JP3323743B2 - Method for manufacturing master information carrier and magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording an information signal on a magnetic recording medium used in a high-capacity, high-density magnetic recording / reproducing apparatus, and a master information carrier having the information signal to be recorded.

[0002]

2. Description of the Related Art At present, magnetic recording / reproducing apparatuses tend to have a high 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 with surface recording densities exceeding 1 Gbit / in2 have already been commercialized, and in a few years, they will be so rapid that practical application of 10 Gbit / in2 will be discussed. Technical progress is recognized.

[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 increasing the track density greatly exceeds the trend of increasing the linear recording density, and is a main factor for improving the areal recording density. This is due to the practical use of a magnetoresistive element type head which is much more excellent in reproduction output performance than a conventional inductive 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 with good SN. On the other hand, it is expected that the track pitch will reach the submicron range in the near future with further improvement in head performance in the future.

In order for a head to accurately scan such a narrow track and reproduce a signal with good SN, the tracking servo technique of the head plays an important role. Regarding such tracking servo technology, for example, “Yamaguchi: High-precision servo technology for magnetic disk devices,
Journal of the Japan Society of Applied Magnetics, Vol.20, No.3, pp.771, (1996) "
The detailed contents are shown in FIG. According to the above-mentioned literature, in a current hard disk drive, an area in which 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, 360 degrees in angle. (Hereinafter, referred to as a 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, reproduction clock signal, and the like serve as reference signals for the head to accurately scan the track. Required. For example, "Uematsu, et al .: Mechanical Servo, Current Status and Prospects of HDI Technology, 93rd Research Meeting of the Japan Society of Applied Magnetics, 93
-5, pp.35 (1996) ", the current hard disk drive incorporates a disk into the drive, and then uses a dedicated servo recording device to control the position of the magnetic head with strict position control. Preformat recording is being performed.

[0006] Such preformat recording of a servo signal, address information signal, and reproduction clock signal is also performed in a special-purpose medium such as a large-capacity flexible disk commercialized in recent years or a removable hard disk medium in which a disk cartridge is removable. This is performed by a magnetic head using a servo recording device.

[0007]

However, in the preformat recording of the servo signal, the address information signal, and the reproduced clock signal by the above method, there are the following problems.

First, as a first problem, recording by a magnetic head is basically line recording based on relative movement between a head and a 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.

This problem becomes more serious as the track density of the magnetic recording device increases. This is not only due to the increase in the number of tracks in the disk radial direction. The higher the track density, the higher the accuracy of head positioning is required.
In the meantime, it is necessary to reduce an angular interval at which a servo area in which a tracking servo signal or the like is recorded is provided. For this reason, the higher the recording density of the apparatus, the larger the amount of signals to be preformat-recorded, and more time is required.

Although magnetic disk media tend to be smaller in diameter, there is still a great demand for 3.5-inch and 5-inch large-diameter disks. It is inevitable that the larger the recording area of the disk, the larger the amount of signals to be preformat-recorded. The cost required for preformat recording also greatly contributes to the cost performance of such a large-area disk.

The second problem is that the magnetic transition at the end of the track on which preformat recording is performed lacks sharpness due to the spacing between the head and the medium and the spread of the recording magnetic field due to the pole shape of the recording head.

Since the recording by the magnetic head is basically a dynamic linear recording based on the relative movement between the head and the medium, a certain amount of head-medium spacing is required from the viewpoint of the interface performance between the head and the medium. I have to provide it.
In addition, the current magnetic head generally has a structure having two elements that separately perform recording and reproduction, so that the leading edge side pole width of the recording gap is equal to the recording track width, while the trailing edge side pole width is equal to the recording track width. More than several times larger.

Both of the above two points cause a spread of the recording magnetic field at the end of the recording track, and as a result, the magnetization transition at the end of the track on which the preformat recording is performed lacks sharpness, or both sides of the track end. This results in a problem that an erasure area is generated in the image. 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, not only is the SN excellent when the head accurately scans the track as in reproducing the data information signal recorded between the servo areas, but also the reproduction output change when the head scans off the track. The amount, that is, the off-track characteristic is required to be steep. The above-mentioned problem is contrary to this requirement, and makes it difficult to realize an accurate tracking servo technique in future submicron track recording.

As a solution to the former of the above two problems, for example, Japanese Patent Application Laid-Open No. 63-183623 discloses a copying technique such as a tracking servo signal using a magnetic transfer technique. It is true that the use of such a magnetic transfer technique improves the productivity in preformat recording. However, the above technique is effective for a magnetic disk medium having a relatively low coercive force and a low areal recording density, such as a flexible disk, but has an area recording density of several hundred megabits to a gigabit order as in today's hard disk medium. It cannot be used for high coercivity media with the required resolution. In the magnetic transfer technology, it is necessary to apply an AC bias magnetic field having an amplitude of about 1.5 times the coercive force of the transferred disk in order to secure transfer efficiency. Since the master information recorded on the master disk is a magnetized pattern, in order to prevent the master information from being demagnetized by the AC bias magnetic field, the coercive force of the master disk must be at least about three times the coercive force of the transferred disk. It is required. The coercive force of the current high-density hard disk medium ranges from 1500 to 2500 Oersted in order to play a high areal recording density. 10 in the future
This value is expected to reach 3000 to 4000 Oersted in order to achieve a surface recording density of the gigabit order. In other words, 4500 ~
A coercive force of 7500 Oersted, and in the future 9000-12000 Oersted, will be required. It is difficult to realize such a coercive force in the master disk from the viewpoint of selecting a magnetic material. Furthermore, with the current magnetic recording technology, there is no means for recording master information on the master disk itself having such a high coercive force. Therefore, in the magnetic transfer technology, considering the coercive force value that can be realized in the master disk, the coercive force of the transferred disk is necessarily limited.

