Patent Application
20200090692
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2018-171476, filed Sep. 13, 2018, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a magnetic head and a magnetic disk device including the same.
Hard disk drive (HDD) and the like include, as a magnetic disk device, a magnetic disk provided therewith rotatably, and a magnetic head configured to write/read data to/from the magnetic disk. In HDD in the operation state, the magnetic head flies on air current produced by the rotation of the magnetic disk and faces the surface of the magnetic disk with a slight gap therebetween.
When an external impact is applied to HDD, the impact may cause a concave or convex deformation in the inner periphery or the outer periphery of the magnetic disk. The deformation of the magnetic disk changes the flying state of the magnetic head, and the magnetic head may contact the magnetic disk surface. In that case, the magnetic disk and/or magnetic head may be damaged.
Various embodiments will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment, a magnetic head comprises a slider including an air bearing surface with a pair of side edges, a pair of side surfaces disposed along the pair of side edges of the air bearing surface, a leading-side end surface, and a trailing-side end surface; and a head portion provided in the slider to perform data processing. The slider comprises a leading step provided at a leading-side end of the air bearing surface, a trailing step provided at a trailing-side end of the air bearing surface and including the head portion, a deep groove formed between the leading step and the trailing step to be opened to the air bearing surface and the pair of side surfaces, and a shallow groove provided in a center area between the pair of side edges in a region between the deep groove and the trailing step.
Note that the disclosure is an example, and the contents of the following description do not limit the scope of the invention. Variations which will easily be conceivable by a person having ordinary skill in the art are naturally encompassed within the scope of the invention. In the figures, dimensions of components may be depicted schematically as compared to actual models of the invention for easier understanding. Elements corresponding to each other between different figures will be referred to by the same reference number, and explanation considered redundant may be omitted.
As an example of the magnetic disk device, a hard disk drive (HDD) of a first embodiment will be explained.
As shown in
In the casing 10 are provided one or more magnetic disks 16 as disk-shaped recording media and a spindle motor 23 as a driver configured to support and drive the magnetic disks 16 therein. The magnetic disks 16 are coaxially engaged on a hub (which is not shown) of the spindle motor 23, clamped and fixed to the hub by a clamp spring 27. The magnetic disks 16 are rotated by the spindle motor 23 in the direction of arrow A at a certain rotation rate.
In the casing 10 are provided a plurality of magnetic heads 17 configured to write/read data to/from the magnetic disks 16 and a carriage assembly 22 configured to support the magnetic heads 17 to be movable with respect to the magnetic disk 16 therein. In the casing 10 are provided a voice coil motor (VCM) 24 configured to rotate and position the carriage assembly 22, lamp load mechanism 25 configured to maintain the magnetic heads 17 to an unload position which is apart from the magnetic disks 16 when the magnetic heads 17 moves to the outermost periphery of the magnetic disk 16, latch mechanism 26 configured to maintain the carriage assembly 22 in an evacuation position when an impact or the like is applied to the HDD, and substrate unit 21 including a conversion connector or the like.
A printed circuit board (which is not shown) is fixed to the outer surface of the bottom wall 12a of the base 12 with screws. A controller is formed in the printed circuit board. The controller controls the operation of the VCM 24 and magnetic head 17 via a substrate unit 21 and controls the operation of the spindle motor 23.
The carriage assembly 22 comprises a bearing portion (main body block) rotatably supported on the base 12, a plurality of arms 28 extending from the bearing portion, and a head gimbal assembly 30 extending from each arm 28. Each head gimbal assembly 30 includes a slender plate spring-shaped suspension 34, a flexure 41 disposed on the suspension 34 as a wiring member, and a magnetic head 17. The magnetic head 17 is supported at the dispail end of the suspension 34 via a gimbal portion 36 of the flexure 41.
As shown in
Now, the structure of the magnetic head 17 will be explained.
