and signal quality is degraded. Conversely, when transfer recording is performed using an applied magnetic field that can obtain an optimum leakage magnetic flux on the inner circumference and obtain an optimum signal quality, the outer peripheral side ferromagnetic thin film reaches saturation. That is, leakage magnetic flux is generated even on the ferromagnetic thin film by application of the applied magnetic field, and unnecessary magnetization reversal of the magnetic recording medium is caused, thereby deteriorating the signal quality.

As described above, the optimum value of the magnetic field to be applied to the magnetic recording medium due to the magnetic flux leaking from the magnetizing head is:
Based on the finding that the inner circumference is larger than the outer circumference, in the present invention, the magnetic field applied to the master information carrier by the magnetic flux leaking from the magnetizing head has a gap closer to the outer circumference of the magnetic recording medium. By using the magnetizing head having a large length, the magnetic field applied to the outer peripheral side of the magnetic recording medium is made smaller than the applied magnetic field to the inner peripheral side. As a result, a sufficient magnetization reversal is obtained on the inner peripheral side, and the generation of a leakage magnetic flux of the opposite polarity on the ferromagnetic thin film is suppressed to an allowable range or less on the outer peripheral side. Signal quality can be obtained.

According to the present invention having this configuration, the magnetic transfer of the pattern corresponding to the information signal on the master information carrier to the magnetic recording medium can be performed uniformly and stably over the entire surface of the magnetic recording medium.

The present invention relates to a magnetizing head for use in the above-mentioned method for manufacturing a magnetic recording medium, wherein the magnetizing head has a gap formed in a monotonously and continuously large gap length toward the outer peripheral side of the magnetic recording medium. Use a head.

According to the present invention for the magnetizing head,
In performing the above magnetic recording medium manufacturing method, the magnetic transfer of the pattern corresponding to the information signal on the master information carrier to the magnetic recording medium can be performed uniformly and stably over the entire surface of the magnetic recording medium. It can be achieved easily and inexpensively.

Further, according to the present invention, it is possible to realize a hard disk drive having a built-in magnetic recording medium that has been preformat-recorded by using the above-described method for manufacturing a magnetic recording medium.

Further, according to the present invention, a magnetic recording / reproducing apparatus incorporating a magnetic recording medium in which a magnetization pattern of a predetermined information signal is magnetically transferred to a magnetic film in advance by using the above-described method for manufacturing a magnetic recording medium is realized. be able to.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be generally described.

According to the first aspect of the present invention, the first magnetic core half and the second magnetic core half are placed in a state where the master information carrier is overlaid on the disk-shaped magnetic recording medium. By magnetizing the magnetic part of the master information carrier by a magnetizing head having a gap in opposition, a pattern corresponding to an information signal on the master information carrier is formed on the magnetic recording medium with a leakage magnetic flux from the magnetic part. A method of manufacturing a magnetic recording medium for magnetic transfer, wherein the master information for the magnetic transfer is formed by using a magnetizing head having a gap length larger on the outer peripheral side of the magnetic recording medium as the magnetizing head. It is characterized in that the carrier is magnetized.

The operation according to the first aspect of the present invention is substantially the same as that described in the above section [Means for Solving the Problems]. That is, the magnetic transfer of the pattern corresponding to the information signal on the master information carrier to the magnetic recording medium can be performed uniformly and stably over the entire surface of the magnetic recording medium.

According to a second aspect of the present invention, in the method of the first aspect, at least one of the first magnetic core half and the second magnetic core half is used as the magnetizing head. One uses a magnetizing head composed of permanent magnets. This is for forming an annular magnetic path for magnetization.

According to a third aspect of the present invention, in the method for manufacturing a magnetic recording medium according to the first aspect, both the first magnetic core half and the second magnetic core half are used as the magnetizing head. A magnetizing head joined with a permanent magnet interposed therebetween is used.

The operation of the third invention is as follows. By interposing a permanent magnet between the first magnetic core half and the second magnetic core half on the opposite side of the gap, the first magnetic core half and the second magnetic core half are separated from each other. It is possible to uniformly magnetize the magnetic circuit formed by these components in the direction along the annular magnetic path. As the permanent magnet to be interposed, a block-shaped rectangular parallelepiped magnet can be used. Compared with a magnetizing head using a yoke-shaped permanent magnet, a magnetizing head using a rectangular parallelepiped permanent magnet is less expensive, and magnetically transfers a pattern corresponding to an information signal on a master information carrier to a magnetic recording medium. Can be implemented at lower cost.

According to a fourth aspect of the present invention, there is provided the magnetic recording medium manufacturing method according to the first aspect, wherein the magnetizing head is one of the first magnetic core half and the second magnetic core half. At least one uses a magnetizing head having a DC excitation winding.

The operation of the fourth invention is as follows. It is necessary to uniformly magnetize the first and second magnetic core halves having a yoke shape in a direction along the annular magnetic path of the magnetic circuit formed by the first and second magnetic core halves. It may be difficult to magnetize uniformly in the direction along. When the core is excited by the DC excitation winding, the first magnetic core half and the second magnetic core half are uniformly magnetized in a direction along the annular magnetic path of the magnetic circuit formed by them. To be sure.

According to a fifth aspect of the present invention, in the method for manufacturing a magnetic recording medium according to the first to fourth aspects, prior to the magnetic transfer step, a DC erasing magnetic field is applied to the magnetic recording medium in a predetermined direction. In the step of magnetic transfer in a state in which the master information carrier is superimposed on the magnetized magnetic recording medium, the direct current is applied to the magnetic portion of the master information carrier using the magnetizing head. A pattern corresponding to the information signal on the master information carrier is magnetically transferred to the magnetic recording medium by applying a magnetic field having a polarity opposite to that of the erasing magnetic field.

