JP2002230930A - Magnetic disk drive - Google Patents

Abstract

[PROBLEMS] To increase the storage density of a magnetic disk drive, an active head slider that can individually adjust the flying height to absorb processing variations and pressure differences and reduce the flying height of the magnetic head is effective. is there. However, when the recording / reproducing element is moved by the micro actuator, the pressure generated on the air bearing surface changes due to the deformation of the actuator, and the flying height and attitude angle change, which may make it impossible to adjust the desired flying height. is there. An element pad on which a recording / reproducing element is mounted is provided separately from a floating pad which forms an air bearing surface and generates air pressure balanced with a load. To reduce the pressure newly generated when the element pad is brought close to the disk surface within a range that does not affect the flying height, the area of the element pad is set to 0.0
Set between 01 and 0.01 square millimeters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure for realizing a high recording density of a magnetic disk drive.

[0002]

2. Description of the Related Art A magnetic disk drive has a rotating magnetic disk, and a magnetic head slider mounted with a recording / reproducing element and supported and radially positioned by a load beam. Reads and writes magnetic information recorded on the disk. The slider floats as an air-lubricated bearing by the wedge film effect of air, so that the disk and the slider do not come into direct solid contact. In order to increase the recording density of the magnetic disk device and thereby increase the capacity or reduce the size of the device, it is effective to reduce the distance between the slider and the disk, that is, the flying height of the slider.

Conventionally, in the design of the slider flying height, a margin has been provided in consideration of a reduction in the flying height due to variations in slider processing, a difference in atmospheric pressure in use, and the like. If this margin can be eliminated, the flying height of the recording / reproducing element can be reduced. To solve this problem, Japanese Patent Application Laid-Open No. 62-250570 has proposed a method in which a minute actuator typified by a piezoelectric body is incorporated as a part of a slider and the distance between the disk and the disk is finely adjusted by moving a recording / reproducing element.
A system proposed in this publication, in which the flying height of the recording / reproducing element is controlled by a minute actuator, is generally called an active head slider system.

[0004]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 62-2505
No. 70, and the active head slider method in which the recording / reproducing element is brought close to the disk surface by a micro actuator, as shown in the Vol. Although this is a very effective technique for reducing the recording density and improving the recording density, no specific guideline for the design of the air bearing surface has been disclosed yet. Generally, as the slider flying surface approaches the disk surface, the air pressure generated on the slider flying surface increases.
Therefore, when the flying surface of the active head slider is designed in accordance with the conventional slider flying surface design, if the pad on which the recording / reproducing element is mounted approaches the disk surface by the minute actuator, the pressure of the pad portion cannot be ignored. Is newly generated. As a result, there is a danger that the slider as a whole rises (separates from the disk surface) to a flying position where an air pressure sufficient to balance the applied load is generated, and it is not possible to achieve a target minute recording / reproducing element / disk surface distance. This is even more so when the minimum distance between the recording / reproducing element and the disk surface, such as 10 nm or less, is targeted.

An object of the present invention is to propose a slider structure capable of stably maintaining an extremely small flying height, and to realize a magnetic disk device achieving high-density recording.

[0006]

In order to achieve the above object, an active head slider according to the present invention is provided with a recording head separately from a flying pad which generates an air pressure balanced with a load and determines a flying height and a posture angle. A pad on which a reproducing element was mounted and which did not generate a large amount of air pressure (hereinafter referred to as an element pad) was provided. Also, in order not to generate a large air pressure that affects the overall flying height at the element pad,
The element pad area is 0.001 square millimeter to 0.
01 mm2 or the ratio of the element pad area to the total floating pad area is 0.5% to 5%.
% Range.

With the above configuration, the flying height and the attitude angle of the entire slider are hardly affected by the displacement of the minute actuator. Therefore, a very small distance between the recording / reproducing element and the disk surface of 10 nm or less (hereinafter referred to as an element part floating clearance) can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a magnetic disk drive according to one embodiment of the present invention. The slider 1 has a recording / reproducing element for recording / reproducing magnetic information. The magnetic disk 2 stores magnetic information and rotates as shown. The load beam 3 has a spring function of applying a load for pressing the slider 1 to the disk surface while positioning the slider 1 in the disk radial direction. The ramp 4 is provided for the slider to evacuate from the disk before the apparatus is stopped or when there is no read / write command for a certain period of time. The slider 1 performs a seek operation together with the load beam 3 in the radial direction of the disk 2 as shown in the figure, and performs recording and reproduction on the entire disk surface. In this embodiment, the slider and its support mechanism perform a radial seek operation by a rotational movement, but there is also a mechanism that performs a radial seek operation by a linear movement.