According to Japanese Patent Application Laid-Open No. Hei 7-153060, for example, a disk medium substrate having irregularities corresponding to a tracking servo signal, an address information signal, a reproduction clock signal, and the like is formed by a stamper. A pre-embossed disk technique of forming a magnetic layer on a disc is disclosed. This technique is an effective solution to the two problems described above. However, it is expected that the unevenness of the disk surface will affect the flying characteristics of the head during recording / reproducing (or the contact state with the medium in the case of contact recording), causing a problem in the head-medium interface performance. Further, since the substrate manufactured by the stamper is basically a plastic substrate, there is a problem that the substrate cannot be heated at the time of forming the magnetic layer necessary for securing the medium performance, and the necessary medium SN cannot be secured. .

From the above technical background, a truly effective solution has been found for the two problems described above without sacrificing other important performances such as medium SN and interface performance. Absent.

[0017]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has been made in consideration of the productivity at the time of preformat recording and the preformat recording without sacrificing other important performances such as medium SN and interface performance. It is intended to provide a means for improving the steepness of the magnetization transition at the track end.

According to the present invention, in order to realize the above means, an uneven shape corresponding to an information signal is formed on the surface of a substrate, and the thickness of the uneven surface is at least 0.1 μm.
The surface of the master information carrier on which the ferromagnetic thin film of 1 μm is formed 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, thereby forming a surface of the master information carrier . It is characterized in that a magnetization pattern corresponding to the uneven shape is recorded on a magnetic recording medium. Preferably, in the recording process, a DC magnetic field for exciting a ferromagnetic material forming the surface of the convex portion of the master information carrier or an AC bias magnetic field for facilitating recording of a magnetization pattern is applied.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operation of the above-described configuration of the present invention will be described.

[0020] In the configuration of the present invention, the recording magnetic field generated from the ferromagnetic material of the master information carrier surface protrusions that are magnetized in one direction, the magnetic recording medium, the master information responsible
A magnetization pattern corresponding to the uneven shape of the body is recorded. That is, by forming irregularities corresponding to a tracking servo signal, an address information signal, a reproduction clock signal, and the like on the surface of the master information carrier , preformat recording corresponding to these can be performed on the magnetic recording medium. It is.

According to the present invention, recording is performed by using a leakage magnetic field generated from a ferromagnetic material in a convex portion due to a change in magnetoresistance due to an uneven shape. Therefore, from the viewpoint of the recording mechanism, it is the same as the recording by the conventional magnetic head, in which the recording is performed by the leakage magnetic field generated from the head recording gap. On the other hand, recording by the conventional magnetic head is basically dynamic linear recording based on the relative movement between the head and the medium, whereas the feature of the present invention does not involve the relative movement between the master information carrier and the medium. It is a static surface record. With the above features, the present invention can exert an extremely effective effect on the above-described two problems.

First, because of surface recording, the time required for preformat recording is very short as compared with the 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, according to the present invention, productivity related to preformat recording can be greatly improved, and production cost can be reduced.

Secondly, since static recording does not involve relative movement between the master information carrier and the medium, the surface of the master information carrier and the surface of the magnetic recording medium are brought into close contact with each other so as to allow the recording to be performed between the two. Can be minimized. Furthermore, unlike the recording by the magnetic head, the recording magnetic field does not spread due to the pole shape of the recording head. For this reason, the transition of the magnetization at the end of the track on which the preformat recording is performed has an excellent steepness as compared with the recording by the conventional magnetic head, and more accurate tracking is possible.

On the other hand, according to the present invention,
No. 623, JP-A 7-1.
There is no problem that the configuration and magnetic characteristics of a magnetic recording medium on which preformat recording is performed are restricted as recognized in the pre-embossed disk technology disclosed in Japanese Patent No. 53060.

For example, in the magnetic transfer technique disclosed in Japanese Patent Application Laid-Open No. 63-183623, a master disk provided with master information recorded by a magnetization pattern is a magnetic recording medium itself, and therefore has a corresponding magnetic recording medium. Requires medium resolution. For this reason, the magnetic flux density and the film thickness of the master disk magnetic layer cannot be made sufficiently large, and the magnitude of the generated transfer magnetic field becomes very small. Further, since the master information is recorded in a magnetization pattern, demagnetization occurs due to the butt magnetization of the dibit, and the transfer magnetic field gradient in the magnetization transition region is gentle. In order to ensure sufficient transfer efficiency even with such a weak transfer magnetic field, in the magnetic transfer technique, it is necessary to apply an AC bias magnetic field having an amplitude of about 1.5 times the coercive force of the transferred disk. As a result, as described above, the coercive force of the transferred disk is restricted,
It can be used only for a flexible disk or the like having a relatively low recording density.