The operation of the fifth invention is as follows. The magnetic recording medium is subjected to DC erasing in advance and magnetized uniformly, and a magnetic field with the opposite polarity is applied to the magnetic recording medium in the uniformly magnetized state and a pattern corresponding to the information signal on the master information carrier is applied. Is performed, the steepness of the magnetization transition at the boundary between the information signal region and the non-information signal region becomes high.

The method for manufacturing a magnetic recording medium according to a sixth aspect of the present invention is the method according to the fifth aspect, wherein the first magnetic core half and the second magnetic core are used as a magnetizing head for applying a DC erasing magnetic field to the magnetic recording medium. An annular magnetic path having a gap is formed by facing the magnetic core half, and a magnetizing head having a substantially constant gap length in the radial direction of the magnetic recording medium is used. .

The operation of the sixth invention is as follows. As for the magnetic field applied from the magnetizing head to the master information carrier when the pattern corresponding to the information signal on the master information carrier is magnetically transferred to the magnetic recording medium, the applied magnetic field on the outer peripheral side is changed to the applied magnetic field on the inner peripheral side as described above. Although it is better to make it smaller, it is not preferable to make the DC erasing magnetic field different in the radial direction for the initial magnetization (DC erasing) of the magnetic recording medium prior to the magnetic transfer. For the initial magnetization, a constant DC erasing magnetic field in the radial direction has a favorable effect in the subsequent magnetic transfer of the pattern corresponding to the information signal on the master information carrier.

The seventh to eleventh aspects of the present invention relate to a magnetizing head used in the above-described method of manufacturing a magnetic recording medium.

In the magnetizing head for manufacturing a magnetic recording medium according to the seventh aspect of the present invention, the gap facing the head main surface facing the master information carrier is monotonously and continuously monotonically and continuously with respect to the outer periphery of the magnetic recording medium in the gap length. It is characterized in that it is formed in a shape that becomes larger as it becomes larger.

The operation of the seventh aspect is as follows. In order to uniformly and stably perform the magnetic transfer of the pattern corresponding to the information signal on the master information carrier to the magnetic recording medium over the entire surface of the magnetic recording medium, the magnetic field applied from the magnetizing head to the master information carrier must be: It is better to make the outer applied magnetic field smaller than the inner applied magnetic field. One of the simplest measures in a magnetizing head to compensate for this is the seventh invention. I have. In other words, the gap facing the master main surface facing the master information carrier has a difference in the radial direction instead of making the gap length uniform as in the related art. Based on the gap length on the inner peripheral side, the gap length is devised so as to gradually increase toward the outer peripheral side. This is described as monotonous and continuous.

The magnetizing head according to the eighth aspect of the present invention comprises a first magnetic core half and a second magnetic core half joined in a gap-formed state, and a head main surface facing the master information carrier. Is formed such that the gap length is monotonously and continuously increased in the gap length toward the outer peripheral side of the magnetic recording medium. This describes that the magnetizing head is composed of a combination of the first magnetic core half and the second magnetic core half.

A ninth aspect of the present invention is the magnetizing head according to the eighth aspect, wherein the first magnetic core half and the second
At least one of the magnetic core halves is made of a permanent magnet.

The operation of the ninth invention is as follows. A first magnetic core half and a second magnetic core half,
It is preferable that the magnets are uniformly magnetized in the direction along the annular magnetic path of the magnetic circuit formed by the magnets. However, the magnetization direction is equalized by forming at least one of the magnetic core halves with a permanent magnet. This is achieved by: In addition, as the permanent magnet, a rare earth magnet mainly containing a material such as Nd—Fe—B or Sm—Co is preferable.

The tenth aspect of the present invention is the magnetizing head according to the eighth aspect, wherein the first magnetic core half and the second magnetic core half have a permanent magnet interposed therebetween. It is what is joined by.

The operation of the tenth aspect is as follows. As the permanent magnet interposed between the first magnetic core half and the second magnetic core half on the opposite side of the gap, a block-shaped rectangular parallelepiped can be used. Compared with a magnetizing head using a yoke-type permanent magnet, a magnetizing head using a rectangular parallelepiped permanent magnet can be realized at lower cost. In addition, as materials constituting the first and second magnetic core halves,
Instead of a permanent magnet material, various types of ferromagnetic materials having soft or semi-hard magnetism can be used.

Note that the ferromagnetic material constituting the first and second magnetic core halves has a sufficiently high saturation magnetic flux density so as not to cause significant magnetic saturation locally due to the magnetic flux supplied from the permanent magnet. Preferably, for example, F
e, an Fe—Co alloy, an Fe—Si soft magnetic alloy material, or the like is preferable.

According to an eleventh aspect of the present invention, in the magnetizing head according to the eighth aspect, at least one of the first magnetic core half and the second magnetic core half is a DC excitation winding. Is provided.

The operation according to the eleventh invention is as follows. It is necessary to uniformly magnetize the first and second magnetic core halves having a yoke shape in a direction along the annular magnetic path of the magnetic circuit formed by the first and second magnetic core halves. It may be difficult to magnetize uniformly in the direction along. On the other hand, if the core is excited by the DC excitation winding, the magnetization direction can be made uniform, and the material constituting the first and second magnetic core halves is not a permanent magnet material. Alternatively, ferromagnetic materials having various types of soft magnetism or semi-hard magnetism can be used. That is, it is not necessary to provide a permanent magnet as a component of the magnetic core, so that the trouble of magnetizing in an appropriate direction can be eliminated and the yoke-shaped magnetic core half can be easily formed.

The twelfth aspect of the present invention relates to a hard disk drive, and is manufactured by the magnetic recording medium manufacturing method according to the first to sixth aspects, and a magnetic pattern of a predetermined information signal is magnetically transferred to a magnetic film in advance. And a built-in magnetic recording medium.