FIG. 2 is a perspective view of the active head slider shown in FIG. A slider 1 has a recording / reproducing element 10 for reading and writing magnetic information on a magnetic disk, and a deforming means 1 for displacing the recording / reproducing element 10 in the direction of the arrow shown in the figure.
1 and a floating pad 12 of an air bearing for floating the slider so that the slider does not make solid contact with the disk by utilizing the flow of air.
It has. The dimensions of the slider used in this embodiment are so-called pico slider standards. That is, the thickness of the slider (vertical direction in the figure) is 0.3 mm, the length in the air flow direction (lateral direction in the figure) is 1.25 mm, and the length in the width direction is 1 mm.
It is.

FIG. 3 is a perspective view of a specific example of the active head slider shown in FIG. 2, viewed from the floating surface side, contrary to FIG. The recording / reproducing element 10 is provided so as to cover the element pad 13. The slider flying surface is composed of three heights: a reference height surface 15, an intermediate height surface 14, and pad surfaces 12 and 13. As shown in the figure, two floating pads 12 are provided on the empty inflow side and two on the outflow side. The intermediate height surface 14 protrudes from the reference height surface 15 by 0.7 μm to 1 μm. Pad surface 1
The projections 2 and 13 further project from the intermediate height surface 14 by 0.1 μm to 0.2 μm. An intermediate height surface 14 exists around the floating pad 12, particularly on the air inflow side (the side opposite to the recording / reproducing element pad). However, the surface close to the air inflow side of the element pad 13 is the reference height surface 15, and is characterized in that the intermediate height surface 14 does not exist.

In this embodiment, the active head slider having the above dimensions is shown, but the effect of the present invention is not limited to the above dimensions.

The recording / reproducing element 10 of this embodiment is separated into an inductive type recording element and a reproducing element utilizing a magnetoresistance (MR) effect, and is formed by a lithography process. The effect of the present invention is the same even if the recording / reproducing element is used. Further, although the number of the recording / reproducing element 10 and the element pad 13 in this embodiment is one, the effect of the present invention is the same even if there are two or more.

The slider according to the present embodiment is configured to be deformable in a direction perpendicular to the disk surface so that the recording element unit does not contact the disk surface during loading and unloading. This deformation mechanism will be described with reference to FIG.

The deforming means 11 of this embodiment comprises a thin film of a piezoelectric material typified by lead zirconate titanate (PZT), which is layered on a slider base material by sputtering between a thin film of platinum serving as an electrode. This is a unimorph type piezoelectric actuator formed between the piezoelectric actuators. Notches are provided by etching at predetermined distances on both sides of the recording / reproducing element of the slider so that deformation in the direction of the arrow in the drawing is likely to occur. Further, in the portion of the slider on which the recording / reproducing element is mounted, a groove formed by etching is provided on the side opposite to the surface on which the piezoelectric thin film is provided so as to be connected to the cut portion. The two floating pads 12 on the air outflow side are respectively provided outside the cut portions.

When a voltage is applied between the electrodes, the piezoelectric body extends in a direction perpendicular to the electric field. The surface of the base material on the piezoelectric body side is stretched by being pulled by the piezoelectric body, but the surface on the side opposite to the piezoelectric body is not particularly stretched because no force is applied, and as a result, the actuator tip is displaced downward in the figure. I do. If the slider base material is silicon, the actuator length is 0.5 mm, the actuator thickness is 0.05 mm, and the thickness of the PZT piezoelectric thin film is about 1 μm, the tip displacement when a voltage of 10 V is applied is 1
A displacement of about 5 nm is sufficient for adjusting the flying height of the recording / reproducing element.

As a method of forming the piezoelectric thin film, other than the above-described sputtering, another thin film forming method such as a liquid phase supply method called a sol-gel method may be used. Instead of forming the piezoelectric thin film on the base material of the slider, a layered piezoelectric element may be attached on the base material.