On the other hand, the master information carrier of the present invention has the master information as an uneven pattern, and performs recording by using a leakage magnetic field generated from the ferromagnetic material of the convex portion due to a change in magnetoresistance due to the uneven shape. A recording element having a mechanism, similar to a magnetic head. Since the resolution as a magnetic recording medium is not required unlike the master disk in the magnetic transfer technology, the magnetic flux density and volume of the ferromagnetic material constituting the convex portion of the master information carrier surface should be increased to the same level as the conventional magnetic head. Accordingly, it is possible to generate a steep and large recording magnetic field as much as a magnetic head. As a result, it is possible to exhibit a sufficient recording capacity for all magnetic recording media, from ordinary flexible disks and hard disks to high coercive force media for gigabit recording in the future.

In the pre-embossed disk technology disclosed in Japanese Patent Application Laid-Open No. 7-153060, as described above, since the substrate material and shape of the disk medium on which the preformat recording is performed are restricted, the medium film formation is performed. The media SN performance related to the substrate temperature at the time and the flying characteristics of the head (or the contact state with the medium in the case of contact recording) related to the head-media interface performance have been sacrificed. On the other hand, in the configuration of the present invention, there is no restriction on the substrate material and surface shape of the magnetic recording medium on which preformat recording is performed as described above.

As described above, according to the configuration of the present invention, static surface recording can be performed regardless of the configuration and magnetic characteristics of a magnetic recording medium on which preformat recording is performed. A truly effective solution can be provided without sacrificing other important performances such as SN and interface performance.

In the recording process according to the method of the present invention, applying an AC bias magnetic field that attenuates with time is an effective means for further improving the recording efficiency. At this time, unlike the magnetic transfer technology in which the master information is recorded by using a magnetization pattern, the master information of the present invention is a pattern having an uneven shape, so that even when an external magnetic field such as an AC bias magnetic field is applied. The master information itself does not disappear. From this point of view, in the present invention, the coercive force value of the ferromagnetic material constituting the surface convex portion of the master information carrier is not greatly restricted. For this reason, as long as a sufficient recording magnetic field for recording master information on a magnetic recording medium can be generated, the ferromagnetic material constituting the master information carrier surface convex portion is not limited to a high coercive force material, An appropriate material can be selected from many materials having semi-hard magnetism or soft magnetism.

On the other hand, in the structure of the present invention, it is necessary that the ferromagnetic material constituting the convex portion is magnetized in one direction in the recording process to generate a recording magnetic field. Therefore, when stable unidirectional magnetization cannot be obtained in a configuration using a semi-hard magnetic material or a soft magnetic material, or when an AC bias magnetic field having a relatively large amplitude is applied, the ferromagnetic material is excited and A DC excitation magnetic field is separately applied to generate a proper recording magnetic field. This DC exciting magnetic field corresponds to the exciting magnetic field supplied by the winding current in the magnetic head.

Hereinafter, embodiments of the present invention will be described in detail. First, one configuration example of the master information carrier surface of the present invention is shown in FIG. FIG. 1 shows, for example, a master information pattern recorded in a preformat area provided at fixed angles in a circumferential direction (ie, a track length direction) of a disk-shaped magnetic recording medium, in a radial direction (ie, a track width direction) of the disk medium. 10 shows only 10 tracks. For reference, a track portion that becomes a data area on the disk medium after the master information pattern is recorded on the disk medium is indicated by a broken line. The actual master information carrier surface corresponds to the recording area of the magnetic disk medium on which the master information is recorded, at regular intervals in the circumferential direction of the disk, and for all recording tracks in the radial direction of the disk medium. A master information pattern such as described above is formed.

As shown in FIG. 1, for example, the master information pattern is formed by sequentially arranging a clock signal, a tracking servo signal, and an address information signal in the track length direction. In the master information carrier of the present invention, the master information pattern is formed by a surface uneven shape corresponding to the information pattern. For example, in FIG. 1, the hatched portion is a convex portion, and the surface is made of a ferromagnetic material.

The fine concavo-convex pattern corresponding to the information signal as shown in FIG. 1 can be easily formed by using various fine processing techniques used in, for example, a forming process of a master stamper for forming an optical disk or a semiconductor process. can do. In particular, a method of forming a fine concavo-convex pattern by dry etching after exposing and developing a resist film, such as a lithography technique using a laser beam or an electron beam, such as a photolithography method, is most suitable. Of course, as long as a fine concavo-convex pattern corresponding to the information signal is formed with high accuracy, it is possible to directly perform a fine processing by a laser, an electron beam, an ion beam, or other mechanical processing without using a resist film. A method may be used.

Next, FIG. 2 to FIG. 4 show examples of the configuration of the cross section in the track length direction of the master information carrier along the dashed line AA ′ shown in FIG.