The operation of the twelfth invention is as follows. A high-density recording hard disk that has a sufficiently high reliability as a tracking servo signal, an address information signal, a reproduction clock signal, and other information signals is preformat-recorded, and in particular, a magnetic transition at a track end. Since a hard disk having excellent steepness is provided, tracking servo in submicron track recording can be performed with high accuracy. Further, since such a hard disk can be efficiently produced, a hard disk drive having excellent performance can be provided at relatively low cost.

The thirteenth invention of the present application relates to a magnetic recording / reproducing apparatus, and has a structure in which a magnetic recording medium pre-format-recorded by using the magnetic recording medium manufacturing method of the first to sixth inventions is incorporated. It is characterized by being.

The operation according to the thirteenth aspect is as follows. A high-density recording magnetic recording medium that has a sufficiently high reliability as a tracking servo signal, an address information signal, and a reproduction clock signal, etc., and is preformat-recorded, especially a magnetization at a track end. Since the magnetic recording medium having the excellent transition steepness is provided, the tracking servo in submicron track recording can be performed with high accuracy. And
Since such a magnetic recording medium can be efficiently produced, a magnetic recording / reproducing apparatus having excellent performance can be provided at a relatively low cost.

(Specific Embodiment) Hereinafter, a specific embodiment of a method for manufacturing a magnetic recording medium according to the present invention will be described with reference to the drawings.

(Embodiment 1) A method for manufacturing a magnetic recording medium (a method for recording on a magnetic recording medium) according to Embodiment 1 of the present invention will be described with reference to the drawings.

FIG. 1 shows an outline of a recording apparatus for performing the recording method according to the present embodiment. In FIG. 1, a disk-shaped hard disk 1 as a magnetic recording medium is provided on a surface of a donut disk-shaped non-magnetic substrate having a center hole 1a.
It is formed by forming a ferromagnetic thin film mainly containing Co or the like by a sputtering method.

Reference numeral 2 denotes a disk-shaped master information carrier which is disposed so as to be in contact with the surface of a magnetic film made of a ferromagnetic thin film or the like of the hard disk 1. A signal region 2a made of a ferromagnetic thin film having a fine array pattern corresponding to an information signal to be magnetically transferred to the hard disk 1 is provided on the surface on the side in contact with the hard disk 1 having a shape larger than the diameter of the hard disk 1. .

Reference numeral 3 denotes a disk holder for holding the hard disk 1, and a chuck 3a for positioning and holding the hard disk 1 is provided at the tip of the disk holder 3. Further, a suction hole 3 b communicating with the center hole 1 a of the hard disk 1 and having one end connected to the exhaust duct 4 is provided inside the disk holder 3.

Further, an exhaust device 5 is provided at the end of the exhaust duct 4.
When the exhaust device 5 is started, the space between the hard disk 1 and the master information carrier 2 is brought into a negative pressure state through the exhaust duct 4 and the suction hole 3b of the disk holder 3, and as a result, Then, the master information carrier 2 is sucked in the direction of the hard disk 1 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 the 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 transferring and recording from the master information carrier 2 to the hard disk 1 and corresponds to an information signal formed on the master information carrier 2 by the magnetic field applied from the magnetizing head 6. The ferromagnetic thin film pattern thus magnetized is magnetized, and an information signal is recorded on the hard disk 1 by magnetic flux leakage generated from these (magnetic transfer).

As shown in FIG. 2, for example, the magnetizing head 6 includes a first magnetic core half 6b made of a ferromagnetic material.
And a second magnetic core half 6c made of a ferromagnetic material having a winding 6a and facing each other to form an annular magnetic circuit having a gap 6d, and applying an exciting current to the winding 6a. By doing so, the gap A
As shown by, a leakage magnetic flux from the first magnetic core half 6b toward the second magnetic core half 6c is generated, and the direction of the leakage magnetic flux generated in the gap 6d is changed by changing the direction of the applied current. be able to.

The 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.

As shown in FIG. 3, the magnetizing head 6
The shape of the gap 6d is the same arc shape as the tracking scanning trajectory (rotation trajectory of the head actuator tip) of the recording / reproducing magnetic head on the head main 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 all the tracks in the direction perpendicular to the tracking scanning direction of the recording / reproducing magnetic head. Is done. That is, it is magnetized in the same direction as the head gap length direction of the recording / reproducing magnetic head.

Next, an example of the master information carrier used in the magnetic recording medium manufacturing method of the present invention will be described.

FIG. 4 schematically shows a plane of an example of the master information carrier 2, and as shown in FIG. 4, one main surface of the master information carrier 2, that is, the side in contact with the ferromagnetic thin film surface of the hard disk 1. The signal area 2 is substantially radially
a is formed.

FIG. 5 schematically shows an enlarged view of a portion C surrounded by a dotted line in FIG. As shown in FIG. 5, in the signal area 2a, a digital information signal to be recorded on the hard disk 1, for example, a magnetic portion made of a ferromagnetic thin film in a pattern shape corresponding to the information signal is provided at a position corresponding to preformat recording. A master information pattern is formed. In FIG. 5, a hatched portion is a magnetic portion composed of a ferromagnetic thin film. The master information pattern shown in FIG. 5 is obtained by sequentially arranging respective areas of a clock signal, a tracking servo signal, an address information signal, and the like in the track length direction. The master information pattern shown in FIG. 5 is an example, and the configuration, arrangement, and the like of the master information pattern are appropriately determined according to the digital information signal recorded on the hard disk 1.

For example, in a hard disk drive, when a reference signal is first recorded on a magnetic film of the hard disk, and a preformat recording of a tracking servo signal or the like is performed based on the reference signal, the master information carrier is used to record the reference signal. Only the reference signal used for preformat recording is transferred and recorded on the magnetic film in advance, and the hard disk is built into the drive housing, and preformat recording such as servo signals for tracking is performed using the magnetic head of the hard disk drive It may be performed. In this case, the final preformat recording is performed by a magnetic head mounted in the drive as in the conventional method. However, the drive itself can complete the final preformat recording by referring to the reference signal transferred and recorded without using an expensive dedicated servo recording device. As with direct transfer recording,
The cost merit is greater than the conventional method.

