JP2000182205A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic disk device which secures the safety of data and which uses the vertical magnetic recording medium of high track density without changing the head structure of the magnetic disk device by limiting a relation among the film thickness of a magnetic pole, track width, a yaw angle and a track pitch. SOLUTION: An MR element arranged between an upper shield and a lower shield 14 is used as a magnetic head. A merge-type MR head having a ring-type recording head forming a recording gap 13 between an upper magnetic pole 11 and the upper shield 12 is used while using the reproduction head upper shield 12 as the lower magnetic pole of a recording part. Magnetic pole thickness TUP in the floating face of the upper magnetic pole 11, width WUP, an angle (a) which a direction orthogonal to a recording track and the width direction of a recording head make, and a tracking pitch TP satisfy TP>TUP×sina+WUP×cosa in all magnetic head positions.

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, and more particularly, to a magnetic disk for positioning a magnetic head on a recording track provided on a disk-shaped perpendicular magnetic recording medium using a rotary actuator to record information. It relates to a disk device.

[0002]

2. Description of the Related Art Longitudinal magnetic recording (in-plane magnetic recording)
Then, the recording magnetic field generated from the magnetic recording head is shown in FIG.
As shown in FIG. 3A, the width of the recording magnetic field which is concentrated in the vicinity of the recording gap 13 formed by the upper magnetic pole 11 and the lower magnetic pole 12 of the ring type magnetic recording head and the yaw angle is other than zero is limited. Depends on the recording gap length and hardly depends on the film thickness of the upper magnetic pole 11. In a magnetic disk drive using a longitudinal magnetic recording medium, the upper end of the upper magnetic pole is
At the radius position where the yaw angle is large, the track overlaps the adjacent track. Here, the upper magnetic pole 11 is a magnetic pole that gives a recording magnetic field last to the magnetic recording medium among the two magnetic poles of the ring-type magnetic recording head, that is, a magnetic pole at the rearmost end in the running direction of the magnetic head. The yaw angle is an angle between a direction perpendicular to the recording track and the width direction of the magnetic recording head.

In a combination of a single-layer perpendicular magnetic recording medium and a ring-type recording head, as shown in FIG. 2B, the vertical magnetic field component near the recording gap 13 formed by the upper magnetic pole 11 and the lower magnetic pole 12 is used. Recording is performed, and the width of the recording magnetic field is almost independent of the thickness of the upper magnetic pole 11.

For a perpendicular magnetic recording medium having a soft magnetic underlayer, a single pole head having a structure different from that of a conventional ring head has been generally used for both recording and reproduction. It has been reported that recording is performed using a thin film type single pole head, but the problem associated with changes in yaw angle is not considered (Journal of the Japan Society of Applied Magnetics, Vol.
22, No.S3, 1998 "Evaluation of digital characteristics of double-layer perpendicular magnetic recording by single pole recording head / differential waveform conversion").

[0005]

In recent years, an MR element or a GMR element having high reproduction sensitivity has been developed as a read-only element. In a conventional longitudinal recording medium, a magnetic head combining this read-only element and a ring type recording head has been developed. As a magnetic head that is used and combined with a perpendicular magnetic recording medium, it is necessary to use a recording / reproducing separation type magnetic head.

When a ring-type head is used as a magnetic recording head for a perpendicular magnetic recording medium having a soft magnetic underlayer, as shown in FIG. 2C, the width depending on the thickness of the upper magnetic pole 11 is increased. The resulting magnetic field is generated. In the combination of a perpendicular magnetic recording medium having a soft magnetic underlayer and a single pole type recording head, as shown in FIG. 2D, the recording magnetic field distribution is such that the recording magnetic field near the upper pole of the ring type recording head is small. And a magnetic field having a width depending on the thickness of the main pole 15 is generated. Since the lower magnetic pole 12 has a structure wide in the track width direction, the magnetic field does not concentrate, and the influence on the width (recording width) of the magnetic field is sufficiently small.

FIG. 3 is a diagram for explaining a state in which the recording width when recording is performed on a perpendicular magnetic recording medium having a soft magnetic underlayer by a read / write separation type composite magnetic head according to the yaw angle. When the recording gap is parallel to the track width direction as shown in FIG. 3A, that is, when the yaw angle is zero, the recording width depends on the width of the upper magnetic pole 11 and does not depend on the upper magnetic pole thickness. On the other hand, when the yaw angle is other than zero as shown in FIG. 3B, there is a problem that the recording width is effectively increased depending on the thickness of the upper magnetic pole.

In order to make the yaw angle always zero, a method using a two-stage actuator or a method using a linear actuator can be considered. The actuator has a problem that the size of the device is increased.

The present invention relates to a magnetic disk drive having a perpendicular magnetic recording medium having a soft magnetic backing layer and a read / write separation type magnetic head, which performs recording with a ring type magnetic recording head or a single pole type magnetic recording head. It is an object of the present invention to provide a magnetic disk drive capable of solving the above-mentioned problems without changing the magnetic head positioning mechanism of the conventional magnetic disk drive and performing recording with a high track density.