FIGS. 2 and 3 show an example in which a ferromagnetic thin film 2 is formed on the surface of a flat substrate 1 and then a concavo-convex shape corresponding to a master information signal is formed. When forming the uneven shape, the ferromagnetic thin film 2 may be left on both the convex portion and the concave portion as shown in FIG. 2, or the bottom of the concave portion may be brought into the base 1 as shown in FIG. Only the ferromagnetic thin film 2 may be left.

FIG. 4 shows an example in which, unlike the configuration shown in FIGS. 2 and 3, an uneven shape is first formed on the surface of the substrate 1, and then the ferromagnetic thin film 2 is formed thereon.

In the configuration example shown in FIG. 4, the surface of the ferromagnetic thin film 2 has a curved shape at the boundary between the convex portion and the concave portion, and it is difficult to obtain a steep step. In this case, when recording the master information on the magnetic disk medium, it should be noted that the recording magnetic field gradient at the boundary between the convex portion and the concave portion may be reduced and the recording performance may be deteriorated.

On the other hand, the configuration examples of FIGS. 2 and 3 are generally more preferable than the configuration example of FIG. 4 because a steep recording magnetic field having a sufficiently large gradient is easily obtained at the boundary between the convex portion and the concave portion. . However, when forming the uneven shape,
Care must be taken so that no altered layer or resist film remains on the surface of the ferromagnetic thin film. This is because these cause a recording spacing loss when the master information is recorded on the magnetic disk medium.

The material of the substrate is not particularly limited as long as the ferromagnetic thin film 2 can be formed on the substrate and the concave and convex shape corresponding to the master information signal can be formed with high accuracy. A material having a small degree and as good a flatness as possible is preferable. This is because if the surface roughness is large, the surface roughness of the ferromagnetic thin film formed on the substrate also becomes large, which increases the recording spacing loss when recording master information on a magnetic disk medium.
Therefore, as a material capable of realizing a surface as flat as possible, for example, various glass substrates conventionally used as substrates for magnetic disks and optical disks, plastic substrates such as polycarbonate, metal substrates such as Al, An Si substrate or a carbon substrate is suitable.

With respect to the recording spacing loss, when recording master information on a magnetic disk medium, it is preferable that the surface of the master information carrier and the surface of the magnetic disk medium are in close contact with each other and are in good contact. In particular, when the magnetic disk on which the master information is recorded is a hard disk medium, the surface of the master information carrier can follow a slight undulation or bending of the surface of the magnetic disk medium to realize a good contact state over the entire surface of the disk. is necessary. For this reason, as the base material of the master information carrier ,
More or less flexible materials, such as a sheet-shaped or disk-shaped plastic substrate or a thin metal plate, are more preferable.

In the case where the configuration example of the cross section of the master information carrier shown in FIG. 4 is formed using a resist film,
Since a resist film is applied to the surface of the base of the master information carrier, a plastic substrate cannot generally be used as the base material. In this case, it is necessary to devise a method of separately forming a thin film on the surface of the base to form a buffer layer and forming a resist film on the buffer layer.

The depth of the concave portion in the configuration example of FIGS.
That is, the step between the surface of the projection and the bottom of the recess depends on the surface properties of the magnetic disk medium on which the master information is recorded and the bit size of the master information, but is generally 0.05 μm or more, preferably 0.1 μm or more. In particular, when the ferromagnetic material remains on the bottom surface of the concave portion as in the configurations of FIGS.
If the thickness is 0.1 μm or less, it is difficult to obtain a steep recording magnetic field having a sufficiently large gradient at the boundary between the convex portion and the concave portion. Also, when recording master information on a magnetic disk medium, the master
From the viewpoint of the contact state between the surface of the carrier and the surface of the magnetic disk medium, the range is preferably about 0.1 μm to 0.5 μm.

The formation of the ferromagnetic thin film 2 can be performed by using a conventional thin film forming method such as a sputtering method, a vacuum evaporation method, an ion plating method, and a CVD method.

As described above, the ferromagnetic thin film material may be a hard magnetic material, a semi-hard magnetic material, or a soft magnetic material.
Although many types of materials can be used, regardless of the type of magnetic disk medium on which master information is recorded,
In order to generate a sufficient recording magnetic field, the larger the saturation magnetic flux density is, the better. Especially for a high coercive force medium exceeding 2000 Oersted or a flexible disk medium having a large magnetic layer thickness, sufficient recording may not be performed if the saturation magnetic flux density is 0.8 T or less. As described above, preferably, a material having a saturation magnetic flux density of 1.0 T or more is used.

The thickness of the ferromagnetic thin film also affects the recording performance on the magnetic disk medium. Regardless of the type of magnetic disk medium, a ferromagnetic thin film must have a certain thickness or more to generate a sufficient recording magnetic field, but the effect of the demagnetizing field depends on the bit shape of the master information. Must also be considered. That is, in the configuration of the present invention, the recording is generally performed by magnetizing the ferromagnetic thin film of the convex portion of the master information carrier in the track direction in the film plane, except in a special case where the magnetic disk medium is a perpendicular magnetic recording medium. Generate a magnetic field. However, if the film thickness is too large, the leakage magnetic flux is reduced due to the influence of the demagnetizing field, resulting in a lack of recording capability. Therefore, it is necessary to set an appropriate value for the thickness of the ferromagnetic thin film according to the bit length of the master information. For example, when the shortest bit length of the master information is about 1 μm, a range from about 0.1 μm to about 1 μm is appropriate.