As a method other than using a piezoelectric thin film for the driving means 11, for example, a bimetallic actuator in which a plurality of layers having different coefficients of thermal expansion are formed and thermally expanded and deformed by resistance heat generated by flowing an electric current, An electric actuator, an electromagnetic actuator and the like can be given.

The active head slider according to the present embodiment absorbs variations in flying height due to variations in slider processing and differences in operating pressure by finely adjusting the element portion floating gap during actual use. It is controlled so as to realize a limited element part floating gap.

More specifically, when the power of the magnetic disk drive is turned on, the disk is rotated until a predetermined number of rotations is reached. Thereafter, the slider 1 moves on the ramp 4 toward the inner peripheral side of the disk 2. When the slider comes above the disk surface, the slider flies due to the flying effect of the slider due to the air flow generated as the disk rotates. At this time, the recording element portion of the slider has been deformed by the piezoelectric element in a direction not to contact the disk. After the slider floats on the disk surface, the slider portion gradually lowers the floating gap of the element portion until contact with the slider is detected (the voltage is gradually changed by the deforming means 11). When a contact is detected, it is returned by a certain amount. The required applied voltage at that time is stored in a memory. For contact detection, noise in reproduction output (so-called thermal asperity) due to contact heat is used. Next, the slider moves to the outer peripheral portion of the disk to perform the same operation, and the necessary applied voltage is stored. At the time of actual recording / reproducing, the required voltage applied to the track existing at that time is interpolated from the required voltages applied to the inner peripheral portion and the outer peripheral portion stored in advance and applied.

With the above control method, it is possible to absorb variations in the flying height due to variations in slider processing, atmospheric pressure differences in the use environment, and differences in the inner and outer circumferences of the slider position.

When there is no recording / reproducing command for a while, the slider 1 retreats (unloads) to the ramp 4 and returns (loads) from the ramp 4 onto the disc. In order to prevent collision, the deformation means 11 is acted on in advance in the upper part of FIG. 2 (in the direction in which the element part floating clearance is widened).

Next, the air pressure generated on the floating surface of the active head slider of the present invention will be described.

FIG. 4 is a graph showing the levitation force generated at the element pad portion in the active head slider of the embodiment shown in FIGS. The levitation force was calculated by an analytical method for obtaining the pressure distribution by solving the thin film gas lubrication equation. The vertical axis is not the levitation force itself, and the element portion levitation gap is 20 n in the initial state where the actuator is not deformed.
The ratio of the difference between the levitation force at m and the levitation force at the time when the actuator portion is deformed and the element portion levitation gap becomes 5 nm while keeping the flying height and attitude angle of the entire slider as they are is shown with respect to the applied load. . The horizontal axis indicates the area of the element pad. The ratio to the total floating pad area is shown in parentheses on the horizontal axis scale.

As shown in FIG. 4, when the element pad area exceeds 0.01 mm 2, the levitation force fluctuation of 3% or more of the applied load is caused by the deformation of the actuator. In this embodiment, from the viewpoint of impact resistance when an external impact is applied, the applied load is set to about 30 mN, and when a levitation force of 3% or more of the load is generated, a minute force is applied against the generated levitation force. It becomes difficult for the actuator to deform. Therefore, the element pad area is 0.01
Must be less than square millimeter.

On the other hand, the manufacturing limit of a recording / reproducing element separated into an inductive recording element and a reproducing element utilizing the magnetoresistance (MR) effect is 30 μm in length and 30 μm in width.
It is about μm. A recording / reproducing element smaller than this cannot be manufactured by extension of the current technology. Therefore, the area of the element pad on which the recording / reproducing element is mounted is necessarily 0.001 square millimeter or more.

In this manner, the area of the element pad of the active head slider is defined as 0.001 mm 2 to 0.01 mm 2. In this case, the ratio of the element pad area to the total floating pad area is 0.5% to 5%.

Another embodiment of the present invention will be described with reference to FIG. The numbers used in the figures are the same as those in FIGS. The difference between this embodiment and the previous embodiment is that a floating pad 12 is provided at the remaining center portion by piercing the air outflow end side of the slider in a U-shape. Further, the piezoelectric element is provided on the side opposite to the air bearing surface so as to protrude from the U-shaped portion. Except for the portion where the floating pad 12 of the U-shape is provided, the height is lower than the reference plane. Further, the recording / reproducing element is provided at the air outflow end which remains in the U shape.