[0010]

According to the present invention, the geometric shape of the magnetic poles of the magnetic recording head is limited, and the recording width of the magnetic recording head exceeds the track width at any radial position on the magnetic disk. The above object is achieved by eliminating the above. That is, the present invention relates to a magnetic disk device including a perpendicular magnetic recording medium having a soft magnetic backing layer and a read / write separation type composite magnetic head, wherein the read / write separation type composite magnetic head sandwiches the read element and the read element. The magnetic pole thickness TUP at the air bearing surface of the magnetic pole, the width WUP, and the direction orthogonal to the recording track are provided. And a track pitch TP satisfying TP> TUP × sina + WUP × cosa at all magnetic head positions.

Considering the margin of the servo control of the magnetic head, the magnetic pole thickness TUP and the width WUP of the magnetic pole that finally applies the recording magnetic field to the magnetic recording medium are TP × 0.7> TUP at all the magnetic head positions. It is preferable to design so as to satisfy × sina + WUP × cosa.

Further, when the thickness of the magnetic pole above the air bearing surface is TUP2, the magnetic pole shape may always be such that TP> TUP × sina + WUP × cosa and TP ≦ TUP2 × sina + WUP × cosa. You can achieve your goals. Also in this case, in consideration of the margin of the servo control of the magnetic head, it is preferable that the design is made so as to satisfy TP × 0.7> TUP × sina + WUP × cosa and TP × 0.7 ≦ TUP2 × sina + WUP × cosa.

[0013]

Embodiments of the present invention will be described below. FIG. 1 shows a schematic diagram of the configuration of a magnetic disk drive according to the present invention. The magnetic disk drive includes a perpendicular magnetic recording medium 21 having a soft magnetic underlayer, and a separate read / write composite magnetic head 22 for recording and reproducing on and from the magnetic recording medium 21. The magnetic head 22 is attached via a suspension arm 23 to a rotary actuator 24 that rotates around a fulcrum P for positioning. The distance between the recording head gap and the fulcrum P is Lg.
It is. The head gap portion is provided substantially perpendicular to a straight line drawn from the fulcrum P to the gap portion.
The distance between the rotation center Q of the magnetic recording medium 21 and the fulcrum P is Lq. At this time, the angle between the straight line connecting the points Q and G at the radial position R of the magnetic recording medium 21 and the recording gap, that is, the yaw angle a is uniquely determined. FIG. 4 is an enlarged view of a slider portion of the magnetic head. A magnetic head element 25 is provided at the tip of the slider.

FIG. 5 is a schematic view of the cross-sectional structure of the magnetic recording medium 21. A base layer 52 for controlling the orientation of a magnetic layer is provided on a substrate 51, a backing layer 53 having soft magnetic properties is provided thereon, a recording layer 54 is further provided thereon, and a medium surface is provided thereon. A protective layer 55 for protection is provided.

First, a first embodiment of the present invention will be described. FIG. 6 shows the element section 25 of the magnetic head shown in FIG.
FIG. 4 is an enlarged view of FIG. In the present embodiment, an MR element 33 disposed between the upper shield 12 and the lower shield 14 in the reproducing section is used as the magnetic head, and the upper shield 12 of the reproducing head is also used as the lower magnetic pole of the recording section. A merge type MR head having a ring type recording head which forms a recording gap 13 with the shield 12 is used. The magnetic pole thickness on the air bearing surface of the upper magnetic pole 11 is TUP, and the width is WUP. FIG. 7 is a cross-sectional view for explaining the magnetic pole structure of the recording head, and shows the relationship between the upper magnetic pole 11 and the lower magnetic pole (upper shield) 12.

At the radial position where the yaw angle is close to zero, the width (recording width) of the recording magnetic field of the ring type magnetic recording head shown in FIG. 6 is substantially equal to the upper magnetic pole width W as shown in FIG.
Matches UP. On the other hand, when the yaw angle increases, FIG.
As shown in (b), the recording width changes depending on the magnetic pole thickness TUP of the upper magnetic pole 11. The relationship between the size of the upper magnetic pole 11, the yaw angle, and the recording width will be described with reference to FIG. From FIG. 8, the upper magnetic pole thickness is TUP and the upper magnetic pole width is W.
When the UP and the yaw angle are a, the projection length of the upper magnetic pole 11 in the track width direction, that is, the recording width is represented by the following equation. TUP × sina + WUP × cosa

The object of the present invention can be achieved by setting the recording width to be equal to or less than the track width. However, in this embodiment, the recording width is determined by the radius R at which the yaw angle is maximized in consideration of the positioning error of the magnetic head. It is designed to be 70% or less of the track pitch, and is designed to satisfy the following relationship. TP x 0.7> TUP x sina + WUP x cosa

Accordingly, the recording width always falls within the track width regardless of the radial position of the recording head at any radial position. Therefore, data security is improved for a perpendicular magnetic recording medium having a soft magnetic underlayer. It is possible to perform recording with a high track density while ensuring the recording. Although the ring-type recording head has been described here, the same applies to the case where a read / write separated composite magnetic head having a single-pole type magnetic recording head structure is used, only by replacing the upper magnetic pole in the above description with the main magnetic pole. I can say that.