The preferable magnetic properties of these ferromagnetic materials will be separately described later in connection with the method of recording master information on a magnetic disk medium.

FIG. 5 shows another example of the cross section of the master information carrier along the dashed line AA ′ shown in FIG. FIG.
Is a configuration example in which the substrate itself is made of a ferromagnetic material, unlike the configuration examples of FIGS. That is, in the configuration of FIG. 5, the process of forming the ferromagnetic thin film can be omitted by forming the uneven shape corresponding to the master information signal on the surface of the base 3 made of the ferromagnetic material. The productivity of the master information carrier itself can be improved as compared with the configuration described above.

On the other hand, when a bulk material such as a sintered body is used as the ferromagnetic material base 3, the surface roughness of the master information carrier often becomes relatively large. In this case, when the master information is recorded on the magnetic disk medium, the recording spacing loss increases. Therefore, it is necessary to select a base material having as flat a surface property as possible. In general, flexibility cannot be realized in a bulk material such as a sintered body. Therefore, the configuration example of FIG. 5 is more suitable for recording on a flexible disk medium than on a hard disk medium.

Next, using the above-mentioned master information carrier ,
An embodiment of a method for recording a master information signal on a magnetic recording medium will be described.

FIG. 6 shows (a) a method of recording a master information signal on a longitudinal magnetic recording medium using a master information carrier , (b) a recording magnetization pattern recorded on the magnetic recording medium, and (c). The above recorded magnetization is converted to a magnetoresistive type (MR)
FIG. 5 shows an example of a signal waveform at the time of reproduction using a head. FIG. Note that both (a) and (b) are shown as configuration examples of the cross section in the track length direction of the magnetic recording medium.

When recording is performed on an in-plane magnetic recording medium, the ferromagnetic material constituting the convex portion of the master information carrier 4 has a track length parallel to the surface of the magnetic recording medium 5 as shown in FIG. The magnetization 6 is given in the direction of the vertical axis. For example, when the ferromagnetic material forming the protrusion is made of a material having a high coercive force, the magnetization 6 is given by the residual magnetization generated by DC-saturating the material in advance in the track length direction. In addition, as a high coercive force material suitable for the above ferromagnetic material, for example, rare earth-transition metal based materials including Sm-Co, Ne-Fe-B, etc. are large in both coercive force and saturation magnetic flux density. Are suitable.

The surface of the master information carrier 4 undergoes a change in magnetoresistance due to the unevenness, so that the magnetization
As a result, a recording magnetic field 7 is generated. Since the recording magnetic field 7 has opposite polarities on the surface of the convex portion and the surface of the concave portion of the master information carrier 4, as a result, the recording magnetization 8 corresponding to the uneven shape shown in FIG. Will be recorded.

As shown in (c), the reproduction wave shape from the recording magnetization recorded by using the conventional magnetic head is basically the same as the reproduction wave shape from the recording magnetization 8 by the recording method according to the present invention. The same is true. Therefore, there is no particular inconvenience in signal processing. Rather, according to the recording method of the present invention, the reproduction waveform is improved due to the fact that the symmetry of the recording magnetic field is better as compared with the recording by the magnetic head and the static recording without the relative movement of the master information carrier and the magnetic recording medium. Tend to have excellent symmetry.

In the recording process of the present invention, as described above, the recording efficiency can be further improved by applying an AC bias magnetic field that attenuates with time. In consideration of the technical field to which the present invention is applied, it is basically preferable to perform digital saturation recording in the recording method of the present invention. However, depending on the information signal pattern to be recorded and the magnetic characteristics of the magnetic recording medium, the recording capability may be slightly insufficient. In such a case, the application of the AC bias magnetic field that attenuates as time elapses,
This is an effective means to support sufficient saturation recording.

The recording mechanism by applying the AC bias magnetic field is basically the same as the conventional analog AC bias recording mechanism. However, the recording method of the present invention uses the master information
Since the static recording does not involve the relative movement between the carrier and the magnetic recording medium, the restriction on the frequency of the AC bias magnetic field is much smaller than that of the conventional analog AC bias recording. Therefore, the frequency of the AC bias magnetic field applied in the recording method of the present invention is, for example, a frequency of 50 Hz or 60 Hz used in a household AC power supply is sufficient.

The decay time of the AC bias magnetic field is sufficiently longer than the AC bias cycle, and
Set to a cycle or longer. For example, when the frequency of the AC bias magnetic field is 50 Hz or 60 Hz, the decay time is 100 m
It is sufficient if the length is about s or more.

On the other hand, in the configuration shown in FIG. 6, the maximum amplitude of the AC bias magnetic field needs to be smaller than the coercive force of the ferromagnetic material forming the convex portion of the master information carrier 4. When an AC bias magnetic field larger than the coercive force of the ferromagnetic material is applied in the configuration shown in FIG. 6, the magnetization 6 of the convex ferromagnetic material is reduced and a sufficient recording magnetic field 7 cannot be obtained.

