JPH0319101A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To improve recording density and to obtain a small and mass storage magnetic disk device by specifying the interval of the magnetic head and the magnetic disk, the saturation magnetic flux density of the tip part of a magnetic pole in the magnetic head and the coercive force of the magnetic recording medium of the magnetic disk. CONSTITUTION:The ring type thin film magnetic head 2 of high saturation magnetic flux density and the magnetic recording medium 3 of high coercive force are provided, and the medium 3 is formed as the magnetic disk. Then, one or plural disks are connected by a single spindle and they rotate. At least 0.1mum is secured for the interval of the medium 3 and the magnetic head 2 and reliability is guaranteed. The magnetic head 2 is one whose saturation magnetic density of the tip part of the magnetic pole is more than 12kG and the recording medium 3 is the application type medium where a cirular particles are applied and it is the this film medium whose coercive force is more than about 7000e. Thus, the magnetization of the recording medium 3 can efficiently be detected at the time of reproduction, the recording density of the device 1 can considerably be improved and the mass storage device 1 in the same floor space can be obtained.

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to a magnetic disk device. In particular, it relates to small-sized, large-capacity magnetic disk drives.

[Conventional technology 1] A conventional large fixed magnetic disk device has a coercive force of 400
Recording and reproduction have been performed using a combination of a coated medium with a magnetic flux density of about 0.0 e and a ferrite bulk head with a saturation magnetic flux density of about 5 kG. Recently, thin-film heads using permalloy as a magnetic pole material with a saturation magnetic flux density of 10 kGf4 degrees have been used as magnetic heads. In combination, it is not possible to increase the recording density of a magnetic disk device without impairing reliability. In other words, the areal recording density of currently used magnetic disk devices is 20~
40 Mb/in", but if we try to increase this with the combination of conventional recording media and magnetic heads, the spacing between the head and media will be reduced to the current approximately 0.2 μm.
m, it must be reduced to about 0.1 μm or less. In order to improve recording density without reducing spacing, it is necessary to consider the characteristics of the recording medium and magnetic head used. Examples of attempts to improve the performance of magnetic heads include page 117 of the 7th Japanese Society of Applied Magnetics Academic Lecture Abstracts, Journal of Applied Physics, 63 (198
8) pages 4020 to 4022 (J. Appl.
Phys, 6 3 (8) (1988) pp. 402
There is an example of a thin film magnetic head using a high saturation magnetic flux density material as the magnetic pole, as shown in 0-4022). However, in these examples, only attempts have been made to increase the recording capacity of the magnetic head, and insufficient consideration has been given to obtaining a high recording density as a magnetic disk device. In other words, even if the recording capacity is high, if the playback efficiency is low,
It is not possible to obtain a sufficient S/N ratio to operate the device, and if waveform distortion (wiggle) occurs, errors occur, making it impossible to increase the recording density. Regarding recording media, increasing the coercive force increases the conservation power of signal magnetization. However, if sufficient recording is not possible, the reproduction signal becomes small and noise increases, so it is not necessarily possible to increase the recording density of the device. Therefore, increasing the capabilities of the magnetic head and the recording medium independently does not necessarily improve the recording density of the magnetic disk device. Furthermore, as a method for increasing the S density, a perpendicular magnetic recording system has recently been studied to replace the conventional longitudinal magnetic recording. This is a method of recording and reproducing by combining a so-called perpendicular magnetization medium, which is easily magnetized in the direction perpendicular to the medium surface, and a single-pole magnetic head. It has been experimentally confirmed that this method can record signals on magnetic media at extremely high densities of several hundred kBPI. However, in order to operate as a magnetic disk device, with such high recording density, the S/N is not sufficient as with longitudinal recording, and even when using the perpendicular recording method, the recording density is insufficient with conventional recording media and magnetic heads. It can only be put into practical use at low PPI of several tens of kBPI. [Problems to be Solved by the Invention] The above-mentioned prior art does not give sufficient consideration to improving the recording density of the magnetic disk device. An object of the present invention is to improve the recording density without impairing the reliability of the magnetic disk device, and to realize a compact, large-capacity magnetic disk device.

[Means to solve the problem]

In order to achieve the above objectives, the distance between the medium and the magnetic head must be at least 0.1 μm to ensure reliability, and at the same time, the magnetic head has a saturation magnetic flux density of 12 kG or more at the tip of the magnetic pole and a recording medium with excellent storage power. A disk device with an areal recording density of 50 Mb/in" or higher is created by combining the following.