Next, a second embodiment of the present invention will be described. This embodiment has the same configuration as the first embodiment except that the structure of the recording element is different. FIG. 9 is a cross-sectional view of the recording element according to the present embodiment. In the case of the magnetic pole structure whose cross section is shown in FIG. 7, the magnetic pole thickness TUP of the upper magnetic pole (main magnetic pole of the single magnetic pole type magnetic recording head) 11 of the ring type magnetic recording head may be reduced as a whole in order to satisfy the above relational expression. There is no problem when the saturation magnetic flux density (Bs) of the magnetic pole material is sufficiently high or when the coercive force of the magnetic recording medium is sufficiently small, but when Bs is not sufficiently high, the recording magnetic field intensity decreases. In some cases, a magnetic field required for recording cannot be obtained.

Therefore, in this embodiment, as shown in FIG.
Processing is performed only in the vicinity of the air bearing surface of the upper magnetic pole (main magnetic pole) 41 to reduce the magnetic pole thickness TUP1 at the air bearing surface, and to increase the magnetic pole thickness TUP2 at a portion away from the air bearing surface that does not directly affect the recording magnetic field distribution. I have. Thereby, saturation of the entire magnetic pole can be avoided.

FIG. 10 shows a view from the air bearing surface of the upper magnetic pole 41 at this time. As shown in FIG. 10, at a position distant from the air bearing surface, TP × 0.7> TUP1 × sina + WUP × cosa, and at the air bearing surface, TP ≦ TUP2 × sina + WUP × cosa, so that the ring type magnetic recording is designed. Whether using a head or a single pole head,
Since the recording width by the recording head can always be kept within the track width at an arbitrary radius position of the perpendicular magnetic recording medium while avoiding saturation of the entire magnetic pole, data safety can be secured for a perpendicular magnetic recording medium having a soft magnetic underlayer. It is possible to perform recording with a high track density while ensuring the recording performance.

[0022]

According to the present invention, the relationship between the film thickness and track width of the upper magnetic pole, the yaw angle, and the track pitch is limited, so that the head structure and positioning mechanism of the conventional magnetic disk drive can be changed. In addition, it is possible to realize a magnetic disk device using a high-track-density perpendicular magnetic recording medium ensuring data security.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a magnetic disk drive according to the present invention.

FIG. 2 is an explanatory diagram showing an outline of a recording magnetic field distribution.

FIG. 3 is a diagram illustrating a recording width that changes depending on a yaw angle.

FIG. 4 is a schematic view of a slider portion of the magnetic disk drive.

FIG. 5 is an explanatory diagram of a cross-sectional structure of a magnetic recording medium.

FIG. 6 is a schematic view of an example of a magnetic head viewed from a floating surface side.

FIG. 7 is a diagram illustrating an example of a magnetic pole structure of a magnetic recording head according to the present invention.

FIG. 8 is an explanatory diagram of the condition of the upper magnetic pole of the recording head according to the present invention.

FIG. 9 is an explanatory diagram of another example of the magnetic pole structure of the magnetic recording head according to the present invention.

FIG. 10 is an explanatory diagram of another example of the condition of the upper magnetic pole of the magnetic recording head according to the present invention.

[Explanation of symbols]

11 upper magnetic pole (main magnetic pole), 12 upper magnetic shield (lower magnetic pole), 13 recording gap, 14 lower magnetic shield, 1
5 ... Main magnetic pole, 21 ... Magnetic recording medium, 22 ... Slider and magnetic head, 23 ... Suspension arm, 24 ... Rotary actuator, 33 ... MR element, 41 ... Floating surface processing upper magnetic pole, 42 ... Upper shield (lower magnetic pole)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenya Ito 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 5D033 AA05 BA13 BB43 BB51 5D091 AA10 CC13 DD03 HA06 5D093 AA05 AD12 AE05 BE07 DA02

Claims (4)

[Claims] 1. A magnetic disk drive including a perpendicular magnetic recording medium having a soft magnetic underlayer and a read / write separation type composite magnetic head, wherein the read / write separation type composite magnetic head includes a read element and a read element. A pair of magnetic shields sandwiched and arranged,
A magnetic pole disposed on the downstream side in the running direction with respect to the pair of magnetic shields, wherein a magnetic pole thickness TUP on the air bearing surface of the magnetic pole, a width WUP, a direction perpendicular to the recording track, and a width direction of the recording head are defined as: Angle a and track pitch T
A magnetic disk drive wherein P satisfies TP> TUP × sina + WUP × cosa at all magnetic head positions. 2. The magnetic disk drive according to claim 1, wherein TP × 0.7> TUP × sina + WUP × cosa is satisfied at all magnetic head positions. 3. The magnetic disk drive according to claim 1, wherein when the thickness of the magnetic pole above the air bearing surface is TUP2, TP> TUP × sina + WUP × cosa and TP ≦ TUP2 × sina + WUP × cosa are satisfied. A magnetic disk device characterized by the above-mentioned. 4. The magnetic disk drive according to claim 3, wherein TP × 0.7> TUP × sina + WUP × cosa and TP × 0.7 ≦ TUP2 × sina + WUP × cosa.