The above description has focused on the case where the ferromagnetic material forming the convex portion of the master information carrier is made of a material having a high coercive force. However, when using a high coercive force material, depending on the concavo-convex pattern shape on the surface of the master information carrier , it is possible to provide an easy axis of the ferromagnetic material in the track length direction of the magnetic recording medium to obtain sufficient magnetization 6. It can be difficult.

For example, when the bit shape of the master information signal given by the convex portion of the master information carrier is narrower in the track width direction than in the track length direction of the magnetic recording medium, the track is formed on the ferromagnetic material constituting the convex portion. Shape anisotropy occurs in the width direction, and the track width direction tends to be an easy axis of magnetization. Therefore, the residual magnetization generated by direct current saturation of the ferromagnetic material in the track length direction is small, and a sufficient recording magnetic field of the track length direction component cannot be obtained. In addition, a high coercive force material having hard magnetism generally has difficulty in controlling magnetic anisotropy, and induces anisotropy in the track length direction that can compensate for the bit shape contribution as described above. Is also difficult.

When the ferromagnetic material constituting the convex portion of the master information carrier is made of a soft magnetic material or a hard or semi-hard magnetic material having a relatively low coercive force,
This is preferable because the above problem can be solved relatively easily. Since the distinction between a hard magnetic material and a semi-hard magnetic material is ambiguous, hereinafter, in the present application, a hard or semi-hard magnetic material having a relatively low coercive force will be collectively used as a semi-hard magnetic material. .

These soft magnetic materials and semi-hard magnetic materials have a high coercive force by means of intentionally applying various types of energy during the material forming process or by means of annealing in a magnetic field after the material is formed. Appropriate magnetic anisotropy can be easily induced as compared with a hard magnetic material. Therefore, it is often relatively easy to compensate for the shape anisotropy due to the contribution of the bit shape as described above. Further, among soft magnetic materials or semi-hard magnetic materials, there are abundant materials having a high saturation magnetic flux density suitable as a ferromagnetic material constituting a convex portion of a master information carrier . Examples of the soft magnetic material suitable for the ferromagnetic material constituting the convex portion of the master information carrier of the present invention include, for example, Ni-Fe and F which are generally used as a magnetic head core material.
Crystal material such as e-Al-Si, C such as Co-Zr-Nb
There are o-based amorphous materials and Fe-based microcrystalline materials such as Fe-Ta-N. As a semi-hard magnetic material having a relatively low coercive force, for example, Fe, Co, Fe-Co, or the like is suitable.

In the structure of the present invention, the ferromagnetic material constituting the convex portion needs to be magnetized in one direction in the recording process to generate a recording magnetic field. However, a soft magnetic material or a semi-hard magnetic material originally has In many cases, stable one-way magnetization cannot be obtained in the residual magnetization state. Therefore, in a configuration using a soft magnetic material or a semi-hard magnetic material, in many cases, a DC excitation magnetic field for exciting these and generating an appropriate recording magnetic field is separately applied. As described above, this DC exciting magnetic field can be considered to correspond to the exciting magnetic field supplied by the winding current in the magnetic head.

FIG. 7 shows an example of the configuration of a method for recording a master information signal using the above-described DC exciting magnetic field. FIG. 7 also shows a configuration example of a cross section in the track length direction of the magnetic recording medium, similarly to FIG.

The soft magnetic material or semi-hard magnetic material constituting the convex portion of the master information carrier is magnetized stably in the track length direction of the magnetic recording medium 5 by the DC exciting magnetic field 9 to generate the recording magnetic field 7. Since the DC exciting magnetic field 9 is also applied to the magnetic recording medium 5, it cannot be set to a very large value. In many cases, a size approximately equal to the coercive force of the magnetic recording medium is preferable. If the magnitude of the DC excitation magnetic field 9 is equal to or less than the coercive force of the magnetic recording medium, the recording magnetic field 7 generated from the soft magnetic material or the semi-hard magnetic material forming the convex portion is sufficiently large.
As in the configuration of FIG. 6, a recording magnetization pattern corresponding to the uneven shape can be recorded. In practice, the appropriate magnitude of the DC excitation magnetic field 9 depends on factors such as the magnetic characteristics of the soft magnetic material or semi-hard magnetic material constituting the convex portion of the master information carrier , the magnetic characteristics of the magnetic recording medium, and the shape of the concavo-convex pattern. It changes in various ways. Therefore, it is necessary to experimentally optimize the coercive force value of the magnetic recording medium so that the recording characteristics are most excellent in each case.

From the above point of view, the soft magnetic material and semi-hard magnetic material constituting the convex portion of the master information carrier almost reach the magnetic saturation by the DC exciting magnetic field 9 which is almost equal to the coercive force of the magnetic recording medium. preferable. Soft magnetic materials often exhibit good saturation characteristics at low magnetic fields. However, since some semi-hard magnetic materials require a relatively large saturation magnetic field, attention must be paid to material selection. According to the experimental results of the present inventors, when recording on a hard disk medium having a current general coercive force or a large-capacity flexible disk medium, a semi-hard magnetic material having a coercive force of 500 Oersted or less is used. Is preferred. When the coercive force is larger than 500 Oersted, the DC exciting magnetic field 9 necessary for stably magnetizing the semi-hard magnetic material in the track length direction of the magnetic recording medium 5 becomes larger than the medium coercive force. It becomes difficult to perform recording with excellent resolution.