FIG. 6 is a partial cross section of the region shown in FIGS.
Shown in As shown in FIG. 6, the master information carrier 2
A plurality of fine array patterns corresponding to information signals are formed on one main surface 10b of a disk-shaped base 10 made of a nonmagnetic material such as an i-substrate, a glass substrate, or a plastic substrate, that is, on the surface on the side where the surface of the hard disk 1 contacts Recess 10 in shape
a, and the ferromagnetic thin film 11, which is a magnetic part, is formed in the recess 10a of the base 10 so as to be embedded therein. Here, in order to uniformly adhere the hard disk 1 and the master information carrier 2 to obtain good recording characteristics using the recording apparatus shown in FIG. 1, the surface 11a of the ferromagnetic thin film 11 should be as flat as possible and One main surface 1 of 10
It is preferable to adopt a configuration protruding from 0b.

As the ferromagnetic thin film 11, a hard magnetic material,
Any type of magnetic material can be used regardless of a semi-hard magnetic material or a soft magnetic material, as long as a digital information signal can be transferred and recorded on a magnetic recording medium (hard disk). For example, Fe, Co, an Fe—Co alloy, or the like can be used. In order to generate a sufficient recording magnetic field irrespective of the type of the magnetic recording medium on which the information signal is recorded, the larger the saturation magnetic flux density of the magnetic material, the better. In particular, for a magnetic disk having a high coercive force exceeding 2000 Oersted (159 kA / m) or a flexible disk having a large magnetic layer thickness, the saturation magnetic flux density is not more than 0.2.
If it is less than 8 Tesla, sufficient recording may not be performed in some cases. Therefore, generally, a magnetic material having a saturation magnetic flux density of 0.8 Tesla or more, preferably 1.0 Tesla or more is used.

The thickness of the ferromagnetic thin film 11 depends on the bit length, the saturation magnetization of the magnetic recording medium and the thickness of the magnetic layer. For example, the bit length is about 1 μm, and the saturation magnetization of the magnetic recording medium is about 50 μm.
0 emu / cc (500 kA / m), and 50 nm to 500 nm when the thickness of the magnetic layer of the magnetic recording medium is about 20 nm.
It may be about nm.

Here, in such a recording method, in order to obtain good recording signal quality, based on an arrangement pattern shape of a soft magnetic thin film or a semi-hard magnetic thin film as a ferromagnetic thin film provided on a master information carrier. At the time of preformat recording, it is desirable to excite this to uniformly magnetize, and it is desirable to uniformly DC erase a magnetic recording medium such as a hard disk prior to signal recording using a master information carrier.

Next, a procedure for recording an information signal corresponding to the pattern shape formed on the master information carrier on a hard disk which is a disk-shaped magnetic recording medium will be described.

First, as shown in FIG.
The hard disk 1 is rotated in parallel with the hard disk 1 with the central axis of the hard disk 1 as a rotation axis while the hard disk 1 is brought close to the hard disk 1, thereby preliminarily magnetizing the hard disk 1 in one direction as indicated by an arrow in FIG. 8 (initial magnetization).

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, so that the master information carrier 2 passes through the center hole 1 a of the hard disk 1. Is sucked, and the surface of the master information carrier 2 on which the ferromagnetic thin film 11 is formed and the hard disk 1 are superimposed so as to be in close contact with each other.

Thereafter, as shown in FIG. 9, the magnetic field applied by the magnetizing head 6 is set to have the opposite polarity to the initial magnetization, and the center of the hard disk 1 held by the disk holder 3 is rotated. A DC excitation magnetic field is applied to the master information carrier 2 by rotating the magnetization head 6 in parallel with the master information carrier 2 as a center. Thereby, the ferromagnetic thin film 11 of the master information carrier 2 is magnetized,
Then, an information signal corresponding to the pattern shape of the magnetic part by the ferromagnetic thin film 11 is recorded in a predetermined area 1b of the hard disk 1 superimposed on the master information carrier 2, as shown in FIG. The arrow shown in FIG. 10 indicates the direction of the magnetization remaining outside the area 1b of the hard disk 1 where the information signal is recorded.

FIG. 11 shows in detail the state of magnetization when recording an information signal. As shown in FIG. 11, a magnetic field is applied to the master information carrier 2 from the outside to magnetize the ferromagnetic thin film 11 in a state where the master information carrier 2 is in close contact with the hard disk 1 as a magnetic recording medium. The information signal can be recorded on the magnetic recording layer 1c composed of the ferromagnetic thin film of the above. That is, by using the master information carrier 2 formed by forming a ferromagnetic thin film 11 in a predetermined pattern shape on a non-magnetic base 10, digital information signals can be transferred to the hard disk 1 as a magnetic recording medium.
Can be transferred and recorded magnetically.

Here, the transfer recording method will be described in more detail. FIG. 12 shows the above-described preformat recording process. FIG. 12A shows a DC erasing process of the hard disk 1 as a magnetic recording medium, and FIG. 12B shows an information signal recording process using the master information carrier 2. And (c) show the residual magnetization state of the hard disk 1 after preformat recording by a cross section in the information signal track length direction, respectively. When the magnetic recording medium is a hard disk, the information signal track length direction coincides with the disk circumferential direction.

