Patent Grant
7626786
This application claims priority from Japanese Patent Application No. JP2004-345532, filed Nov. 30, 2004, the entire disclosure of which is incorporated herein by reference.
The present invention relates generally to a magnetic head slider that flies with a fine clearance above a traveling recording medium or comes into intermittent contact with the traveling recording medium, a magnetic head assembly incorporating the magnetic head slider therein, and a magnetic disk drive. More specifically, the present invention relates to a magnetic head slider suitable for a magnetic disk drive in which a small-diameter disk having a diameter of 45.7 mm (1.8 in.) or less is used.
A magnetic head slider is supported by a flexure attached to a suspension. The magnetic head slider flies with a fine clearance above a magnetic disk or comes into intermittent contact with the magnetic disk so as to write or read data thereon or therefrom. Patent Document 1 (Japanese Patent Laid-open No. 2003-123422) discloses a negative pressure slider which is widely used at present.
A recent trend in the magnetic disk drive is shifted toward a compact magnetic disk drive using a small-diameter disk, to thus meet the need for a high recording density and aim at application to compact digital equipment. This trend raises a problem of a decrease in effective data area on a disk. As an approach to solving this problem, there is known a method for reducing the slider in size. There has been developed a compact slider representing reduction in dimension of about 70% of the above-described slider which is widely used at present.
A reduction in size of the slider, or in particular, a reduction in slider width and slider height can be about double the number of sliders which are taken from a wafer having the same size by using a single magnetic head fabricating apparatus. This also yields a benefit of cost reduction of the slider.
Because of a reduction in size involved with the compact slider, an area of the bearing surface decreases, resulting in that a lifting force by an air bearing characteristic is substantially decreased. A suspension load applied to the slider also should be made small in order to balance with the decreased lifting force. This trend is prominent in a low-speed 2.5-inch magnetic disk drive having a low-disk-speed and a drive using a magnetic disk having a diameter of 45.7 mm (1.8 inches) or less. This is because the lifting force by the bearing characteristic is directly proportional to the speed. The problem of the insufficient lifting force based on the air bearing characteristic cannot arise in the conventional 3.5-inch magnetic disk drive or a high-speed 2.5-inch magnetic disk drive offering a magnetic disk speed of 5400 rpm, 7200 rpm or the like. The problem of the reduced lifting force newly arises when magnetic disk drives using disks having a diameter as small as 25.4 mm (1 in.), 45.7 mm (1.8 in.) and the like have been put into practical applications. Problems arising from the marked decrease in lifting force include the following:
(1) The air bearing stiffness decreases, which degrades the flying characteristic of the slider. In particular, pitch stiffness (i.e., the air bearing stiffness in a longitudinal direction of the slider) is proportional to the length to about the second power. A reduced slider length, therefore, results in that the pitch stiffness is substantially decreased. Consequently, the flying height in a pitch direction severely fluctuates with respect to disturbance vibrations. In worst cases, part of the slider comes into contact with the medium.
(2) Because of the necessity of minimizing the suspension load, shock resistance of the drive during operation is reduced.
(3) A slider using both of positive and negative pressures has two zones: namely, a stable zone and a bi-stable zone. In the stable zone, a negative pressure is produced in a negative pressure area. In the bi-stable zone, the slider can take either one of two modes: namely, a high flying mode and a low flying mode. In the high flying mode, a positive pressure is produced even in the negative pressure area and the slider flies with a flying height of 1 μm or more. In the low flying mode, the slider flies with the originally designed flying height. In a system with a small suspension load, the slider enters the bi-stable zone, thereby frequently inducing the high flying mode so as to make it impossible to read or write data.
(4) The slider may come into contact with the disk at an inflow end when the flying height is reduced due to a decreased ambient pressure or the aforementioned disturbance vibrations or during slider loading (hereinafter referred to as “pitch down”). In such a case, a slider having a small suspension load and a short slider length cannot escape from such a situation, and therefore, is kept in that attitude. The continuous contact damages a contact portion of the disk, thereby dissipating information. This could eventually result in a crash.
(5) The reduced bearing area results in the decrease in the negative pressure as well as the decrease in lifting force. Accordingly, the decrease in flying height with respect to the decrease in ambient pressure becomes large, thus eliminating a flying margin.