In FIGS. 2 and 3, the element pad 13 is deformed by the deforming means 11, but in this embodiment, the element pad 13 is deformed.
The floating pad 12 is deformed. Floating pad 12
When the disk is deformed so as to approach the disk surface (downward in the figure), the air pressure generated at the floating pad increases, so that the flying height of the entire slider increases to balance the applied load, and eventually the element part floating clearance is increased. growing.
Conversely, when the flying pad 12 is deformed away from the disk surface (upward in the figure), the air pressure generated at the flying pad is reduced, so that the flying height of the entire slider is reduced to balance the load load, and eventually The element part floating gap becomes small. For the same reason as in the previous embodiment,
Also in the present embodiment, in order to reduce the pressure generated at the element pad, the area of the element
It is good to set it as 01 square millimeter-0.01 square millimeter.

[0030]

According to the floating surface structure of the present invention, an element pad on which a recording / reproducing element is mounted is provided separately from the floating pad for determining the flying height and the attitude angle by generating air pressure balanced with the applied load. , And the area of the element pad is set to 0.
According to the floating surface structure in which the element pad area is set to 001 square millimeters to 0.01 square millimeters or the ratio of the element pad area to the total floating pad area is set to 0.5% to 5%, the element pad portion affects the entire floating amount. Does not generate such large air pressure. Therefore, the flying height and attitude angle of the entire slider are hardly affected by the displacement of the minute actuator, and a minute element gap of 10 nm or less can be easily obtained.

When the floating height of the element portion can be adjusted, the floating margin for processing variations and the like is eliminated, and the clearance of the element portion is reduced, the magnetic clearance is narrowed, and the recording density of the magnetic disk device is increased. Can be. Also, at the time of loading / unloading or when a zero gravity state due to a drop is sensed, the element portion is separated from the disk, thereby preventing contact with the disk and improving reliability.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing details of the slider in FIG. 1 as viewed from a side opposite to a floating surface.

FIG. 3 is a perspective view showing details of the slider in FIG. 1 as viewed from a flying surface side.

4 is a diagram showing a guide for designing a flying surface of the slider of FIG. 3;

FIG. 5 is a perspective view of a slider according to another embodiment of the present invention.

[Explanation of symbols]

1 ... Slider, 2 ... Disk, 3 ... Load beam, 4 ...
Lamp, 10 ... recording / reproducing element, 11 ... deforming means, 12 ...
Floating pad, 13 ... element pad, 14 ... middle height surface, 1
5: Reference height surface.

Continued on the front page (72) Inventor Hideaki Tanaka 2880 Kozu, Kofu, Odawara City, Kanagawa Prefecture Inside Storage Systems Division, Hitachi, Ltd. (72) Inventor Yoshihiko 2880 Kozu, Kozu, Hitachi, Ltd. F term (reference) 5D042 NA02 PA01 PA05 QA03 5D059 AA01 BA01 CA12 DA18 DA26 EA02

Claims (3)

[Claims] 1. A magnetic disk, a rotating mechanism for the magnetic disk, a slider having a plurality of floating pads, and a recording / reproducing element for recording / reproducing information on a side of the slider facing a side surface of the magnetic disk. A magnetic disk drive comprising a mechanism for supporting the slider and positioning the slider in the radial direction of the magnetic disk, the slider comprising: a drive mechanism for driving a part of the slider in a direction substantially perpendicular to a disk surface; Wherein at least three or more pads per slider are provided, and one or more pads for mounting the recording / reproducing element are provided per slider in addition to the floating pads. 2. The magnetic disk drive according to claim 1, wherein the area of the pad on which the recording / reproducing element is mounted is 0.00.
A magnetic disk drive characterized by being in the range of 1 square millimeter to 0.01 square millimeter. 3. The magnetic disk drive according to claim 1, wherein a ratio of an area of the pad on which the recording / reproducing element is mounted to a total area of the floating pad is in a range of 0.5% to 5%. Characteristic magnetic disk drive.