JPH10149539A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a portable, large-capacity and high-speed magnetic disk device by providing an irregular part for recording information, a soft magnetic layer and a perpendicular magnetic recording layer and reproducing the information by a single magnetic pole type magnetic head. SOLUTION: Information of a hard disk 11 housed in a changeable cartridge 16 is reproduced by this hard disk device 10 using single magnetic pole type magnetic heads 13. The irregular part, the soft magnetic layer and the perpendicular magnetic recording layer are formed for the purpose of recording information on a magnetic substrate of the hard disk 11. Consequently, since the hard disk 11 is housed in the cartridge 16, the device is made portable, and since the irregular part for recording information is provided on the nonmagnetic substrate of the hard disk 11, the information can speedily be written. Also, the recording magnetization is stabilized and the magnetic transition is made steep by providing the perpendicular magnetic recording layer on the nonmagnetic substrate of the hard disk 11, so that the information can be written with high density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive for recording and reproducing information on a magnetic disk.

[0002]

2. Description of the Related Art As a magnetic disk device as an information recording device of a computer, there is, for example, a hard disk device. The hard disk used in the hard disk device includes a fixed hard disk that is fixed in the device and cannot be taken out of the device, and a removable hard disk that can be taken out of the device. Removable hard disks have the advantage of being more portable than fixed hard disks, and have the advantage of larger capacity than floppy disks.Hard disk drives using removable hard disks have a higher capacity than magneto-optical disks. And has the advantage that the reading speed is high.

[0003]

However, with the recent increase in the amount of data, a high-speed hard disk drive using an even larger-capacity removable hard disk has been demanded. Conventional removable hard disks have a flat surface, so-called flat type.
A magnetic recording method in a hard disk device using the magnetic recording method is mainly a method of performing magnetic recording by providing an axis of easy magnetization in a plane of a hard disk, that is, a so-called longitudinal magnetic recording method.

However, in the flat type longitudinal magnetic recording system, the higher the recording density, the more the axial magnetization directions are arranged so as to repel each other. There is a disadvantage that it is difficult to achieve such a large capacity. Further, in a pattern in which the magnetization reversal of the axis is repeated twice, as the interval between the respective magnetization reversals becomes narrower, that is, as the density becomes higher, a peak shift occurs due to magnetization repulsion and waveform interference, and the error rate deteriorates. And the like.

In view of the above, it is an object of the present invention to provide a portable, large-capacity, high-speed magnetic disk drive.

[0006]

According to the present invention, there is provided a magnetic disk drive for reproducing information of a magnetic disk stored in a replaceable cartridge using a single-pole type magnetic head. This is achieved by forming an uneven portion for recording information, a soft magnetic layer, and a perpendicular magnetic recording layer on a non-magnetic substrate of the magnetic disk.

According to the above configuration, since the magnetic disk is housed in the cartridge, the magnetic disk is portable, and the uneven portion for recording information is provided on the non-magnetic substrate of the magnetic disk. Since the speed is increased and the perpendicular magnetic recording layer is provided on the non-magnetic substrate of the magnetic disk, the density of information writing is increased.

[0008]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. It is not limited to these forms unless otherwise stated.

FIG. 1 is a sectional side view showing an example of a hard disk drive which is an embodiment of the magnetic disk drive of the present invention. The hard disk drive 10 includes a spindle motor 12 for controlling the rotation of a hard disk 11 as a recording medium for recording information, and a magnetic head mounted on a pair of sliders for controlling the recording and reproduction of information on both sides of the hard disk 11. 13 is housed in a drive case 14. And spindle motor 1
A control / signal processing circuit 15 for controlling the magnetic head 13 and exchanging information with a computer or the like is mounted on the drive case 14.

The hard disk 11 is housed in a cartridge 16 and is detachable through a drive opening 14 a of a drive case 14. Since the hard disk 11 and the like are housed in the drive case 14 in this manner, the hard disk 11 and the like can be operated in an environment where dust is eliminated. Further, since the hard disk 11 is housed in the cartridge 16 and is detachable from the drive case 14, the hard disk 11 can be replaced or carried. The drive shutter 14b closing the drive opening 14a is opened only when the cartridge 16 is attached to or detached from the drive case 14, so that the confidentiality inside the drive case 14 is maintained in a normal state.