(6) When disk drives having high-disk-speeds, e.g., 7200, 10000, and 15000 rpm, record servo information to the magnetic disk, the disk speed is lowered to ½ to ⅓ of the normal speed. With the conventional compact slider, the decrease in flying height with respect to the speed is large, and the flying attitude is not stable, thereby making it impossible to accurately write servo information because of the disk surface contact vibration involved. In extreme cases, the aforementioned pitch down occurs, resulting in a crash at times.
It is a feature of the present invention to provide a magnetic head slider capable of lessening a decrease in lifting force.
It is another feature of the present invention to provide a magnetic head assembly in which a decrease in flying height can be alleviated even in the case of a decrease in ambient pressure.
It is a further feature of the present invention to provide a magnetic disk drive having an improved shock resistance characteristic.
It is a still further feature of the present invention to provide a magnetic head slider and a magnetic disk drive, in which pitch down can be prevented and any damage to a magnetic disk can be avoided.
A magnetic head slider according to an aspect of the present invention comprises: a slider including two air bearing surfaces disposed on both sides on an air inflow side of a medium opposing surface; a shallowly grooved surface disposed between the air bearing surface and an air inflow end; side shallowly grooved surfaces disposed rearward of the two air bearing surfaces and extending near an air outflow end; a center air bearing surface disposed at a widthwise center of the air outflow end of the medium opposing surface; a center shallowly grooved surface disposed on the air inflow side of the center air bearing surface; and a deeply grooved surface surrounded by the two air bearing surfaces and the center air bearing surface; and a magnetic head disposed at the center air bearing surface; wherein the ratio of a slider length Lx to a slider width Ly satisfies the following inequality: 1.35≦Lx/Ly≦1.8, the slider width Ly being 0.8 mm or less.
In some embodiments, the slider length Lx is 0.945 mm or more and 1.44 mm or less. Each of the shallowly grooved surface from the two air bearing surfaces and the center shallowly grooved surface from the center air bearing surface has a depth of 200 nm or less, and the deeply grooved surface from the two air bearing surfaces and the center air bearing surface has a depth of 1500 nm or less.
A magnetic head slider according to another aspect of the present invention comprises: a slider including two air bearing surfaces disposed on both sides on an air inflow side of a medium opposing surface; a connection air bearing surface for connecting the two air bearing surfaces to each other on the air inflow side; two pads disposed on both sides of an air inflow end of the medium opposing surface; a shallowly grooved surface disposed between the two air bearing surfaces and the connection air bearing surface, and the air inflow end; side shallowly grooved surfaces disposed rearward of the two air bearing surfaces and extending near an air outflow end; a center air bearing surface disposed at a widthwise center of the air outflow end of the medium opposing surface; a center shallowly grooved surface disposed on the air inflow side of the center air bearing surface; and a deeply grooved surface surrounded by the two air bearing surfaces, the connection air bearing surface and the center air bearing surface; and a magnetic head disposed at the center air bearing surface; wherein the ratio of a slider length Lx to a slider width Ly satisfies the following inequality: 1.35≦Lx/Ly≦1.8, the slider width Ly being 0.8 mm or less.
In specific embodiments, each of the two pads is the same in height as each of the air bearing surfaces.
A magnetic head slider according to another aspect of the present invention comprises: a slider including two air bearing surfaces disposed on both sides on an air inflow side of a medium opposing surface; a connection air bearing surface for connecting the two air bearing surfaces to each other on the air inflow side; deposition films disposed on an air outflow side of the two air bearing surfaces; two pads disposed on both sides of an air inflow end of the medium opposing surface; a shallowly grooved surface disposed between the two air bearing surfaces and the connection air bearing surface, and the air inflow end; side shallowly grooved surfaces disposed rearward of the two air bearing surfaces and extending near an air outflow end; a center air bearing surface disposed at a widthwise center of the air outflow end of the medium opposing surface; a center shallowly grooved surface disposed on the air inflow side of the center air bearing surface; and a deeply grooved surface surrounded by the two air bearing surfaces, the connection air bearing surface and the center air bearing surface; and a magnetic head disposed at the center air bearing surface; wherein the ratio of a slider length Lx to a slider width Ly satisfies the following inequality: 1.35≦Lx/Ly≦1.8, the slider width Ly being 0.8 mm or less.