As shown in
A longitudinal direction of the ABS 40 is defined as a first direction X, and a width direction perpendicular to the first direction X is defined as a second direction Y. A center axis line D of the magnetic head 17 extends in the first direction X passing through the center of the magnetic head 17. In this embodiment, the slider 31 has a length L1 in the first direction X of 1.25 mm or less, for example, 1.235 mm, a width W1 in the second direction Y of 1.0 mm or less, for example 0.7 mm, and a thickness T1 of 0.15 to 0.3 mm, and is configured as a so-called Pemto-slider.
As shown in
A substantially rectangular leading step 52 is A substantially rectangular leading step 52 is formed on the leading-side end portion of the ABS 40. The leading step 52 protrudes from the bottom surface of the deep groove 50 and is positioned on an inflow side of the deep groove 50 with respect to the air flow B.
In order to maintain a pitch angle of the magnetic head 17, a leading pad (inflow-side pressure generating surface) 53 supporting the slider 31 by an air film protrudes from the leading step 52. The leading pad 53 is formed in a letter M with a plurality of openings toward the inflow-side. The upper surface of the leading pad 53 forms the uppermost surface of the slider 31 and is a part of the ABS 40. A leading groove 55 is formed in a position slightly shifted from the inflow-end of the leading step 52 toward the outflow-side.
As shown in
In the ABS 40, a rib-shaped intermediate cross rail 56, pair of side pads 58, and pair of center rail (center pad) 68 are formed to surround the negative pressure cavity 54. The intermediate cross rail 56 is positioned between the deep groove 50 and the negative pressure cavity 54 and extends between the side edges of the ABS 40 in the second direction Y. The intermediate cross rail 56 protrudes from a bottom surface of the negative pressure cavity 54 and is positioned on the inflow-side of the negative pressure cavity 54 with respect to the air flow B.
The pair of side pads 58 are formed along each side edge of the ABS 40, and extend in the outflow end side of the ABS 40 from the intermediate cross rail 56, bend to the side edge side, and further bend to the leading side to extend in the leading side along the side edge. The side pads 58 protrude from the bottom surface of the negative pressure cavity 54.
A pair of skirts 60 are formed along each side edge (side surface 42c) and each extend to the proximity of the trailing-side end surface 42b of the ABS 40 from the side pads 58 in the first direction X. Each skirt 60 protrudes from the bottom surface of the negative pressure cavity 54 and is formed to be lowered as compared to the side pads 58.
The intermediate cross rail 56, the pair of side pads 58, and the pair of skirts 60 are, as a whole, formed substantially as a letter U which is closed on an upstream side and is open toward a downstream side. The intermediate cross rail 56, side pads 58, and skirts 60 define the negative pressure cavity 54.
As shown in
The trailing pad 63 is provided on the trailing step 62 and spaced with a gap from the outflow-side end surface of the trailing step 62, here, from the outflow-side end surface 42b of the slider 31. The trailing pad 63 is formed substantially at the same height as the leading pad 53, intermediate cross rail 56, and side pad 58, and forms the uppermost surface of the slider 31 as a part of the ABS 40.
The head portion 33 of the magnetic head 17 includes a recording element 65 and a reading element 66 for recording/reading information to/from the magnetic disk 16. The recording element 65 and the reading element 66 are embedded in a downstream-side end portion of the slider 31 in the direction of the air flow B, here, in the trailing step 62. Tip end portions of the recording element 65 and the reading element 66 are exposed to the ABS 40 at the position of the trailing pad 63.
The ABS 40 of the slider 31 includes a pair of elongated center rails 68 extending from the intermediate cross rail 56 to the trailing step 62 in the first direction X. The center rails 68 are positioned in the both sides of the center axis line D of the slider 31 and are opposed to each other with a gap therebetween in the second direction Y. The center rail 68 is disposed between the deep groove 50 and the trailing step 62 and in a center area of a pair of side edges of the slider 31 (center part in the width direction). The center rail 68 is formed to have a height from the bottom surface of the negative pressure cavity which is the same as the heights of the intermediate cross rail 56 and the trailing pad 63. A guide groove 76 is formed between the center rails 68 to introduce the air current to the trailing step 62 and the trailing pad 63. The guide groove 76 is formed along the center axis line D, passes the deep groove 50, and extends to the leading step 52.