FIG. 2 is an exploded perspective view showing an example of the appearance of the cartridge 16 in which the hard disk 11 is stored. Cartridge part 16 constituting this cartridge 16
a, 16b, the magnetic head 13
Openings 16c and 16d for contacting the cartridge, respectively.
b, a spindle motor opening 16e for the spindle motor 12 to hold the hard disk 11 is provided.

The hard disk 11 is provided with a chucking component 11a serving as a joint with the spindle motor 12. The chucking component 11a is usually mechanically joined to the spindle motor 12, and has a joining force sufficient to rotationally drive the hard disk 11, while providing a mechanism that can be easily separated when detaching. ing. Note that, instead of mechanical joining, joining by permanent magnets may be used.

A cartridge shutter 16f is slidably fitted into the access openings 16c and 16d after the cartridge portions 16a and 16b are attached to each other. When the cartridge 16 is outside the drive case 14, the cartridge shutter 16f
As shown in FIG. 3A, the access openings 16c, 1c
6d is closed so that cartridge 1
6 is mounted in the drive case 14, FIG.
As shown in (B), access openings 16c, 16d
It slides to expose the.
The mechanism for sliding the cartridge shutter 16f is provided in the drive case 14.

FIG. 4 is a plan view showing a detailed example of the hard disk 11 and a sectional side view of a part thereof. As described in the prior art, the longitudinal magnetic recording system of the flat type has a limit in increasing the capacity.
Employs a type in which an uneven portion is provided on the surface in advance, a so-called discrete type, and a method in which magnetic recording is performed by giving an easy axis of magnetization in a direction perpendicular to the film surface, a so-called perpendicular magnetic recording method. . By adopting the discrete type perpendicular magnetic recording system, the demagnetizing effect is extremely small as compared with the flat type longitudinal magnetic recording system, and it is possible to dramatically increase the recording density.

The hard disk 111 comprises a plastic non-magnetic substrate 111c having a magnetic layer 111b having perpendicular magnetic recording characteristics adhered to both surfaces thereof by a sputtering method. A chucking component 111a having a thermal expansion coefficient equivalent to that of the material is bonded. The magnetic layer 111b is made of at least three layers of materials having different functions. For example, in order from the surface of the non-magnetic substrate 111c, a soft magnetic layer (backing layer) 1 made of a high-permeability magnetic material such as permalloy.
11 ba, a recording layer 111 bb made of a magnetic material for perpendicular magnetic recording media such as Co—Cr and a protective layer 111 bc made of a hard non-magnetic material such as carbon are laminated.

On both surface portions of the hard disk 111, a data information writing area 111d for recording data information, a servo information area 111e in which servo information for positioning the magnetic head 13 is recorded in advance, and other areas are provided for each application. Has been split. These areas correspond to the magnetic head 13
Are arranged so as to alternately scan the data information writing area 111d and the servo information area 111e when scanning in the circumferential direction of the hard disk 111 to record and reproduce information. The servo information area 111e has irregularities corresponding to the servo information used for positioning the magnetic head 13, and the data information writing area 111d has irregularities corresponding to the data information. These irregularities are formed collectively as a surface portion of the nonmagnetic substrate 111c when the nonmagnetic substrate 111c is injection-molded, and are formed in a transferred form even after the magnetic layer 111b is applied. ing. Such a hard disk 1
Reference numeral 11 can be configured as a read-only ROM, a readable / writable RAM, or a RAM disk in which a part of the ROM is partially formed.

FIG. 5A is a plan view showing an example of a single-pole type magnetic head which is a detailed example of the magnetic head 13. The single-pole type magnetic head 131 uses the magnetic layer 1 during recording.
11b to generate a magnetic field to be applied to the magnetic layer 1 during reproduction.
A coil 131a for detecting a magnetic flux from the magnetic layer 11b, a main magnetic pole 131b serving as a magnetic flux inflow / outflow path between the coil 131a and the magnetic layer 111b, and a main magnetic pole 131b through a backing layer 111ba in the magnetic layer 111b. And an auxiliary magnetic pole 131c for forming a closed magnetic circuit including the coil 131a.

