Pseudo contact type negative pressure air bearing slider
A negative pressure air bearing slider includes a slider body for flying above a surface of a recording disc during relative rotation of the recording disc. First and second projections extend from a lead portion of a principal surface of the slider body to define first and second air bearing surfaces, respectively, the first and second air bearing surfaces being spaced apart from each other in the lateral direction of said slider body. A third U-shaped projection extends from the principal surface and includes a curved front wall portion at least partially located between the first and second projections and first and second side wall portions extending from opposite ends of the curved front wall portion to a rear portion of the principal surface so as to define a rounded negative pressure cavity therein. A fourth projection extends from the rear portion of the principal surface of the slider body at a position centrally located in the lateral direction of the slider body, and a transducer is mounted on a rear edge of the third projection so as to establish pseudo contact with the disc surface while the slider body is flying above the disc surface.
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This is a continuation of co-pending Ser. No. 09/892,790 filed on the 28th of Jun. 2001, which is a reissue application of Ser. No. 08/915,342 which was issued as U.S. Pat. No. 5,917,679 on the 29th of Jun. 1999.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a magnetic disk drive device, and in particular, to a pseudo contact type negative pressure air bearing slider for a transducer head assembly of a magnetic disk drive device.
2. Description of the Related Art
Transducer head assemblies have been designed to literally fly over a rapidly rotating disc, and include an air bearing slider for carrying a magnetic transducer proximate a rapidly rotating disc. The transducer, in the case of pseudo contact type sliders, is generally a thin-film head.
Computer disk drive technology evolution has focused on improvements in “areal density”, or the number of bits of information that can be stored in a given space on a magnetic disk. Over the last decade, the majority of progress has been gained through miniaturization of the recording heads and improving the magnetic efficiency of the write/read elements in the heads, and similar improvements in the magnetic and physical properties of the disks.
As suggested above, disk drives contain a plurality of recording heads that “fly” over rotating disks. The magnetic recording efficiency is a function of many physical characteristics of the heads and disks, the most significant of which is the spacing between the rotating disk surface and the recording head “pole” elements. The most straightforward method for manufacturers to improve areal density has been to reduce the spacing between the head disk, without sacrificing the long term reliability of the disk drive.
Across the previous disk drive industry product offerings, head-disk spacing had steadily decreased from several micro-inches to less than two micro-inches, until there came a point that further increases in areal density required the head to essentially touch the disk during flying. A new class of so-called “pseudo-contact” heads were developed in which the rear portion of the head, where the transducer poles are located, is in constant contact with the disk surface. Various design characteristics were developed to minimize friction and wear between the disk and head, and such “pseudo-contact” designs have proven to be as reliable over the long-term as the non-contact designs.
In magnetic disk technologies, it is generally desired to achieve higher data recording densities without a substantial change in form factor. In the context of the air bearing slider, increased recording densities are obtainable by maintaining the flying height, pitch angle and roll angle constant over the whole disk surface, to thereby enhance floating stability and contact start stop (CSS) reliability. In the case of the pseudo contact type slider, the “flying height” of the slider in effect refers to the pressure (or lack of pressure) applied to the disk surface by the assembly, and in particular, by the thin film transducer. Ideally, the slider should fly at a height in which the transducer makes pseudo contact with the disk surface at minimum pressure.
On the one hand, the magnetic head must fly at a sufficient height to avoid frictionally related problems caused by excessive physical contact during data communication between the magnetic head and the rapidly rotating disk. On the other hand, the head should be made to fly as low as possible to obtain the highest possible recording densities. As the magnetic head is fixed to the slider mechanism, the disk recording density increases as the flying height of the slider decreases. Accordingly, it is preferred that the slider fly as close as possible to the disk surface. A constant flying height is preferably maintained, regardless of variations in tangential velocity during flying, cross movements of the slider during data search operations, and changes in skew angle in the case of rotary type actuators.