In some embodiments, the deposition film has a thickness of 50 nm or less. The deposition film is a carbon film. The deposition film is formed at each of the two pads.
A magnetic head assembly according to another aspect of the present invention comprises: a magnetic head slider including a slider having: two air bearing surfaces disposed on both sides on an air inflow side of a medium opposing surface; a shallowly grooved surface disposed between the air bearing surface and an air inflow end; side shallowly grooved surfaces disposed rearward of the two air bearing surfaces and extending near an air outflow end; a center air bearing surface disposed at a widthwise center of the air outflow end of the medium opposing surface; a center shallowly grooved surface disposed on the air inflow side of the center air bearing surface; and a deeply grooved surface surrounded substantially by the two air bearing surfaces and the center air bearing surface; and a magnetic head disposed at the center air bearing surface, wherein the ratio of a slider length Lx to a slider width Ly satisfies the following inequality: 1.35≦Lx/Ly≦1.8, the slider width Ly being 0.8 mm or less; a flexure for holding the slider; and a suspension having the flexure fixed thereto, a pivot position, at which a load is applied to the slider, being deviated by 10% or more of the slider length toward the air inflow side from the center of the slider.
A magnetic disk drive according to another aspect of the present invention comprises: a magnetic head slider including a slider having two air bearing surfaces disposed on both sides on an air inflow side of a medium opposing surface; a shallowly grooved surface disposed between the air bearing surface and an air inflow end; side shallowly grooved surfaces disposed rearward of the two air bearing surfaces and extending near an air outflow end; a center air bearing surface disposed at a widthwise center of the air outflow end of the medium opposing surface; a center shallowly grooved surface disposed on the air inflow side of the center air bearing surface; and a deeply grooved surface surrounded by the two air bearing surfaces and the center air bearing surface; and a magnetic head disposed at the center air bearing surface, wherein the ratio of a slider length Lx to a slider width Ly satisfies the following inequality: 1.35≦Lx/Ly≦1.8, the slider width Ly being 0.8 mm or less; and a magnetic disk, on and from which data can be written and read by the magnetic head slider.
In some embodiments, the magnetic disk has a diameter of 45.7 mm or less. The height of a magnetic head slider is about 0.2 mm or less. Additionally, the height of a magnetic head slider in a magnetic disk drive is about 0.2 mm or less.
According to the present invention, a suspension load to the compact slider can be increased by about 1.4 times or more in comparison with the prior art. Accordingly, the shock resistance characteristic during operation can be enhanced by about 1.4 times or more.
Specific embodiments of the present invention will be described in detail with reference to
The height of each of the inflow side air bearing surfaces 2a and 2b is set to be the same as that of the center air bearing surface 2c. In addition, the heights of the inflow side shallowly grooved surface 4a, the side shallowly grooved surface 4b and the center shallowly grooved surface 4c are set to be the same as each other. A slider length Lx is 1.25 mm, a slider width Ly is 0.7 mm, and therefore, the ratio of the slider length Lx to the slider width Ly is 1.79. Moreover, a depth d1 of the shallowly grooved surface from the air bearing surface should be preferably 200 nm or less while a depth d2 of the deeply grooved surface from the air bearing surface should be preferably 1500 nm or less, although an appropriate value may be slightly varied according to a disk diameter or a disk speed in a magnetic disk drive. In the present embodiment, the depth d1 of the shallowly grooved surface from the air bearing surface is about 200 nm while the depth d2 of the deeply grooved surface from the air bearing surface is about 1300 nm. The inflow side shallowly grooved surface 4a is constructed such that a length thereof from an inflow end to each of the inflow side air bearing surfaces 2a and 2b becomes longer on both sides of the slider.
When the magnetic head slider in the present embodiment is made to face a magnetic disk, the arrangement of the air bearing shallowly grooved surface 4a and the air bearing surfaces 2a and 2b causes a lifting force to be generated by the effect of the air bearing, where an air stream occurring as a result of rotation of the magnetic disk is compressed. The air stream expands, on the other hand, at the deeply grooved surface 5, and a negative pressure is generated. When this force generated by the air bearing balances a suspension load applied by a suspension, not shown, for supporting the magnetic head slider, the magnetic head slider flies. The flying height is 15 nm or less at a portion of the magnetic head 3.