The formation of the closed magnetic path by the auxiliary magnetic pole 131c increases the efficiency of the magnetic flux between the main magnetic pole 131b and the magnetic layer 111b, so that information can be recorded and reproduced with high density. Since the sectional area of the auxiliary magnetic pole 131c is sufficiently large with respect to the main magnetic pole 131b,
The magnetic flux density flowing between c and the magnetic layer 111b is sufficiently smaller than that of the main magnetic pole 131b, and the auxiliary magnetic pole 131c does not generate a magnetic field that affects the recorded magnetic layer 111b (for example, J.P. Lazza
ri, M .; A. See Torfeh, and J.M. P. Tua
1, IEEE Trans. Magn. , MAG-17,
no. 6 (Nov. 1981) 3120-3121).

FIG. 5B is a plan view showing another example of the single pole type magnetic head. This single pole type magnetic head 13
2 has the same basic configuration as the single-pole type magnetic head 131, but divides the main pole 131b in the middle, and changes the magnetic flux from the magnetic layer 111b by the magnetoresistive effect element 132a arranged at the divided portion. It is different in that information is reproduced by detection (for example, H. Mitsuhashi,
O. Morita, K .; Oniki, S .; Terad
a, A. Matsuzono, and H .; Taken
o, J. et al. of The Magnetic Society
tyof Japan, Vol 18, No. S1 (1
994) 421-424).

The information recording method in the hard disk device 10 having the hard disk 111 and the single-pole type magnetic head 131 described above is a method in which an uneven shape corresponding to the information is formed on the surface of the nonmagnetic substrate 111c. According to this method, information can be collectively and inexpensively recorded at the time of manufacturing the hard disk 111. However, since information is read-only, read-only information such as positioning information of the single-pole magnetic head 131, that is, servo information, Information area 11
All the servo information in 1e is written by this method. In the case of a ROM, the data information of the entire data information writing area 111d is recorded in this manner, and in the case of a RAM in which a part of the ROM is formed, a part of the data information writing area 111d is recorded. Information is recorded in this manner.

FIGS. 6A and 6B are diagrams conceptually showing the above method, wherein FIG. 6A is a sectional side view and FIG. 6B is a plan view. The arrow shown in the figure indicates the direction in which the magnetization in the magnetic layer 111b is oriented. The concavo-convex shape formed on the non-magnetic substrate 111c cannot be converted into an electric signal by the single-pole type magnetic head 131 as it is, but the magnetic layer 111 adhered to the surface of the convex portion of the non-magnetic substrate 111c.
b, ie, the magnetic layer protrusion 111bd, the non-magnetic substrate 111c
The magnetic layer 111b attached to the surface of the concave portion, that is, the magnetic layer concave portion 111be is magnetized in an anti-parallel manner to enable reproduction. Magnetic layer protrusion 11bd and magnetic layer recess 1
The method of magnetizing 1be in an anti-parallel manner is performed by, for example, scanning a single-pole type magnetic head 131 or a permanent magnet on the hard disk 111 without performing high-precision positioning (see JP-A-7-153047). .

The hard disk 111 according to the above-described method is used.
Is read out by the coil 131a of the single-pole magnetic head 131 according to the reproduction principle of a general magnetic recording method. That is, by detecting induced electromotive force generated at both ends of the coil 131a due to a change in magnetic flux from the surface of the magnetic layer 111b, the recorded signal is converted into an electric signal and reproduced. Also, as mentioned above,
The single-pole magnetic head 131 used may be a single-pole magnetic head 132 of a magnetoresistive effect type. At this time,
Since the electric resistance of the magnetoresistive element 132a changes according to the change in the received magnetic field, information can be read as an electric signal by measuring the resistance of the magnetoresistive element 132a.

FIG. 7 is a plan view showing another detailed example of the hard disk 11 and a sectional side view of a part thereof. This hard disk 112 is made of a plastic non-magnetic substrate 112c having a magnetic layer 112b having perpendicular magnetic recording characteristics adhered to both surfaces by a sputtering method, and the central portion thereof is equivalent to the plastic material of the non-magnetic substrate 112c. The chucking component 112a having a thermal expansion coefficient of?