The recording method for applying a DC excitation magnetic field as shown in FIG. 7 is suitable for a recording method in which the ferromagnetic material constituting the convex portion of the master information carrier is made of a material having a high coercive force, especially an AC bias magnetic field larger than the coercive force. It is effective when giving. As described above, when an AC bias magnetic field larger than the coercive force of the ferromagnetic material is applied in the configuration shown in FIG. 6, the magnetization 6 of the convex ferromagnetic material decreases and a sufficient recording magnetic field 7 is generated. No longer available. At this time, by applying the DC excitation magnetic field in a superimposed manner, the total external magnetic field applied in the opposite polarity to the magnetization 6 of the ferromagnetic material is reduced, and a stable recording magnetic field is provided in the same manner as when no AC bias magnetic field is applied. Can occur. As described above, the configuration in which the AC bias magnetic field and the DC excitation magnetic field that attenuate with time are superimposed and applied is applicable even when the ferromagnetic material forming the master information carrier convex portion is made of a semi-hard magnetic material or a soft magnetic material. Of course, it is effective.

Depending on the uneven pattern on the surface of the master information carrier , as shown in FIG. 8, better recording can be achieved by performing DC saturation erasure of the magnetic recording medium in advance and giving initial magnetization 10 in one direction. May be possible.

The concavo-convex pattern has various forms according to the information signal required for each application. For this reason, depending on the concavo-convex pattern, one of the recording magnetic field on the convex surface and the recording magnetic field on the concave surface is smaller than the other, and it is difficult to achieve a sufficient saturation recording with the smaller polarity, or the recording linearity A phenomenon such as spoiling is caused. In the configuration shown in FIG. 8, the DC recording and erasing of the magnetic recording medium 5 is performed in advance so that the magnetic recording medium 5 has the same polarity as the smaller one of the recording magnetic field on the convex surface and the recording magnetic field on the concave surface. , The saturation recording in the same polarity direction can be assisted.

FIG. 8 shows an example in which the magnetic recording medium 5 is DC-saturated and erased to have the same polarity as the recording magnetic field on the surface of the convex portion. It should be noted that the polarity differs in each case. FIG. 8 shows the case where the DC excitation magnetic field 9 is applied as in FIG. 7. However, even when the DC excitation magnetic field 9 is not applied, the effect of DC saturation elimination can be obtained similarly.

In the above, the case of recording on the longitudinal magnetic recording medium has been mainly described. On the other hand, the configuration of the recording method of the present invention can be variously changed depending on the type of the magnetic recording medium, and the effects of the present invention can be obtained in the same manner as described above.

As a typical example, the configuration of the recording method of the present invention when the magnetic recording medium is a perpendicular magnetic recording medium is shown in FIG.
Shown in FIG. 9 shows (a) a method of recording a master information signal on a perpendicular magnetic recording medium using a master information carrier ;
(B) a recording magnetization pattern recorded on a perpendicular magnetic recording medium; and (c) a recording resistance pattern (MR)
FIG. 5 shows an example of a signal waveform at the time of reproduction using a head. FIG. FIGS. 6A and 6B show examples of the cross-sectional configuration of the magnetic recording medium in the track length direction, similarly to FIGS.

When recording is performed on a perpendicular magnetic recording medium, as shown in FIG. 3A, the ferromagnetic material forming the convex portion of the master information carrier 4 is provided in a perpendicular direction perpendicular to the surface of the magnetic recording medium 5. The magnetization 6 is given. Therefore, for example, when the ferromagnetic material forming the protrusion is a ferromagnetic thin film,
In order to reduce the demagnetizing field in the vertical direction, it is preferable to make the thickness of the ferromagnetic thin film sufficiently large.

Also, when the DC excitation current 9 is applied, unlike the case where recording is performed on the longitudinal magnetic recording medium, it is applied in the direction perpendicular to the surface of the magnetic recording medium 5. Further, when the magnetic recording medium 5 is subjected to DC saturation erasing in advance and the initial magnetization 10 in one direction is given, DC saturation erasing is performed in the vertical direction, and the initial magnetization 10 in the vertical direction remains. .

The configuration of the present invention can be applied to various magnetic recording media in addition to the above. For example, in the above embodiment of the present invention, the description has been made mainly with a focus on a magnetic disk medium, but the present invention is not limited to this.
The present invention can be applied to a magnetic recording medium such as a magnetic card and a magnetic tape, and the effects of the invention can be obtained in the same manner as described above.

The information signals recorded on the magnetic recording medium have been described with a focus on preformat signals such as a tracking servo signal, an address information signal, and a reproduction clock signal. The applicable information signal 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 master information carrier of the present invention and a method of recording on a magnetic recording medium using the master information carrier enable mass production of a soft disk medium to be produced and can be provided at low cost.

It goes without saying that the various application forms of the present invention as described above, together with various configuration forms modified according to their characteristics, belong to the scope of the present invention.