As shown in FIG. 12A, the magnetic recording layer 1c on the hard disk 1 has a magnetization 13 in a certain direction by the DC erasing magnetic field 12 prior to the transfer and recording of the information signal using the master information carrier 2. DC erasure is performed uniformly. Next, as shown in FIG. 12B, the surface of the master information carrier 2 on which the ferromagnetic thin film 11 is formed in an array pattern shape corresponding to the information signal is placed on the magnetic recording layer 1c on the hard disk 1, which is a magnetic recording medium. And the ferromagnetic thin film 11 is excited by a DC exciting magnetic field 14 from the magnetizing head 6. At this time, the polarity of the DC exciting magnetic field 14 is
The polarity is opposite to the DC erasing magnetic field 12. Thereby, the magnetization 13 on the hard disk 1 is reversed by the leakage magnetic flux 15 only in the portion between the ferromagnetic thin films 11. As a result, after removing the master information carrier 2, a pattern of the magnetization 13 corresponding to the arrangement pattern shape of the ferromagnetic thin films formed on the master information carrier 2 can be recorded on the hard disk 1.

As described above, in the method of transfer recording from the master information carrier to the magnetic recording medium according to the present invention, the master information carrier has an arrangement pattern shape corresponding to a predetermined digital information signal to be recorded on the magnetic recording medium. First, a magnetic section made of a ferromagnetic thin film is formed in advance, a magnetic recording medium is brought into contact with the master information carrier, and the arrangement pattern shape formed on the master information carrier is transferred and recorded as a magnetization pattern. In such a method, it is important to reliably and accurately transfer the arrangement pattern of the magnetic portions formed on the master information carrier as the corresponding magnetization pattern.

However, when the present inventors performed preformat recording on a magnetic recording medium such as a hard disk using the above-described configuration, depending on various conditions at the time of preformat recording, the reproduction signal quality deteriorated, Alternatively, a phenomenon of unknown cause, which changes unstable depending on the position on the magnetic recording medium, was observed. If such deterioration of the reproduction signal quality occurs, it may become difficult to perform servo tracking of the magnetic recording and reproduction apparatus using the preformat recording signal.

In some cases, such a deterioration phenomenon of the signal quality can be prevented to some extent by experimentally optimizing various conditions at the time of preformat recording. However, when mass-producing a magnetic recording / reproducing apparatus using the above-described preformat recording technology, from the viewpoint of product quality assurance and improvement of production yield, a certain wide allowable range of preformat recording conditions is required. A range is needed. Under the appropriate recording conditions derived by trial and error experimental methods in the current preformat recording technology, the allowable range allowed from the viewpoint of signal quality is very narrow, and product quality assurance during mass production and production yield It is hard to say that it is sufficiently practical from the viewpoint of improvement.

The present inventors have repeatedly conducted various experiments and studies on this problem, and as a result, have found that the above signal quality deterioration phenomenon is caused by the following effects.

The length of each ferromagnetic thin film pattern on the master information carrier 2 in the circumferential direction of the disk as shown in FIGS. 4 and 5 is determined by reproducing the information recorded and recorded by using the magnetic head. The signal is designed to obtain a predetermined pulse interval on the time axis. However, since the rotational speed of the magnetic disk transferred and recorded in the hard disk drive is constant, the peripheral speed at one point on the disk is greater at the outer periphery of the disk than at the inner periphery of the disk. Therefore, in order to obtain a constant pulse interval from the inner circumference to the outer circumference in a signal waveform when a certain transferred and recorded signal is reproduced by the magnetic head, the length of the ferromagnetic thin film pattern in the circumferential direction of the disk is set closer to the outer circumference. It needs to be bigger. That is, with reference to the cross-sectional view of FIG. 6, in order to obtain a constant pulse interval for a certain signal, each ferromagnetic thin film 1 on the master information carrier 2
The length of one and the interval between the individual ferromagnetic thin films 11 are larger on the outer peripheral side than on the inner peripheral side.

On the other hand, since the ferromagnetic thin film 11 is deposited at a constant film forming rate using a sputtering method or the like, its film thickness is generally constant regardless of the inner peripheral side and the outer peripheral side. . That is, the cross section of each ferromagnetic thin film 11 has an elongated shape in which the ratio of length to film thickness (= length / film thickness) is smaller toward the inner periphery, and larger in the outer periphery.

In the ferromagnetic thin film patterns having different cross-sectional shapes as described above, when a DC excitation magnetic field 14 is applied as shown in FIG. The process and the transfer recording characteristics to the disk-shaped magnetic recording medium differ. That is, when the magnetic characteristics of the disk-shaped magnetic recording medium are uniform over the entire surface of the disk, the value of the DC excitation magnetic field 14 that obtains the optimum value in the leakage magnetic flux 15 contributing to the magnetization reversal and obtains the optimum value in the transfer recording characteristics is: It differs depending on the radial position of the disk-shaped magnetic recording medium. For this reason, when transfer recording is performed in the DC excitation magnetic field 14 in which good signal quality can be obtained on the inner circumference side, the signal quality on the outer circumference side is below the allowable limit, or conversely, good signal quality on the outer circumference side When the transfer recording is performed in the DC excitation magnetic field 14 capable of obtaining the following, a phenomenon occurs in which the signal quality on the inner peripheral side deteriorates below an allowable limit.

The present inventors have examined the above phenomenon in more detail, and as a result, have come to clarify the magnetic mechanism for making the optimum DC exciting magnetic field value different at the disk radial position as follows.

That is, the outer peripheral pattern having a large ratio of length to film thickness (= length / film thickness) has a small demagnetizing field in the direction in which the DC exciting magnetic field 14 is applied, and thus tends to reach saturation at a smaller magnetic field value. Conversely, the inner circumferential pattern having a small ratio of length to film thickness has a larger demagnetizing field in the direction in which the DC excitation magnetic field 14 is applied than the outer circumferential pattern. For this reason, in order to obtain the same value in the leakage magnetic flux 15 contributing to the magnetization reversal in the region corresponding to the region between the ferromagnetic thin films on the hard disk 1, a larger DC excitation magnetic field is required at the inner periphery than at the outer periphery. . As described above, when the transfer recording is performed using the DC excitation magnetic field that can obtain the optimum leakage magnetic flux 15 on the outer circumference and obtain the optimum signal quality, the area corresponding to the inner circumferential side between the ferromagnetic thin films is sufficient. The magnetization reversal cannot be obtained, and the signal quality deteriorates. Conversely, when transfer recording is performed using a DC excitation magnetic field that can obtain an optimum leakage magnetic flux 15 at the inner circumference and obtain an optimum signal quality, the ferromagnetic thin film 11 on the outer circumference reaches saturation. That is, the application of the DC exciting magnetic field 14 generates a magnetic flux having a polarity opposite to that of the initial magnetization of the hard disk 1 on the ferromagnetic thin film 11, and degrades or erases the initial magnetization, thereby deteriorating the signal quality.

