JP3097925B2 - Magnetic disk drive - Google Patents

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 drive having an oscillating head actuator.

[0002]

2. Description of the Related Art In a magnetic disk drive, performance improvements such as high density and large capacity and high density and small size are progressing.

As one of the methods for reducing the size of a magnetic disk drive, the use of an oscillating head actuator for a positioning mechanism for moving a head to an arbitrary track has been generalized. The oscillating head actuator moves the head slider substantially in the radial direction of the recording medium (disk) by rotating the head actuator having the head slider fixed to the tip of the arm. In this case, the trajectory of the head slider becomes an arc as shown in FIG. 3, and the yaw angle of the head actuator with respect to the concentric track of the disk changes depending on the radial position of the recording medium.

On the other hand, the recording density of a magnetic disk device can be considered as being divided into a linear recording density in a disk circumferential direction and a track recording density in a radial direction.

In order to improve the linear recording density, it is important to stably reduce the gap (flying height) between the recording disk and the head slider. Conventionally, the head is floated on a disk rotated at a high speed, and both ends of a slider surface of the head are formed into a ski sled, and a head element is provided at a rear end of the head (a double-headed head slider). Have achieved. In this method, since the rigidity of the air film can be increased, high flying stability and a small flying height (submicron) can be ensured. In addition, a vertically-sliding head slider like a single ski effectively utilizes the entire slider surface,
It is known to improve flying stability. However, at present, a minimum of two sleds (twin barrel type) are generally used in consideration of workability and the like.

When the track recording density is improved, the signal output is reduced, but the noise due to the leakage signal (side cross stroke) from the adjacent track is increased, and the signal quality is reduced. As a method of preventing this, a method of providing concentric grooves (grooves) between adjacent tracks of a recording layer on a disk (groove disk) has been proposed.

FIGS. 4A, 4B, and 4C are plan views of the groove disk 10 and the double-headed head slider 11, respectively.
It shows an enlarged side view and an enlarged sectional view. Reference numeral 12 denotes a groove provided on the surface of the groove disk 10.

[0008]

Here, as shown in FIG. 5A, a vertically-elongated head slider 15 is yawed with respect to a groove disk 10 having a groove 12 having a constant groove pitch, width and depth. Consider the case where the angles are 0 ° and θ ° respectively.

When the yaw angle is 0 °, the cross section of the head slider 15 along the groove 12 at the position G1 and the pressure distribution are shown in FIG.
, The head slider 15 receives a sufficient flying force.

In the case of the yaw angle θ °, the cross section of the head slider 15 along the groove 12 at the position G2 and the pressure distribution are shown in FIG.
, The flying force received by the head slider 15 decreases.

For this reason, the relationship between the yaw angle and the flying height of the head slider is expressed as shown in FIG. 5D. As the yaw angle increases, the flying height of the head slider decreases significantly. That is, the head slider 1 that scans the disk 10
5, the flying height of the head slider 15 changes due to a change in the yaw angle in accordance with the position in the disk radial direction, and there is a problem that the recording / reproducing characteristics differ depending on the position in the disk radial direction.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a magnetic disk device in which the flying height of a head slider is constant and the recording / reproducing characteristics are constant regardless of the position in the disk radial direction.

[0013]

According to the magnetic disk drive of the present invention, a groove disk having a concentric or spiral groove formed on a recording surface is scanned by a head slider which is moved by a track by an oscillating head actuator. In the magnetic disk drive, the width of the groove is reduced in response to a change in which the yaw angle, which is the inclination between the head slider and the groove in the longitudinal direction, increases in accordance with the radial position of the groove disk.

Further, the depth of the groove is reduced in accordance with the change in which the yaw angle increases.

Further, the width between adjacent widths is increased in accordance with the change in which the yaw angle increases.

[0016]

In the present invention, as the yaw angle increases, the width of the groove decreases, or the depth of the groove decreases, or the width between the grooves increases. The flying height can be kept constant, the flying height becomes constant at any position in the radial direction of the groove disk, and the recording / reproducing characteristics become constant.

[0017]

FIG. 1 is a sectional view of an embodiment of the apparatus of the present invention. In the figure, reference numeral 20 denotes a vertically-elongated head slider, and reference numeral 21 denotes a groove disk. Head slider 2
0 is W (for example, 200 μm) in the disk radial direction, the bottom surface 20a of the head slider 20 facing the disk 21 and the inner and outer side surfaces 20b and 20c in the disk radial direction. Corners are chamfered.

The groove disk 21 is provided with a plurality of concentric or spiral grooves 22 on the recording surface. Here, the pitch of the groove 22 is P (for example, 10 μm), the width of the groove 22 is b (for example, 2 μm), and the depth of the groove 22 is d (0.5 μm).
m) and the groove disk 21 of the head slider 20
The flying height from the surface is h (for example, 0.05 μm).
As shown in FIG. 2, the magnetic disk drive of FIG. 1 has a multi-rail slider 3 having slider grooves 30a, 30b, 30c.
1 and a combination of a flat disk 32 having no groove. In this case, the slider grooves 30a, 30b,
The groove pitch of each of the grooves 30c is P, the groove width is b, the groove depth is d, and the flying height is h, which are the same as those in FIG.

The flying characteristics of the head slider 31 shown in FIG. 2 are obtained by numerically calculating the Reynolds equation by the finite element method. The relationship between the groove width b, the flying force F and the flying height h is approximately expressed by the following equation. Is represented.