To achieve stable flying characteristics, the slider should also fly at a pitch angle that falls within a safe range of a predetermined value. The pitch angle is defined as the tilt angle between the principal plane of the slider in the tangential direction of the rotating disc and the principal plane of the disc surface. The pitch angle is positive in the normal case in which the flying height of the rear portion of the slider is lower than that of the front portion of the slider. A transducer is generally situated at the lowest position of the rear portion of the slider for maximizing recording data capacity. If the designed pitch angle is too small, the possibility exists that a disturbance will cause the front end of the slider to dip down such that a negative pitch ensues resulting in a collision with the rapidly rotating disk. On the other hand, if the designed pitch angle is too large, the air stiffness needed for stable flying can be disadvantageously reduced. Therefore, to maintain stability while avoiding the situation of a negative pitch angle, the slider should be configured such that the pitch angle can be controlled to fall within an optimum value range. Another factor to consider regarding pitch angle is the general tendency for the pitch angle to increase with skew angle increases as the slider is positioned in a radially outward direction over the disc surface. Thus, the pitch angle should fall within the safe range regardless of skew angle variations.
Differing hydrodynamic forces support the inner and outer air bearing surface (ABS) rails of the slider, and resulting variations in side leakage air flow with skew angle changes can generate roll angle variations. Here, the inner and outer rails refer to those ABS rails of the slider positioned toward the inner periphery and outer periphery of the disc, respectively. Also, roll angle is defined as the tilt angle between the principal plane of the slider in the radial direction of the disc and the principal plane of the disc surface. As the transducer is usually centrally located on the rear slider edge in the case of pseudo contact slider, optimum performance is obtained by avoiding roll angle over the entire disk surface area.
The conventional slider of this type suffers a drawback in that the flying height, pitch angle and roll angle vary considerably according to the skew angle of the rotary type actuator, i.e., according to the radial position of the slider over the disc surface. For flying heights of 3.0 millionths of an inch and greater, minor height and tilt fluctuations in the slider do not generally affect the read/write operations of the disk. However, current-day standards require flying heights below 2.0 millionths of an inch. At such small flying heights, even minor variations in flying height, pitch angle and roll angle can severely affect the reliability of the head read/write function of a hard disk drive.
An improved configuration aimed at countering flying height variations over the entire disc surface is the transverse pressure contour (TPC) slider, as described, for example, in U.S. Pat. No. 4,673,996. As shown in
In light of the above, to better realize a constant flying height and constant pitch and roll angles and to obtain an improve contact start stop (CSS) performance, most current air bearing sliders have adopted a negative pressure air bearing (NPAB) type of configuration with a variety of air bearing surface shape changes. A basic NPAB slider has the same structure of the slider shown in
Because of sub-ambient pressure of cavity 14c 15c, roll angle during a high skew condition can worsen, meaning that the NPAB slider of
In consideration of the above, it is an object of the present invention to provide a negative pressure air bearing slider for a hard disk drive in which the application of negative pressure is stable, and the accumulation of debris is minimized.
It is another object of the present invention to provide a negative pressure air bearing slider for a hard disk drive which can maintain a relatively constant flying height regardless of skew angle.
It is still another object of the present invention to provide a negative pressure air bearing slider for a hard disk drive in which roll angle variations are minimized, sufficient air stiffness is maintained, and a constant optimum pitch angle is held.
Accordingly, to achieve the above and other objects, there is provided according to the invention a negative pressure air bearing slider, comprising: a slider body for flying above a surface of a recording disc during relative rotation of the recording disc, the slider body having a principal surface for confronting the disc surface, said principal surface having a lead portion, a rear portion, a first side portion and a second side portion, wherein the lead portion is spaced upstream of the rear portion relative to a longitudinal direction of said slider body which is coincident with a tangential rotational direction of the recording disc, and wherein the first side portion is spaced from the second side portion relative to a lateral direction of said slider body; first and second projections extending from said lead portion of said principal surface of said main body to define first and second air bearing surfaces, respectively, wherein said first and second air bearing surfaces are spaced apart from each other in the lateral direction of said slider body; and a third U-shaped third projection extending from said principal surface and having a curved front wall portion at least partially located between said first and second projections and curved first and second side wall portions extending from opposite ends of said curved front wall portion to said rear portion of said principal surface so as to define a rounded negative pressure cavity therein, said curved front wall portion and said first and second curved side wall portions being spaced apart from said first and second projections, wherein the first and second curved side wall portions respectively extend along said first and second side portions of said principal surface and define third and fourth air bearing surfaces located at said rear portion of said principal surface and space spaced apart from each other relative to the radial direction of said slider body; a fourth projection extending from said rear portion of said principal surface of said slider body at a position centrally located in the lateral direction of said slider body; and a transducer mounted on a rear edge of said third projection so as to establish pseudo contact with the disc surface while said slider body is flying above said disc surface.