Recording media that can perform high-density recording and have excellent storage power are coated media coated with acicular fine particles of approximately 700 Oe, and thin film media formed by plating, sputtering, vapor deposition, etc. of approximately 120,000 Oe. is necessary.

[Effect]

According to the present invention, a magnetic head whose magnetic pole is made of a high saturation magnetic flux density material with controlled magnetic properties has a gap of 0.1 μm between the medium and the head.
Even if a spacing of m or more is provided, the high coercive force medium is completely magnetized during recording, and the magnetization of the recording medium is efficiently detected during reproduction, so that the recording density of the magnetic disk device can be greatly improved. Table 1 shows the characteristics of the magnetic pole material used in the magnetic head of the present invention. Table 1 Materials that satisfy the characteristics required for the magnetic head of the present invention include, for example, Co-based amorphous gold and Fe-based crystalline alloy. The saturation magnetic flux density Bs is shown in the table. For comparison, a conventional material, Permalloy (Bs ~ 10 kG), was also used. Co-based amorphous alloys include CoNbZr, CoWZr, CoT
aFe-based crystalline alloys, such as aZr, whose alloy composition is selected so that the magnetostriction constant λS is almost zero, can have improved magnetic permeability by multilayering FeC alloys or FeSi alloys with a NiFe alloy as an intermediate layer. These alloys were also selected so that their magnetostriction constants were approximately zero.
These magnetic pole materials were deposited using RF sputtering.
The thin film head was formed on a substrate using photolithography technology used to fabricate semiconductors such as VLSI, and was fabricated through mechanical processes such as cutting, grinding, and polishing. Since this is a conventionally known method, its explanation will be omitted. Table 2 shows the magnetic recording media used in the present invention. Table 2 Preferable materials for the medium used in the present invention include, for example, Co, γ-FelO3, Fe, B
a Sputtering medium made by coating a substrate with a binder material using a medium containing magnetic powder such as ferrite, CoNi
The coercive force was controlled by changing the sputtering conditions. For comparison, low coercive force media such as γ-Fe20 and coated media conventionally used in magnetic disk drives were also used. The recording medium magnetic disk is rotated at a relative speed of 30 m/s.
The magnetic head was floated at a spacing of 0.2 μm, and the recording and reproducing characteristics were measured. Figure 2 shows the relationship between S/N and recording density for various combinations of recording media and magnetic heads. The recording density on the horizontal axis is the areal recording density [bit/inch"]. The track width Tw of the magnetic head is shown by experimentally selecting a value that increases with the recording density characteristics. The S/N is the reproduction output s [vp -p]
and noise N[vP-P], and the frequency band was up to twice the frequency corresponding to each linear recording density. The amplifier selected has the lowest noise among those currently available, and the noise is 0.3 nV/VHz. Further, the number of turns of the magnetic head coil was 22 turns, and the resistance was about 150, and the head noise was thermal noise caused by this resistance. Conventional technology was used for these amplifiers and heads. If conventional techniques are used for signal discrimination, etc., the S/N that can operate as a magnetic disk device is about 2 or more.
Therefore, with the combination of the conventional head (2) and the recording medium A, the limit is approximately 40 Mb/in" and 50 Mb/in".
Mb/in”).On the other hand,
The combination of the head (1) of the present invention and the recording medium B is approximately 7.