On both surface portions of the hard disk 112, a data information writing area 112d for recording data information, a servo information area 112e in which servo information for positioning the magnetic head 13 is recorded in advance, and other areas are provided for each application. Has been split. These areas correspond to the magnetic head 13
Are arranged so as to alternately scan the data information writing area 112d and the servo information area 112e when scanning in the circumferential direction of the hard disk 112 to record and reproduce information. The servo information area 112e has irregularities corresponding to the servo information used for positioning the magnetic head 13, and the data information writing area 112d has irregularities corresponding to the data information. These irregularities are formed collectively as a surface portion of the nonmagnetic substrate 112c when the nonmagnetic substrate 112c is injection-molded, and are formed in a transferred form even after the magnetic material layer 112b is applied. ing. Such a hard disk 1
Reference numeral 11 can be configured as a read-only ROM, a readable / writable RAM, or a RAM disk in which a part of the ROM is partially formed.

FIG. 8 is a plan view showing an example of a ring-type magnetic head which is a detailed example of the magnetic head 13. The ring-type magnetic head 133 includes a reproducing unit 133a that magnetically reads information on the hard disk 112, and a recording unit 133b that magnetically writes information on the hard disk 112. The reproducing unit 133a includes a read element 133c including a magnetoresistive element whose electric resistance changes according to a magnetic field. The recording unit 133b includes a coil 133d for generating a magnetic field, a core 133e made of a soft magnetic material for guiding the magnetic field, and a gap 133f for dispersing the magnetic field in the core 133e to the outside.

In addition, not only the ring-type magnetic head 133 but also a recording portion is provided, and the coil 133d is changed by a change in a magnetic field flowing from the magnetic layer 112b into the gap 133f.
Hard disk 11 by induced electromotive force generated at both ends of
A ring type magnetic head integrated with a recording / reproducing unit for reproducing the information on the second unit may be used.

The information recording method in the hard disk device 10 including the hard disk 112 and the single-pole type magnetic head 133 described above is a method in which an uneven shape corresponding to the information is formed on the surface of the nonmagnetic substrate 112c. According to this method, information can be collectively and inexpensively recorded at the time of manufacturing the hard disk 112. However, since information is read-only, read-only information such as positioning information of the ring-type magnetic head 133, ie, servo information Area 11
All the servo information in 2e is written by this method. In the case of a ROM, the data information of the entire data information writing area 112d is recorded by this method, and in the case of a RAM in which a part of the ROM is formed, a part of the data information writing area 112d is recorded. Information is recorded in this manner.

FIGS. 9A and 9B are diagrams conceptually showing the above method, wherein FIG. 9A is a sectional side view and FIG. 9B is a plan view. The arrow shown in the figure indicates the direction in which the magnetization in the magnetic layer 112b is oriented. The concavo-convex shape formed on the non-magnetic substrate 112c cannot be converted into an electric signal by the ring-type magnetic head 133 as it is, but the magnetic material layer 112 adhered to the surface of the convex portion of the non-magnetic substrate 112c.
b, ie, the magnetic layer convex portion 112bd, the nonmagnetic substrate 112c
The magnetic layer 112b attached to the surface of the concave portion, that is, the magnetic layer concave portion 112be is magnetized in an anti-parallel manner to enable reproduction. As a method of magnetizing the magnetic layer convex portions 112bd and the magnetic layer concave portions 112be in an anti-parallel manner, for example, the ring type magnetic head 133 or the permanent magnet is scanned on the hard disk 112 without performing high-precision positioning. (See JP-A-7-153047).

The hard disk 112 according to the above-described method
Is read out by the read element 133c of the ring-type magnetic head 133 according to the reproduction principle of a general magnetic recording method. That is, the recorded signal is reproduced by converting a magnetic field change near the surface of the magnetic layer 112b into an electric signal. At this time, the read element 1
33c is a read element 13 according to a change in the received magnetic field.
Since the electric resistance value of 3c itself changes, the read element 1
By measuring the resistance value of 33c, information can be read as an electric signal. Further, as described above, the ring-type magnetic head 133 used may be a ring-type magnetic head integrated with the recording / reproducing unit, and in this case, the coil 133d is changed by a change in the magnetic field flowing into the core 133e.
The information is read out as the induced electromotive force generated inside.