The above objects and advantages of the present invention will become more apparent from the detailed description of the preferred embodiments thereof with reference to the attached drawings, in which:
FIGS. 6(a) and 6(b) are plan views illustrating alternative cross rail configurations of the negative pressure slider for a hard disk drive according to the present invention;
As shown in
Trailing ABS 110c and 110d are provided at the rear surface portion of the slider body 100 adjacent a rear edge 123 thereof. These trailing ABS platforms 110c and 110d are symmetrically disposed on opposite sides of a central longitudinal axis L of the slider body 100 and are aligned with one another in a lateral direction of the slider body 100, and provide a positive lifting force at an air outlet between the slider body 100 and the disc surface (not shown). In operation, the front and rear ABS platforms 110a, 110b, 110c and 110d generate sufficient positive pressure to support the slider body 100 in a suspended state above a rotating disk of a hard disk drive.
In addition, as shown in
Additionally, a forwardmost portion 131 of the arcuate cross rail 130 may be generally aligned with the longitudinal axis L of the slider body 100 and positioned partially between the lead ABS platforms 110a, 110b. However, the cross rail 130 is positioned a distance from a rear edge 133a 133b of each of the lead ABS platforms 110a, 110b to form a pair of wide passage 135a, 135b therebetween. The wide passages 135a, 135b coact with a wide space 135c extending from the lead edge 121 and interposed between the lead ABS platforms 110a, 110b and generally aligned with the longitudinal axis L, to form a wide air flow channel 135 that terminates along the sides of the slider body 100. The configuration of the air flow channel 135 enhances the stability of the slider 100, particularly as the skew angle of air flowing past the slider body 100 increases. The configuration of the air flow channel 135 and cross rail 130 provide further advantages to be discussed more thoroughly hereinafter. It is noted that the arcuate cross rail 130 should be made as thin as possible to avoid adverse influence on the positive pressure areas created by the four separate and distinct air bearing surfaces 110a, 110b, 110c, 110d, while simultaneously providing a stable and centrally located negative pressure area 150.
The negative pressure cavity 150 functions to provide a downward pulling action on the slider body 100, which in turn creates a gram load equivalent effect that enhances stability. The rounded configuration of both the negative pressure cavity 150 and the cross rail 130 reduces the skew angle dependency on the magnitude of gram load equivalency. Since the negative pressure cavity is rounded, angular variations in the direction of air flow resulting from skew angle changes do not substantially alter the action of the negative pressure cavity 150. This results in reduced flying characteristic (flying height and roll angle) variations as the slider is positioned at different diameters along the disc surface. Skew angle related variations are further minimized by the four stable positive lifting forces positioned at each corner around the centrally located negative pressure cavity.
Another advantage of the arcuate configuration of the cross rail 130 resides in the fact that contaminates will have less of a tendency to accumulate against the front wall of the cross rail. That is, contaminates will instead tend to travel along the arcuate front wall and exit off the side of the slider body between the gaps formed by the front corner ABS projections. This also enhances read/write performance of the slider 100 over the long run.
Reference numeral 180 of
As shown in
Referring again to
Further modifications of the invention will now be described with reference to
Characteristics of the negative pressure cavity 150 may in some instances retard the take-off of the slider during an initial operational phase. This problem is largely overcome by the provision of a shallow recessed step 131 on the cross rail 130 as shown in FIG. 9. The recessed step 131 allows sufficient air flow through the negative pressure cavity 150 to prevent delay in the slider take-off period. This recessed step can also reduce debris accumulation on the cross rail 130.
As an alternative to the recess 131, a gap 132 in the cross rail 130 may instead be provided as shown in FIG. 10. This configuration provides similar results of relieving the negative pressure during take-off and reducing debris accumulation.
The recess 131 and the gap 132 of
Referring once again to
As described above, the NPAB type slider of the invention provides a relatively constant flying height, minimized roll and pitch angle variations, and excellent reliability. During operation, most of the positive pressure is generated at the four corner ABS's, and since the cross rail has a curved configuration, negative pressure is generated at a geometrical central area. This results in stable flying characteristics without substantial variations in the flying height and pitch and roll angles throughout the entire data range. Additionally, the arcuate configuration of the cross rail minimizes contaminant accumulation.