5 M b /in'', head ■ of the present invention and recording medium D
In combination with this, it is possible to operate as a magnetic disk device up to approximately 150 Mb/in2. FIG. 3 shows the coercive force He [Oe] of the recording medium and the output half-loss line recording density D. . This is a graph showing the relationship with [kBPI]. Conventional magnetic head I with a saturation magnetic flux density of ~10kG
When using the coating medium, the coercive force is 70
0 0 e or more, 1200 Oe for sputtering media
Even with the above, D. is not large and is only 35 kBPI at most. Moreover, as the coercive force increases, the operite characteristics worsen, so simply increasing the coercive force does not increase the recording density. On the other hand, when using the magnetic head (2) of the present invention with a saturation magnetic flux density of 12 kG, the
Oe, particularly high D, in the range 1200-1500 Oe for sputtering media. can be obtained, and output efficiency can be improved. In addition, when using the magnetic head (2) of the present invention with a saturation magnetic flux density of 20 kG, the magnetic head
, D, even at over 2400 Oe for the sputtering medium. tends to grow further. Figure 4 is a graph showing the relationship between the saturation magnetic flux density Bs [kG] and the overwrite characteristic [dB] of the magnetic head. The overwrite characteristics are D, in addition to recording a low recording density (1 kBPI) signal. record a signal with a recording density of
This is expressed as the remaining part of the original low recording density signal. When conventional coating medium A with a coercive force of 400 Oe is used and the saturation magnetic flux density of the magnetic head is 10 kG as before, overwriting greatly exceeds the device operating condition of approximately 25 dB. However, when recording medium B of the present invention having a coercive force of 700 Oe is used, the saturation magnetic flux density of the head must be 12 kG or more to enable operation as a disk device. Furthermore, when recording medium D having a coercive force of 1500 Oe is used, it is found that the saturation magnetic flux density is required to be approximately 18 kG or more. [Examples] Examples of the present invention will be described below. As shown in FIG. 1, the magnetic disk drive 1i1 of this embodiment has at least a ring-shaped thin film magnetic head 2 with a high saturation magnetic flux density and a magnetic recording medium 3 with a high coercive force. Magnetic recording medium 3
is formed as a magnetic disk, and one or more disks can be coupled and rotated by a single spindle. The magnetic heads 2 are installed at intervals on each recording surface of the magnetic recording medium. This magnetic head is usually movable in the radial direction of the magnetic disk by actuator means or the like, so that it can be moved between tracks. A recording/reproducing circuit is connected to the magnetic head to perform recording and reproduction. An example of a specific device is shown in FIG. In the embodiment shown in FIG. 6, the magnetic disk device of this embodiment has a plurality of heads 2 on the same recording surface within one magnetic disk device, and three disk surfaces are covered by the same arm 310.
Recording/reproduction is performed using multiple magnetic heads 2 connected to the magnetic head. In Figure 6, four heads are installed. In this embodiment, data sent from the CPU 130 is sent to the controller 14.
0, the recording/reproducing circuit 100 is activated, a head is selected by the head selection switch 320, and information is recorded/reproduced on the medium surface 3. The magnetic head 2 of this embodiment is a thin film magnetic head as shown in US Pat. No. 4,190,872, and performs in-plane recording. The magnetic pole material of this head is the first
These are Co-based amorphous alloys or Fe-based crystalline alloys shown in the table. An alloy set such as CoTaZr was selected so that the magnetostriction constant λS was approximately zero. Fe-based crystalline alloy is FeC
An alloy whose magnetic permeability is improved by multilayering an alloy or FeSi alloy with a NiFe alloy as an intermediate layer,
These were also selected in such a way that the magnetostriction constant was approximately zero. These magnetic pole materials were formed into films by RF sputtering. Thin film heads are formed on a substrate using bottling techniques used to fabricate semiconductors such as VLSI, and then cut, ground, and
It was manufactured through mechanical processes such as polishing. Since this is a conventionally known method, the explanation will be omitted. The coating media and sputtering media shown in Table 2 were used as magnetic recording media. The coating medium is Go-γ-Fe203, Fe, B
The sputtering medium, which was prepared by coating a substrate with a magnetic powder such as a-ferrite together with a binder material, was a CoNi-based alloy, and the coercive force was controlled by changing the sputtering conditions. The recording medium magnetic disk is rotated at a relative speed of 30 m.