F∝ (P−b) ² / h ² (1) By rewriting equation (1), the following equation is obtained.

H∝ (P−b) ^3/2 (2) It is apparent from equation (2) that changing the groove width b greatly changes the flying height.

On the other hand, the relationship between the groove depth d and the flying height h is not represented by a simple equation, and calculations are performed one by one by substituting each condition. However, the groove depth d is less than 10 times the flying height h. In this case, the flying height h becomes larger as the groove depth becomes shallower. However, if the groove depth is 10 times or more, the influence on the flying height h sharply decreases, and it can be considered that the groove is apparently opened to the atmosphere.

Here, since FIG. 2 is equivalent to FIG. 1, assuming that the groove depth d of the groove disk 21 shown in FIG. 1 is about 10 times the flying height h, the flying height h is calculated from the equation (2). (P
−b), and is in inverse proportion to the groove width b when the groove pitch P is constant.

Accordingly, the so-called rail width P corresponding to the yaw angle determined by the position of the head slider 20 in the radial direction of the disk.
By varying −b or the groove width b, it is possible to control the flying height to be constant.

Incidentally, the azimuth angle θ of the magnetic gap provided in the head slider 20 changes with the change of the yaw angle. Effective track width T corresponding to rail width Pb
The relationship between w and the azimuth angle θ is expressed by the following equation.

Tw = cos θ (3) As is apparent from the equation (3), the azimuth angle θ is ± 1.
In a small range of about 0 degrees, the effective track width Tw does not change so much.

Here, the yaw angle of the head slider 20 is set to 0 ° and the azimuth angle is set to 0 ° at the center position in the radial direction of the disk 21, and the yaw angle of the innermost position + 10 ° and the yaw angle of the outermost position −10 ° In this case, the groove width b is made smaller toward the inner periphery and the outer periphery with respect to the center position, or the groove depth d is made smaller. However, since the relative speed of the head slider 20 with respect to the disk 21 is smaller on the inner peripheral side than on the outer peripheral side, the groove width b or the groove depth d is reduced accordingly. In this case, since the azimuth angle at each of the innermost position and the outermost position is ± 10 °, the change of the effective track width Tw does not matter. When the yaw angle of the head slider 20 is 0 ° at the innermost peripheral position in the radial direction of the disk 21 and the yaw angle is −20 ° at the outermost peripheral position, the azimuth angle is 0 ° at the center position. Offset by 10 ° in the circumference, and make the groove width b narrower toward the outer circumference with respect to the innermost circumference position,
Alternatively, the groove depth d is reduced. Also in this case, since the azimuth angle at each of the innermost position and the outermost position is ± 10 °, the change of the effective track width Tw does not matter.

Instead of narrowing the groove width b, the rail width P
-B may be widened and is not limited to the above embodiment.

Further, the head slider 20 is not limited to a vertically elongated shape, but may be a circular or elliptical shape.

As described above, as the yaw angle increases, the width of the groove 22 decreases, the depth of the groove decreases, or the width between the grooves increases. The flying height of the slider can be kept constant, the flying height becomes constant at any position in the radial direction of the groove disk, and the recording / reproducing characteristics become constant.

Since the corners between the bottom surface 20a and the side surfaces 20b and 20c of the head slider 20 are chamfered,
Even when the yaw angle is large, a levitation force is easily generated, and damage to the disk surface can be reduced. Thus, rail processing is not required as in the conventional twin-barreled head slider, and processing of the head slider is simple.

[0032]

As described above, according to the magnetic disk drive of the present invention, the flying height of the head slider is constant irrespective of the position in the disk radial direction, and the recording / reproducing characteristics are constant, which is extremely useful in practice.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the apparatus of the present invention.

FIG. 2 is a sectional view of an apparatus equivalent to FIG.

FIG. 3 is a diagram for explaining a yaw angle.

FIG. 4 is a diagram for explaining a groove disk.

FIG. 5 is a diagram for explaining a relationship between a yaw angle and a flying height.

[Explanation of symbols]

 Reference Signs List 20 head slider 21 groove disk 22 groove

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasuyuki Sagara 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside of Fujitsu Limited (56) References JP-A-51-6505 (JP, A) Jpn. (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 21/21 G11B 5/82

Claims (3)

(57) [Claims] A concentric or spiral groove (2) is formed on a recording surface.
In a magnetic disk drive that scans the groove disk (21) on which the 2) is formed with a head slider (20) that is track-moved by an oscillating head actuator, according to the radial position of the groove disk (21). A magnetic disk drive characterized in that the width of the groove (22) is reduced in response to a change in the yaw angle which is the inclination between the head slider (20) and the longitudinal direction of the groove (22). 2. A concentric or spiral groove (2) on a recording surface.
In a magnetic disk drive that scans the groove disk (21) on which the 2) is formed with a head slider (20) that is track-moved by an oscillating head actuator, according to the radial position of the groove disk (21). A magnetic disk drive characterized in that the depth of the groove (22) is reduced in response to a change in the yaw angle which is the inclination between the head slider (20) and the longitudinal direction of the groove (22). 3. A concentric or spiral groove (2) on a recording surface.
In a magnetic disk drive that scans the groove disk (21) on which the 2) is formed with a head slider (20) that is track-moved by an oscillating head actuator, according to the radial position of the groove disk (21). A magnetic disk drive characterized in that the width between adjacent grooves (22) is increased in response to a change in the yaw angle which is the inclination between the head slider (20) and the longitudinal direction of the grooves (22) increases. .