[0077]

According to the present invention, a servo signal for tracking can be recorded on a magnetic recording medium, particularly a fixed hard disk medium, a removable hard disk medium, or a disk-shaped medium such as a large-capacity flexible medium, in a short time with good productivity and at low cost. And preformat recording of an address information signal, a reproduction clock signal, and the like.

Further, according to the recording method of the present invention, it is possible to perform high-accuracy tracking in a higher track density region than the conventional method.

It should be noted that the present invention does not sacrifice any other important performance such as the magnetic recording medium SN and the head-medium interface performance in order to realize the above-mentioned effects. , Can provide a truly effective solution. That is, the present invention is an effective technique in the field of a magnetic recording / reproducing apparatus to achieve a surface recording density of the future gigabit order or more.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a master information carrier surface of the present invention.

FIG. 2 is a cross-sectional view of the master information carrier of the present invention in the track length direction.

FIG. 3 is a sectional view of the master information carrier of the present invention in the track length direction.

FIG. 4 is a cross-sectional view of a master information carrier of the present invention in a track length direction.

FIG. 5 is a sectional view of the master information carrier of the present invention in the track length direction.

FIG. 6A is a diagram illustrating a method for recording a master information signal on a magnetic recording medium using the master information carrier of the present invention. FIG. 6B is a schematic diagram of a recording magnetization pattern recorded on the magnetic recording medium. Head playback waveform diagram from recorded magnetization pattern recorded on recording medium

FIG. 7 is an explanatory diagram of a method for recording a master information signal on a magnetic recording medium using the master information carrier of the present invention.

FIG. 8 is an explanatory diagram of a method for recording a master information signal on a magnetic recording medium using the master information carrier of the present invention.

9A is a diagram illustrating a method for recording a master information signal on a magnetic recording medium using the master information carrier of the present invention. FIG. 9B is a schematic diagram of a recording magnetization pattern recorded on the magnetic recording medium. Head playback waveform diagram from recorded magnetization pattern recorded on recording medium

[Explanation of symbols]

First magnetization of the ferromagnetic material constituting the convex portions of the master information carrier of the base body 2 ferromagnetic thin film 3 master information carrier made of a ferromagnetic material substrate 4 master information carrier 5 the magnetic recording medium 6 master information carrier 7 the recording magnetic field 8 magnetic recording Recording magnetization of medium 9 DC excitation magnetic field 10 Initial magnetization of magnetic recording medium

──────────────────────────────────────────────────の Continued on front page (72) Inventor Kazuya Yoshimoto 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Keizo Miyata 1006 Kazama Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial In-company (56) References JP-A-57-24032 (JP, A) JP-A-50-60212 (JP, A) JP-A-48-53704 (JP, A) JP-A-39-20762 (JP, A) JP-A-57-109134 (JP, A) JP-A-7-78337 (JP, A) JP-A-5-81671 (JP, A) JP-A-4-251440 (JP, A) International publication 81/165 (WO, A1) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G11B 5/62-5/86 G11B 5/596

Claims (9)

(57) [Claims] A magnetic pattern is recorded on a magnetic recording medium.
A master information carrier for forming a concavo-convex shape corresponding to an information signal on a surface of the master information carrier ;
A master information carrier comprising a ferromagnetic thin film having a thickness of 0.1 μm to 1 μm . 2. The method according to claim 1, wherein the information signal is a tracking servo.
Signal, address information signal, or recovered clock signal
Information signal containing at least one of them
The master information carrier according to claim 1, wherein: 3. The master information carrier according to claim 1, wherein the base is made of a flexible sheet-shaped or disk-shaped substrate. 4. The master information carrier according to claim 1, wherein the ferromagnetic thin film forming the surface of the convex portion of the base is a soft magnetic thin film . 5. An uneven shape corresponding to an information signal is formed on a surface of a substrate, and a film is formed on at least a surface of the convex portion of the uneven shape.
The surface of the master information carrier on which the ferromagnetic thin film having a thickness of 0.1 μm to 1 μm has been formed, the surface of the sheet-like or disk-shaped magnetic recording medium on which the ferromagnetic thin film or the ferromagnetic powder coating layer is formed. A method for manufacturing a magnetic recording medium , comprising: recording a magnetization pattern corresponding to the concavo-convex shape on the magnetic recording medium by contacting the magnetic recording medium. 6. The method for manufacturing a magnetic recording medium according to claim 5 , wherein an AC bias magnetic field is applied in said recording process . 7. The method for manufacturing a magnetic recording medium according to claim 5 , wherein in the recording step, a DC magnetic field for exciting a ferromagnetic material forming the surface of the convex portion of the master information carrier is applied. . 8. The recording process according to claim, characterized in that applying an alternating bias magnetic field, and applying a DC magnetic field for exciting the ferromagnetic material forming the surface of the protrusion of the master information carrier 5 How to manufacture the described magnetic recording medium
Law . 9. The method of claim 5, wherein the prior master information carrier surface is brought into contact with the magnetic recording medium surface, advance DC magnetic field erases the magnetic recording medium
9. The method for manufacturing a magnetic recording medium according to any one of items 1 to 8 .