/s magnetic head, spacing 0.2 μm
The recording and reproducing characteristics were measured. FIG. 2 shows the relationship between S/N and recording density for various combinations of recording media and magnetic heads. The recording density on the horizontal axis is the areal recording density [bit/in
The track @TV of the magnetic head is shown by experimentally selecting the value that gives the most extended recording density characteristics. S/N is the reproduction output S [Vp-pl and the noise N [Vp-
pl (7) ratio, and the frequency band was up to twice the frequency corresponding to each linear recording density. The recording/playback circuit amplifier was chosen to have the lowest noise among those currently available, but the noise was 0. 3 n V / v'H
It is z. Further, the number of turns of the magnetic head coil was 22 turns, and the resistance was about 15Ω, and the head noise was thermal noise due to this resistance. Conventional technology was used for these amplifiers and heads. In the combination of the head (■) of the present invention and the recording medium B, approximately 75
Mb/in", and the combination of the head (■) of the present invention and the recording medium D has an S/N of 2 or more up to about 150 Mb/in"
It has the potential to operate as a magnetic disk device. FIG. 3 is a graph showing the relationship between the coercive force Hc [Oe] of the recording medium and the output half-loss linear recording density D, [kBPI]. When using the magnetic head (2) of the present invention with a saturation magnetic flux density of 12 kG, if the coercive force of the medium increases beyond a certain level, the result will be D. A high Dsa can be obtained in the range of 700 to 1200 Oe for coating media and 1200 to 1500 Oe for sputtering media. In addition, when using the magnetic head (■) of the present invention with a saturation magnetic flux density of 20 kG, 1 5
0 0 0 e, 2 4 0 for sputtering media
D even if it exceeds 0 0 s. It is clear that the present invention is superior. Figure 4 is a graph showing the relationship between the saturation magnetic flux density Bs [kG] and the overwrite characteristic [dB] of the magnetic head. The overwrite characteristics are D, in addition to recording a low recording density (1 kBPI) signal. record a signal with a recording density of
This is expressed as the remaining part of the original low recording density signal. When recording medium B of the present invention having a coercive force of 700 Oe is used, the saturation magnetic flux density of the head must be 12 kG or more to enable operation as a disk device. Furthermore, when recording medium D with a coercive force of 1500 Oe is used, it is found that the saturation magnetic flux density is required to be approximately 18 kG or more. As shown above, by appropriately combining the saturation magnetic flux density of the head magnetic pole and the coercive force of the medium, it is possible to improve the spacing between the head medium without impairing the sliding reliability of conventional magnetic disk drives. It can be seen that high-density recording is possible without significantly changing the In the past, research has been conducted to increase the coercive force of recording media and the saturation magnetic flux density of the head magnetic pole, but as can be seen from the results of this example, simply increasing the coercive force and saturation magnetic flux density is insufficient. It does not necessarily mean that the operating recording density of a magnetic disk device will be higher. Simply increasing the coercive force does not necessarily increase the recording density. The present invention was made possible for the first time by developing a magnetic head with a high saturation magnetic flux density and a recording medium with a high coercive force and repeatedly conducting prototype evaluations. Note that the performance of a thin-film magnetic head cannot be represented solely by the saturation magnetic flux density material of the magnetic pole material. For example, when trying to obtain high reproduction output, the magnetic anisotropy field of the magnetic pole material is 4 to 15 Oe.
It is necessary to control it within the range of . Figure 5 shows the results (head ■) for a CoTaZr amorphous alloy with a saturation magnetic flux density of 14 kG. Here, the anisotropic magnetic field was controlled by performing heat treatment in a magnetic field and changing the heat treatment temperature, time, and direction of the magnetic field. This is the reproduction output when the recording medium is a coated medium (medium C) with a coercive force of 1200 Oe. Anisotropic magnetic field is 4 to 15 Oe
A high reproduction output can be obtained in the range of 5 to 8 Oe, more preferably in the range of 5 to 8 Oe. Note that it is desirable that the easy magnetization direction be in the track width direction of the head, and if it is tilted significantly from this direction, waveform distortion (wiggle) may occur or the reproduction output may decrease. The magnetostriction constant of the magnetic pole material is also important;
If it deviates from the range of +5×10 −7 , problems such as generation of waveform distortion and reduction in reproduction output will occur. As the magnetic pole material with high saturation magnetic flux density, a Co-based amorphous alloy or a Fe-based crystalline alloy can be used. Co-based amorphous alloys include CoMoZr, CoWZr, CoZrR
e, CoNbZr, CoTaZr, etc. can be used, but the upper limit of the saturation magnetic flux density is about 15 kG. Fe-based crystalline alloys can obtain even higher saturation magnetic flux density, and FeSi, FeC, FeN alloys, etc. can be used. In this case, since it is generally difficult to control the magnetic anisotropy of crystalline alloys, it is desirable to use them as a multilayer structure with other intermediate layer materials interposed therebetween. As the spacing between head media becomes smaller, problems such as head crashes occur. Spacing is 0.1μm
Reliability decreases rapidly after . Furthermore, if the surface roughness of the medium surface is to be reduced to 0.15 μm or less, processing becomes extremely difficult. According to the present invention, approximately 250M at 0.1μm
b/in”, 200 Mb/in at 0.15pm
This is advantageous in practice because it is possible to achieve an areal recording density of "in". [Effects of the Invention] According to the present invention, the areal 11R density of a magnetic disk device can be improved without significantly impairing the conventional sliding reliability. Therefore, a large-capacity device can be obtained with the same floor space.Also, if the current recording density is maintained, the spacing between the head media can be expanded, which can improve reliability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of the present invention, FIGS. 2 to 5 are diagrams each showing the effects of the present invention, and FIG. 6 is a block diagram showing an embodiment of the present invention. No./Figure 7. ．． , # & enter de' ≧ s 7 value engineering 2I also theory;

Claims (1)

[Claims] 1. A magnetic disk, a magnetic head that performs at least one of recording and reproducing signals on the magnetic disk, means for rotating the magnetic disk, and a recording/reproducing device connected to the magnetic head. In a magnetic disk device comprising a circuit and means for moving the magnetic head on the magnetic disk, an interval between the magnetic head and the magnetic disk is 0.1.