As described above, it has been found that the optimum value of the DC excitation magnetic field to be applied to the hard disk 1 by the magnetic flux leaking from the magnetization head 6 is larger on the inner circumferential side than on the outer circumferential side. According to the present invention, the magnetic field applied to the master information carrier 2 by the magnetic flux leaking from the magnetizing head 6 is configured such that the applied magnetic field on the outer peripheral side of the hard disk 1 is smaller than the applied magnetic field on the inner peripheral side. I do. As a result, a sufficient magnetization reversal is obtained on the inner peripheral side, and the generation of the reverse polarity leakage magnetic flux on the ferromagnetic thin film is suppressed to an allowable range or less on the outer peripheral side,
Good signal quality can be obtained regardless of the disk radius position.

The present inventors have a configuration in which the magnetic field applied to the master information carrier 2 by the magnetic flux leaking from the magnetizing head 6 is such that the applied magnetic field on the outer peripheral side of the hard disk 1 is smaller than the applied magnetic field on the inner peripheral side. Of the magnetizing head 6 and the magnetic recording method using the same can be realized relatively easily and inexpensively.

That is, in the magnetic recording medium manufacturing method of the present invention, by using the magnetizing head 6 having a specific configuration and shape, the magnetic flux applied from the magnetizing head 6 is applied to the master information carrier 2. About the magnetic field,
It is possible to configure so that the applied magnetic field on the outer peripheral side of the hard disk 1 is smaller than the applied magnetic field on the inner peripheral side.

The magnetic field applied to the magnetizing head 6 used in the method of manufacturing the magnetic recording medium of the present invention, that is, the magnetic field applied to the master information carrier 2 will be described below. A configuration of the magnetizing head 6 for making the head smaller than the magnetic field will be described.

(Embodiment 2) FIG. 13 shows an example of a magnetizing head according to the present invention. FIG. 13 shows a master information carrier of a magnetizing head 6 formed by forming a ring-shaped magnetic circuit having a gap 6d by facing a first magnetic core half 6b and a second magnetic core half 6c. FIG. 3 is a plan view showing one main surface on a side facing 2. In the magnetizing head 6 shown in FIG. 13, the gap length G _O at the position corresponding to the outer peripheral side of the hard disk 1 is larger than the gap length G _I at the position corresponding to the inner peripheral side of the hard disk 1. It is configured. With such a configuration, the first magnetic core half 6b and the second magnetic core half 6c
Is uniformly excited, the magnetic field applied to the master information carrier 2 by the magnetic flux leaking from the magnetizing head 6 is shifted to a position corresponding to the outer peripheral side of the hard disk 1 at a position corresponding to the inner peripheral side. It can be configured to be smaller than that.

In the magnetizing head 6 shown in FIG. 13, a cross section parallel to the annular magnetic path of the magnetic circuit, that is, a cross section in the track length direction of the information signal, for example, in the circumferential direction of the hard disk 1 as a disk-shaped magnetic recording medium. FIG. 14 shows an example.
Shown in

FIG. 14 shows an example in which both or one of the first magnetic core half 6b and the second magnetic core half 6c is made of a permanent magnet material in addition to the configuration of FIG.
First magnetic core half 6b and second magnetic core half 6c
Or both of them are uniformly magnetized in a direction along the annular magnetic path of the magnetic circuit formed by them. This first
The permanent magnetic material forming at least one of the magnetic core half 6b and the second magnetic core half 6c is preferably a material having a residual magnetic flux density of 1.0 Tesla or more and a coercive force of 10,000 Oe (796 kA / m) or more. . As permanent magnets having such characteristics, Nd-Fe-B and Sm-
A rare earth magnet mainly containing a material such as Co can be used.

A section parallel to the annular magnetic path of the magnetic circuit in the magnetizing head 6 shown in FIG. 13, that is, a section in the track length direction of the information signal, for example, in the circumferential direction of the hard disk 1 which is a disk-shaped magnetic recording medium. Another example is shown in FIG.

In the example shown in FIG. 15, in addition to the structure shown in FIG. 13, at least one of the first magnetic core half 6b and the second magnetic core half 6c is provided with a winding 6a for DC exciting them. Is arranged. In the example of FIG. 15, the winding 6a is provided on the second magnetic core half 6c side.

In the embodiment shown in FIG. 14, the first magnetic core half 6b and the second magnetic core half 6c each having a yoke shape are uniformly arranged in the direction along the annular magnetic path of the magnetic circuit formed by these. However, depending on the shape of the core, it may be difficult to uniformly magnetize in the direction along the annular magnetic path. On the other hand, in the configuration of the example shown in FIG. 15, since the core is excited by the winding current, the material forming the first and second magnetic core halves 6b and 6c may not be a permanent magnet material. Various types of ferromagnetic materials having soft magnetism or semi-hard magnetism can be used. That is, a permanent magnet need not be provided as a component of the magnetic core, and the trouble of magnetizing in an appropriate direction can be eliminated.

A section parallel to the annular magnetic path of the magnetic circuit in the magnetizing head 6 shown in FIG. 13, that is, a section in the track length direction of the information signal, for example, in the circumferential direction of the hard disk 1 which is a disk-shaped magnetic recording medium. Another example is shown in FIG.