As shown in
Note that the depth DG of the shallow groove 70 may be structured to have varied depths in the longitudinal direction thereof instead of having a constant depth.
The above-described leading step 52 forms a step portion of the slider 31 in the inflow side. Furthermore, the intermediate cross rail 56, side pads 58, and trailing step 62 form a step portion of the slider 31 in the outflow side. The deep groove 50 is disposed between the inflow side step portion and the outflow side step portion.
In contrast, as described above, in the magnetic head 17 of the present embodiment, the shallow groove 70 is formed in the center rail 68 of the slider 31, and a gap between the surface of the magnetic disk 16 and the slider 31 can be widened by the depth of the shallow groove 70. Thus, even if the magnetic disk 16 is deformed, contact, collision, or the like of the slider 31 and the magnetic disk 16 can be prevented. Note that, if the depth DG of the shallow groove 70 is 2 to 30 nm, the shallow groove 70 does not greatly affect the hovering position of the slider 31.
As can be understood from the above, in the present embodiment, a magnetic head which less contacts a recording medium to increase the reliability and a magnetic disk device including the magnetic head can be achieved.
The slider may not include an ABS 40 with a center rail. The shallow groove 70 may be disposed in an area between the center part of the slider and the trailing pad instead of the center rail.
Now, a magnetic head of another embodiment will be explained. Note that, in the following embodiment, elements corresponding to those of the first embodiment will be referred to by the same reference numbers and the detailed description may be omitted or simplified while differences from the first embodiment will be mainly described.
The inclined surface 70A extends from the intermediate cross rail 56 to a distal end of the trailing step 62, i.e., a portion near the recording element 65 through the center rails 68 and the side pads 58. The inclined surface 70A is laid over the entire width of the slider 31. The inclined surface 70A is inclined toward the rear surface side of the slider 31 from the intermediate cross rail 56 to the trailing step 62.
In the above-described structure, a gap between the surface of the magnetic disk 16 and the slider 31 can be widened by the amount grated by the polishing to form the inclined surface 70A, and a contact and collision of the slider 31 and the magnetic disk 16 can be prevented. When the inclined surface 70A is formed by the polishing to the depth of 2 to 30 nm, the flying position of the slider 31 is not greatly affected.
If a magnetic disk 16 is deformed as a concave with respect to a magnetic head 17 caused by an external impact or the like, an equivalent crown is added to the deformation of the magnetic disk, and side edges of the slider 31, that is, the proximity of side pads 58 becomes closest to the magnetic disk surface, and thus, the proximity of the side pads 58 flies the least. Thus, in the third embodiment, as shown in
In the above-described structure, the shallow groove 74 is provided with the side pad 58 to increase a gap between the surface of the magnetic disk 16 and the slider 31 by the depth of the shallow groove 74. Thus, even if the magnetic disk 16 is deformed in a concaved shape, a contact and collision of the slider 31 and the magnetic disk 16 can be prevented. If the depth of the shallow groove 74 is 2 to 30 nm, the shallow groove 74 does not greatly affect the flying position of the slider 31.
Note that, in the example depicted, the shallow groove 70 is provided with the center rail 68, however, no limitation is intended thereby. The shallow groove 70 of the center rail 68 may be omitted, and the shallow groove 74 may be provided with each side pad 58 alone. In that case, the impact resistance of the magnetic head can be improved.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
For example, the slider of the magnetic head is not limited to a Pemto-slider, and it may be a pico-slider, femto-slider, or greater-size slider. The shape, size, and the like of the trailing step, trailing pad, and other parts in the slider may be changed arbitrarily. In the disk drive, the magnetic disk is not limited to a 3.5 inch type. The number of magnetic disks is not limited to two, and it may be one or three or more, and the number of the magnetic heads may be increased or decreased to conform to the number of the magnetic disks.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-171476 | Sep 2018 | JP | national |