μm or more, the saturation magnetic flux density at the tip of the magnetic pole of the magnetic head is 12 kG or more, and the magnetic recording medium of the magnetic disk is a coated medium with a coercive force of 700 Oe or more. . 2. A magnetic disk, a magnetic head that performs at least one of recording and reproducing signals on the magnetic disk, means for rotating the magnetic disk, a recording and reproducing circuit connected to the magnetic head, and the magnetic head. and a means for moving the magnetic head on the magnetic disk, wherein the distance between the magnetic head and the magnetic disk is 0.1.
μm or more, the saturation magnetic flux density at the tip of the magnetic pole of the magnetic head is 12 kG or more, and the magnetic recording medium of the magnetic disk is a continuous medium with a coercive force of 1200 Oe or more. 3. The distance between the magnetic head and the magnetic disk is 0.15μ
3. The magnetic disk device according to claim 1, wherein the magnetic disk drive is greater than or equal to m. 4. The magnetic anisotropy field of at least part of the magnetic pole of the magnetic head is 4 to 15 Oe, and the axis of easy magnetization is oriented in the track width direction on the magnetic disk. 3. The magnetic disk device according to any one of 3. 5. The magnetic disk device according to claim 4, wherein the magnetic anisotropy field of at least a portion of the magnetic pole of the magnetic head is 5 to 8 Oe. 6. The magnetic disk device according to claim 1, wherein the absolute value of the magnetostriction constant of at least part of the magnetic poles of the magnetic head is 5×10^-^7 or less. 7. At least a part of the magnetic pole of the magnetic head is made of CoN.
7. The magnetic disk device according to claim 1, wherein the magnetic disk device is made of one or more selected from bZr, CoWZr, and CoTaZr. 8. At least a part of the magnetic pole of the magnetic head is made of FeS
7. The magnetic disk device according to claim 1, wherein the magnetic disk device is formed of a multilayer film made of i and NiFe. 9. At least a part of the magnetic pole of the magnetic head is made of FeC
7. The magnetic disk device according to claim 1, wherein the magnetic disk device is formed of a multilayer film made of NiFe and NiFe. 10. A magnetic recording medium, a magnetic head that performs at least one of recording and reproducing signals on the magnetic recording medium, means for moving the magnetic recording medium relative to the magnetic head, and a connection to the magnetic head. In a magnetic recording device having a recording and reproducing circuit, at least a part of the magnetic pole of the magnetic head is made of an amorphous alloy with a saturation magnetic flux density of 12 kG or more, and the magnetic recording medium has a coercive force of 700 to 120 kG.
A magnetic recording device characterized in that it is a coating type medium of 0 Oe. 11. The coating type medium is CoγFe_2O_2, Fe
, at least one magnetic powder of Ba ferrite,
11. The magnetic recording device according to claim 10, wherein the magnetic recording device is coated on a substrate together with a binder material. 12. A magnetic recording medium, a magnetic head that performs at least one of recording and reproducing signals on the magnetic recording medium, means for moving the magnetic recording medium relative to the magnetic head, and a connection to the magnetic head. In the magnetic recording device having a recording/reproducing circuit, at least a part of the magnetic pole of the magnetic head is made of an amorphous alloy having a saturation magnetic flux density of 12 kG or more, and the magnetic recording medium has a coercive force of 1200 to 15 kG.
A magnetic recording device characterized by being a continuous medium of 00 Oe. 13. The magnetic recording device according to claim 12, wherein the continuous medium is a CoNi-based sputtering medium. 14. Claims 10 to 1, characterized in that the spacing between the magnetic recording medium and the magnetic head is 0.1 μm or more.
3. The magnetic recording device according to any one of 3.