In this embodiment, in addition to the above configuration, the first magnetic core half 6b and the second magnetic core half 6c
Are opposed to each other via a permanent magnet 6e.

Accordingly, in the configuration shown in FIG. 16, the material forming the first and second magnetic core halves 6b and 6c is not a permanent magnet material but a strong magnetic material having various kinds of soft magnetism or semi-hard magnetism. Magnetic materials can be used. The first and second magnetic core halves 6b, 6c
The ferromagnetic material constituting the magnetic field does not cause significant magnetic saturation locally due to the magnetic flux supplied from the permanent magnet 6e.
It is preferable to have a sufficiently high saturation magnetic flux density. In the present embodiment, Fe, Fe-Co alloy, Fe-Si
Soft magnetic alloy materials are used.

As described above, in the embodiment shown in FIG. 14, the yoke-shaped first and second magnetic core halves are uniformly arranged in the direction along the annular magnetic path of the magnetic circuit formed by them. Magnetization is required, but depending on the core shape, it may be difficult to uniformly magnetize in the direction along the annular magnetic path.

On the other hand, in the configuration shown in FIG. 16, only the permanent magnet 6e is along the annular magnetic path of the magnetic circuit constituted by the first magnetic core half 6b and the second magnetic core half 6c. 16, that is, in FIG. 16, the magnets may be uniformly magnetized in the lateral direction of the paper.
Usually a block type rectangular parallelepiped shape can be used,
Compared to the magnetizing head illustrated in FIG. 14, the head can be manufactured easily and at low cost.

In the configuration shown in FIG. 16, the permanent magnet 6e used as a part of the annular magnetic path is preferably at least 1.0 Tesla in residual magnetic flux density and 10,000 Oersted (coercive force) as in the magnetic core in the above configuration. 796 kA /
m) or more. In addition, as a permanent magnet having such characteristics, a rare earth magnet mainly containing a material such as Nd—Fe—B or Sm—Co can be used.

The magnetizing head 6 illustrated in FIGS. 13 to 16 exhibits the effects of the present invention by being used in the transfer recording process illustrated in FIG. In the erasing process, the effect is not necessarily exerted. Therefore, in the DC erasing process illustrated in FIG. 7, the magnetizing head having the conventional configuration illustrated in FIG. 3 can be used. That is, even in this case, the effects of the present invention can be sufficiently obtained as long as the magnetizing head having the structure of the present invention is used in the transfer recording process illustrated in FIG.

The embodiment of the magnetizing head 6 used in the method of manufacturing a magnetic recording medium according to the present invention has been described above. The spacing between the magnetizing head 6 and the hard disk 1 is set to an appropriate range. By doing so, the magnetizing head 6
With respect to the magnetic field applied to the master information carrier 2 by the magnetic flux leaking from the hard disk 1, the applied magnetic field on the outer peripheral side of the hard disk 1 can be configured to be smaller than the applied magnetic field on the inner peripheral side. Since the allowable range of the spacing between the magnetic head 6 and the hard disk 1 can be sufficiently widened, the magnetizing head 6 is moved relative to the master information carrier 2 in the process of transferring and recording the information signal. When moving, even if a certain amount of fluctuations in spacing occur, a high-quality reproduced signal can be obtained stably, and a sufficient performance margin can be obtained from the viewpoint of quality assurance of products during mass production and improvement in production yield. Preformat recording can be performed.

Further, in the above description, the description has been made with a primary focus on application to a hard disk mounted on a hard disk drive or the like as a magnetic recording medium. However, the present invention is not limited to this. The present invention can be applied to a disk-shaped magnetic recording medium such as a flexible magnetic disk, and the effects of the invention can be obtained in the same manner as described above. Disc-shaped magnetic recording medium In addition, regarding the information signal recorded on the magnetic recording medium, description has been made with a focus on a pre-format signal such as a tracking servo signal, an address information signal, and a reproduction clock signal. The information signal to which the configuration can be applied is not limited to the above. For example, it is possible in principle to record various data signals, audio and video signals using the configuration of the present invention. In this case, the method for manufacturing a magnetic recording medium of the present invention enables mass copying and production of soft disk media.

[0116]

As described above, according to the present invention, a pattern corresponding to an information signal on a master information carrier for a magnetic recording medium, particularly a disk-shaped magnetic recording medium such as a fixed hard disk medium, a removable hard disk medium, and a large-capacity flexible medium. Can be uniformly and stably performed over the entire surface of the magnetic recording medium. In other words, high-density information signals can be magnetically transferred and recorded in a short time with high reliability and high productivity.

In addition, when the information signal of the master information carrier is transferred and recorded on the magnetic recording medium, the quality of the transferred and recorded signal is not degraded, and the quality of the product during mass production and the improvement of the production yield are improved. From a viewpoint, it is possible to provide a recording technique with sufficiently excellent signal quality.

In particular, when the magnetic transfer of the pattern corresponding to the information signal on the master information carrier to the magnetic recording medium is performed uniformly and stably over the entire surface of the magnetic recording medium, the gap length becomes closer to the outer peripheral side of the magnetic recording medium. A great improvement can be achieved by a simple improvement of using a magnetizing head having a large gap.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an outline of an example of an apparatus for performing signal recording on a magnetic recording medium according to a first embodiment of the present invention;

FIG. 2 is a perspective view schematically showing a magnetizing head according to the first embodiment.

FIG. 3 is a plan view showing one main surface of the magnetization head according to the first embodiment facing the master information carrier (the same applies to the conventional example).

FIG. 4 is a plan view showing an example of a master information carrier used in the recording method of the present invention.

FIG. 5 is an explanatory diagram for explaining an example of an arrangement pattern of information signals formed on a master information carrier.

FIG. 6 is a sectional view showing an example of a master information carrier according to the present invention.

FIG. 7 is a perspective view showing a state where a one-way magnetic field is applied to a hard disk in the recording method according to the present invention.