Here, in the case of the above-described hard disk 112, by making the magnetic layer 112b a perpendicular magnetization film, the groove depth of the magnetic layer concave portion 112be required for magnetization by the ring-type magnetic head 133 is reduced. It can be made shallow, which results in flying stability of the ring-type magnetic head 133. Because the ring type magnetic head 13
When the two-stage magnetization is performed by using the magnetic material layer convex portion 112,
bd (hereinafter referred to as the upper layer) and the magnetic layer recess 112be
After the upper layer is magnetized in one direction (hereinafter referred to as the lower layer), only the upper layer is magnetized in the opposite direction. At this time, an appropriate groove depth is set so that the lower layer is not inverted by a head magnetic field that magnetizes the upper layer. A height difference between them is necessary.

As shown in FIGS. 10A and 10B, when a magnetic field of H (d) is applied to the upper layer, H (d) is also applied to the lower layer.
The (d + h) magnetic field is inevitably applied. Therefore,
The height difference h for preventing the lower layer from being inverted can be reduced as the upper and lower layer magnetic field ratio R represented by the formula (1) is smaller.

(Equation 1) Here, d is the spacing (ring type magnetic head 133).
And h is the height difference between the upper and lower layers (the groove depth of the magnetic layer recess 112be).

Therefore, with respect to the in-plane component and the perpendicular component of the magnetic field of the ring-type magnetic head 133, the expression giving the expression (1) is derived using the approximate expression of Karlkvist, that is, the expression indicating the magnetic field distribution of the ring-type magnetic head 133. I will try. First, the magnetic field Hx (x, y) of the in-plane component is given by Expression (2).

(Equation 2) Here, Hg is the magnetic field in the gap, and g is the gap length.

The applied magnetic field when the magnetic layer 112b is magnetized can be determined by considering the value when the magnetic field Hx (x, y) of the in-plane component reaches the maximum. . In other words, the upper and lower layer magnetic field ratio R of the in-plane component is given by equation (4).

(Equation 3)

(Equation 4) Next, the magnetic field Hy (x, y) of the vertical component is given by Expression (5).

(Equation 5)

The magnetic field applied when the magnetic layer 112b is magnetized may be determined by considering the value when the magnetic field Hy (x, y) of the vertical component reaches the maximum, and therefore, equation (6) may be considered. That is, the upper and lower layer magnetic field ratio R of the vertical component is represented by the following equation (7).

(Equation 6)

(Equation 7)

The values of the spacing d and the gap length g actually used are as follows: d is 10 nm or 50 nm, and g is 20
Since it is 0 nm or 400 nm, these values are substituted into Expressions (4) and (7) and plotted against the height difference h between the upper layer and the lower layer, as shown in FIGS. That is, the upper and lower layer magnetic field ratio R of the in-plane component is always larger than the upper and lower layer magnetic field ratio R of the vertical component. That is, when a perpendicular magnetization film magnetized by the perpendicular component of the head magnetic field is used, the height difference h between the upper layer and the lower layer, which is smaller than the in-plane magnetization film, that is, the same upper and lower layer magnetic field ratio R can be obtained even in a shallow groove. To be
Magnetization is possible even in shallow grooves.

FIG. 14 is a conceptual diagram showing the most common use example of the hard disk device 10. As shown in FIG. The hard disk device 10 is connected to a device that processes information such as a computer 20 through a control / signal processing circuit 15 and a DC power supply 30 that receives supply of power required for operation. When the control / signal processing circuit 15 receives information and a command for recording the information from the computer 20, the control / signal processing circuit 15 drives the magnetic head 13 to write information on the hard disk 11. When receiving a command to reproduce, the magnetic head 13 is similarly driven to reproduce the designated information from the hard disk 11 and sends it to the computer 20. Hard disk 11
Is stored in the cartridge 16 and the hard disk drive 1
It can be easily attached and detached from zero, can be stored and transported in a state where information is recorded, and can be replaced with a new hard disk 11 when the recording capacity is full.

As described above, since the magnetic disk device of this embodiment has a mechanism in which the hard disk can be detached, it is possible to exchange, transport, and store the information on the hard disk alone. Further, since a perpendicular magnetic recording system is used in which information is recorded in units of a perpendicular magnetic recording layer magnetized in a direction perpendicular to a non-magnetic substrate, a magnetic disk device of a longitudinal magnetic recording system widely used at present. As compared with the above, the recording magnetization is stable and the magnetization transition is sharp, and information can be recorded and reproduced at a high linear recording density.