In the magnetic head slider in the present embodiment, a lifting force (i.e., a load) generated by the air bearing can be remarkably increased by making the slider length more than that of the compact slider in the prior art.
The magnetic head slider flies through the balance between the aforementioned lifting force and the suspension load applied by the suspension, not shown. Accordingly, as the lifting force can be made greater, the suspension load can be further increased. The shock resistance of a magnetic disk drive during operation depends upon the condition of the suspension load for preventing the slider from moving away above the magnetic disk due to the force generated by acceleration applied from the outside, that is, the relationship between the acceleration α applied from the outside, a mass m and the suspension load W expressed by the following inequality: W>mα. An increase in suspension load with a slider of the same size proportionally enhances the shock resistance. Accordingly, the shock resistance of the magnetic head slider in the first embodiment according to the present invention can be enhanced by the increase in load (about 1.9 times) as compared with the conventional level.
The lifting force (i.e., the load) generated by the air bearing is substantially proportional to a disk speed. As a consequence, the magnetic head slider in the above-described embodiment exhibits a great effect in a disk drive having a small disk diameter and a low disk speed, which may be a disk drive having a diameter of 45.7 mm (1.8 in.) or less and a low disk speed.
Next, an explanation will be made of a pitch down preventing effect in reference to
In the above-described embodiment, the generated lifting force Fair becomes great by setting the ratio Lx/Ly to 1.8 owing to the increased slider length, and accordingly, the suspension load W also becomes great. Furthermore, the distance x1 from the inflow end to the pivot position also becomes great. As a consequence, it is possible to prevent the pitch down, which has been experienced in the compact slider shown in
In addition, the area of the air bearing surface on the inflow side can be enlarged by increasing the slider length, and therefore, the flying height on the inflow side can be satisfactorily increased. Consequently, it is possible to prevent any pitch down due to a decrease in flying height on the inflow side when a servo signal is written.
Moreover, since the slider width is set to 0.7 mm and the slider height is set to 0.23 mm in the above-described embodiment, the number of sliders to be taken from one wafer becomes about twice in comparison with the conventional slider having a width of 1 mm and a height of 0.3 mm. Thus, an inexpensive slider is provided in which the problems experienced in the prior art have been solved. Additionally, the number of sliders to be taken from one wafer can be further increased by decreasing the slider height Lz.
The inflow side air bearing surfaces 2a and 2b are connected to each other via the connection air bearing surface 7 in the second embodiment according to the present invention. This arrangement allows the lifting force produced at this portion to be greatly increased. The length of the connection air bearing surface 7 may be made shorter than that of each of the inflow side air bearing surfaces 2a and 2b. This enables peaks of a positive pressure to be distributed on both sides, thus ensuring an air bearing stiffness in a lateral direction. Moreover, since the connection between the air bearing surfaces can increase the expansion of air to the deeply grooved surface 5, the negative pressure can be made larger, and further, the slider can stably fly at a low flying height. The slider in the present embodiment is particularly suitable for a small-diameter magnetic disk of a low disk speed. Here, a depth d1 of a shallow groove is set to about 160 nm, and further, a depth d2 of a deep groove is set to about 900 nm. In the present embodiment, the generated lifting force becomes about 1.3 times that in the prior art, thereby producing the same effect as that in the first embodiment.
Furthermore, inflow end pads 12, each having the same height as that of the air bearing surface, are disposed on both sides of the air inflow end. The pad formed by dry etching has a smooth corner. Consequently, in the case where the inflow end of the slider is brought into contact with the disk due to the pitch down, the inflow end pad is brought into contact therewith. Therefore, a contact area becomes smaller with a soft contact, thereby reducing damage to the disk. Moreover, the inflow side of the slider may be brought into contact with a medium. In this case, since a clearance is defined by a depth of the shallow groove and the air flows through the clearance, the stable flying can be quickly recovered, thus preventing any pitch down.
It is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims alone with their full scope of equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-345532 | Nov 2004 | JP | national |
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| 2003-123422 | Apr 2003 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20060114612 A1 | Jun 2006 | US |