8 is a perspective view schematically showing a state of a hard disk that is magnetized in one direction by the process shown in FIG. 7;

FIG. 9 is a perspective view showing a state where an information signal is transferred and recorded on a hard disk by the recording method according to the present invention.

FIG. 10 is a perspective view schematically showing a state of the hard disk on which the information signal is recorded by the process shown in FIG. 9;

FIG. 11 is an explanatory diagram for explaining a state of a magnetization pattern when an information signal is transferred and recorded on a hard disk by the process shown in FIG. 9;

FIG. 12 is a schematic diagram showing a preferable recording state of preformat recording using a master information carrier in the present invention.

FIG. 13 is a plan view showing one main surface of a magnetizing head used in the recording method according to the present invention, the main surface facing a master information carrier;

FIG. 14 is a perspective view showing an example of a configuration when a magnetizing head used in the recording method of the present invention is arranged so as to face a master information carrier.

FIG. 15 is a sectional view showing another example of the magnetizing head used in the recording method of the present invention.

FIG. 16 is a sectional view showing another example of the magnetizing head used in the recording method of the present invention.

[Description of Signs] 1 Hard disk 2 Master information carrier 2a Signal area 6 Magnetizing head 6a Winding 6b First magnetic core half 6c Second magnetic core half 6d Gap 6e Permanent magnet 10 Non-magnetic base 11 Strong Magnetic thin film

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[Procedure amendment]

[Submission date] September 18, 2002 (2002.9.1)
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[Procedure amendment 1]

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Patent application title: Method of Manufacturing Magnetic Recording Medium and Magnetizing Head for Manufacturing Magnetic Recording Medium

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[Claims]

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[0001]

The present invention relates to a method for manufacturing a magnetic recording medium, and more particularly to a technique for recording a predetermined information signal on a magnetic recording medium used in a magnetic recording / reproducing apparatus. The present invention also relates to a magnetizing head used in a method for manufacturing a magnetic recording medium .

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──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/84 G11B 5/84 Z (72) Inventor Hideyuki Hashi 1006 Kazuma Kazuma, Kadoma City, Osaka Matsushita Electric Industrial F term in the company (reference) 5D093 AA03 AD07 BB04 CA07 EA05 EA12 5D111 AA14 AA24 BB12 CC03 KK20 5D112 DD09

Claims (13)

[Claims] 1. A magnetizing head in which a first magnetic core half and a second magnetic core half are opposed to each other with a gap in a state where a master information carrier is superimposed on a disk-shaped magnetic recording medium. A method for manufacturing a magnetic recording medium, wherein a pattern corresponding to an information signal on the master information carrier is magnetically transferred to the magnetic recording medium with a leakage magnetic flux from the magnetic part by magnetizing a magnetic part of the master information carrier. Magnetizing the master information carrier for the magnetic transfer using a magnetizing head configured such that the gap length increases toward the outer periphery of the magnetic recording medium as the magnetizing head. Recording medium manufacturing method. 2. A magnetizing head, wherein at least one of the first magnetic core half and the second magnetic core half is made of a permanent magnet is used as the magnetizing head. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein: 3. The magnetizing head according to claim 1, wherein the first magnetic core half and the second magnetic core half are joined together with a permanent magnet interposed therebetween. 2. The method according to claim 1, wherein the magnetic recording medium is used. 4. A magnetizing head in which at least one of the first magnetic core half and the second magnetic core half has a DC excitation winding as the magnetizing head. The method for manufacturing a magnetic recording medium according to claim 1, wherein: 5. A step of applying a DC erasing magnetic field to the magnetic recording medium to magnetize the magnetic recording medium in a fixed direction prior to the magnetic transfer step, wherein the master information carrier is placed on the magnetized magnetic recording medium. In the step of magnetic transfer in the superimposed state, by applying a magnetic field having a polarity opposite to that of the DC erasing magnetic field to the magnetic portion of the master information carrier using the magnetizing head, 5. The method according to claim 1, wherein a pattern corresponding to an information signal is magnetically transferred to the magnetic recording medium. 6. An annular magnetic path having a gap with a first magnetic core half and a second magnetic core half facing each other as a magnetizing head for applying a DC erasing magnetic field to the magnetic recording medium. 6. A method according to claim 5, wherein a magnetizing head having a substantially uniform gap length in a radial direction of the magnetic recording medium is used. 7. A magnetic recording apparatus according to claim 1, wherein the gap facing the main surface of the head facing the master information carrier is formed in such a manner that the gap length is monotonously and continuously increased gradually toward the outer periphery of the magnetic recording medium. Magnetizing head for manufacturing media. 8. A first magnetic core half and a second magnetic core half are joined in a gap formation state, and a gap facing a head main surface facing a master information carrier has a gap length. A magnetizing head for manufacturing a magnetic recording medium, wherein the head is monotonously and continuously formed in a shape that becomes larger toward the outer peripheral side of the magnetic recording medium. 9. The magnetic recording medium according to claim 8, wherein at least one of the first magnetic core half and the second magnetic core half is made of a permanent magnet. Magnetizing head. 10. The magnetic device according to claim 8, wherein the first magnetic core half and the second magnetic core half are joined with a permanent magnet interposed therebetween. Magnetizing head for manufacturing recording media. 11. The magnetic device according to claim 8, wherein at least one of the first magnetic core half and the second magnetic core half includes a DC excitation winding. Magnetizing head for manufacturing recording media. 12. A magnetic recording medium manufactured by the method of manufacturing a magnetic recording medium according to claim 1, wherein a magnetic pattern of a predetermined information signal magnetization pattern is magnetically transferred in advance to a magnetic film. A hard disk drive characterized by comprising: 13. A magnetic recording medium comprising a built-in magnetic recording medium that has been preformat-recorded by using the magnetic recording medium manufacturing method according to any one of claims 1 to 6. Playback device.