When a non-magnetic substrate material such as plastic is injection-molded, a hard disk is used in which read-only information such as magnetic head positioning information is collectively formed as irregularities on the non-magnetic substrate. It can be mass-produced. Furthermore, since these irregularities are formed by a mastering method used in the manufacture of optical disks, generally, the track densities are sufficient to realize a track density equivalent to an optical disk having a higher track density than a magnetic disk. Since the read-only information is recorded with high precision, it is possible to record and reproduce information at a higher track density than in the past.

[0039]

As described above, according to the present invention,
Since the magnetic disk is housed in the cartridge, portability can be provided. In addition, since the uneven portion for recording information is provided on the non-magnetic substrate of the magnetic disk,
Writing of information can be speeded up. Further, since the perpendicular magnetic recording layer is provided on the non-magnetic substrate of the magnetic disk, the density of information writing can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional side view showing an example of a hard disk drive which is an embodiment of a magnetic disk drive according to the present invention.

FIG. 2 is an exploded perspective view showing an example of an appearance of a cartridge in which the hard disk of FIG. 1 is stored.

FIG. 3 is a perspective view showing an example of the appearance of the cartridge shown in FIG. 2;

FIG. 4 is a plan view showing a detailed example of the hard disk of FIG. 1 and a sectional side view of a part thereof.

FIG. 5 is a plan view showing an example of a single-pole type magnetic head which is a detailed example of the magnetic head of FIG. 1;

FIG. 6 is a sectional side view and a plan view conceptually showing an information recording method using the magnetic head of FIG. 5;

FIG. 7 is a plan view showing another detailed example of the hard disk of FIG. 1 and a sectional side view of a part thereof.

FIG. 8 is a plan view showing an example of a ring-type magnetic head which is a detailed example of the magnetic head of FIG. 1;

9 is a sectional side view and a plan view conceptually showing an information recording method using the magnetic head of FIG. 8;

FIG. 10 is a side view for explaining an information recording method using the magnetic head of FIG. 8;

FIG. 11 is a first diagram showing information recording characteristics of the magnetic head of FIG. 8;

FIG. 12 is a second diagram illustrating information recording characteristics of the magnetic head of FIG. 8;

FIG. 13 is a third diagram showing information recording characteristics of the magnetic head of FIG. 8;

FIG. 14 is a conceptual diagram showing the most common use example of the hard disk device of FIG.

[Explanation of symbols]

10 ... Hard disk device, 11, 111, 112
... Hard disks, 11a, 111a, 112a
..Chucking parts, 111b, 112b ... magnetic layer, 111c, 112c ... non-magnetic substrate, 111
d, 112d... data information writing area, 111e, 1
12e: servo information area, 111ba, 112ba
... Backing layer, 111bb, 112bb ... Recording layer, 111bc, 112bc ... Protective layer, 12 ...
Spindle motor, 13, 131, 132 ... magnetic head, 131a, 133d ... coil, 131b ...
· Main magnetic pole, 131c ··· Auxiliary magnetic pole, 132a ··· Magnetoresistance effect element, 133a ··· Reproduction section, 133b ···
. A recording unit, 133c ... readout element, 133e ...
Core, 133f gap, 14 drive case, 14a drive opening, 14b drive shutter, 15 control / signal processing circuit, 16
... Cartridge, 16a, 16b ... Cartridge part, 16c, 16d ... Access opening, 16
e: spindle motor opening, 16f: cartridge shutter, 20: computer, 30 ...
・ DC power supply

Claims (4)

[Claims] 1. A magnetic disk drive for reproducing information from a magnetic disk stored in an exchangeable cartridge using a single-pole type magnetic head, comprising: a non-magnetic substrate for recording information on a non-magnetic substrate of the magnetic disk; A magnetic disk device comprising an uneven portion, a soft magnetic layer, and a perpendicular magnetic recording layer. 2. The magnetic disk drive according to claim 1, wherein the information on the magnetic disk can be recorded and reproduced by using the single-pole type magnetic head. 3. A magnetic disk drive for reproducing information on a magnetic disk stored in a replaceable cartridge using a ring-type magnetic head, comprising: a concave and a convex for recording information on a non-magnetic substrate of the magnetic disk. And a perpendicular magnetic recording layer. 4. The magnetic disk drive according to claim 3, wherein information on the magnetic disk can be recorded and reproduced using the ring-type magnetic head.