While the present invention has been described in terms of the embodiments described above, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims and their equivalents.
Claims
1. A negative pressure air bearing slider, comprising:
- a slider body for flying above a surface of a recording disc during relative rotation of the disc, the slider body having a principal surface for confronting the surface of the disc, said principal surface having a lead portion, a rear portion, a first side portion and a second side portion, wherein the lead portion is spaced upstream of the rear portion relative to a longitudinal direction of said slider body which is coincident with a tangential rotational direction of the recording disc, and wherein the first side portion is spaced from the second side portion relative to a lateral direction of said slider body;
- first and second projections extending from said lead portion of said principal surface of said slider body to define first and second air bearing surfaces, said first and second air bearing surfaces spaced apart from each other in the lateral direction of said slider body;
- a U-shaped projection extending from said principal surface of said slider body, said U-shaped projection including an arcuate front wall portion at least partially located between said first and second air bearing surfaces, said U-shaped projection further including first and second side wall portions extending from opposite ends of said arcuate front wall rearwardly toward said rear portion and outwardly toward said first and second side portions of said principal surface for defining a negative pressure cavity therein, said first and second wall portions terminating at said rear portion of said principle principal surface of said slider body for defining third and fourth air bearing surfaces, said third and fourth air bearing surfaces spaced apart from each other along said lateral direction of said slider body and spaced apart from said first and second air bearing surfaces along said longitudinal direction of said slider body; a fourth projection extending from said rear portion of said principal surface of said slider body, said fourth projection interposed between said third and fourth air bearing surfaces and generally aligned with said longitudinal direction of said slider body; and
- a transducer mounted on a rear edge of said fourth projection for establishing pseudo contact with the disc surface while said slider body is flying above said disc surface.
2. The negative pressure air bearing slider as claimed in claim 1, wherein said U-shaped projection is axisymmetrical about a longitudinal axis of said slider body.
3. The negative pressure air bearing slider as claimed in claim 2, wherein said first and said second air bearing surfaces are symmetric about said longitudinal axis of said slider body.
4. The negative pressure air bearing slider as claimed in claim 2, wherein said first and said second air bearing surfaces are respectively longitudinally aligned with said third and fourth air bearing surfaces, and wherein said negative pressure cavity is centrally located between said air bearing surfaces.
5. The negative pressure air bearing slider as claimed in claim 1, wherein each of said first and said second air bearing surfaces include a tapered surface portion, the tapered surface portion tapering from each air bearing surface toward a lead edge of said slider body.
6. The negative pressure air bearing slider as claimed in claim 1, wherein each of said first and said second air bearing surfaces include a stepped down surface portion, the stepped down surface portion extending from each air bearing surface to a lead edge of said slider body.
7. The negative pressure air bearing slider as claimed in claim 1, wherein an interface region between said arcuate front wall portion and said first side wall portion includes a first stepped down surface portion extending between said third air bearing surface and an inner edge of said slider body, and wherein an interface region between said arcuate front wall portion and said second side wall portion includes a second stepped down surface portion extending between said fourth air bearing surface and an outer edge of said slider body.
8. The negative pressure air bearing slider as claimed in claim 1, wherein an interface region between said arcuate front wall portion and said first side wall portion includes a first stepped down surface portion extending between said third air bearing surface and said negative pressure cavity, and wherein an interface region between said arcuate front wall portion and said second side wall portion includes a second stepped down surface portion extending between said fourth air bearing surface and said negative pressure cavity.
9. The negative pressure air bearing slider as claimed in claim 8, wherein the interface region between said arcuate front wall portion and said first side wall portion further includes a third stepped down surface portion extending between said third air bearing surface and said negative pressure cavity, and wherein the interface region between said arcuate front wall portion and said second side wall portion further includes a fourth stepped down surface portion extending between said fourth air bearing surface and said negative pressure cavity.
10. The negative pressure air bearing slider as claimed in claim 1, wherein an elongated groove is provided in said arcuate front wall portion, said groove extending between said first and second side wall portions.
11. The negative pressure air bearing slider as claimed in claim 1, wherein an opening is provided in said arcuate front wall portion, said opening located between said first and second side wall portions and extending to said principle principal surface of said slider body.
12. The negative pressure air bearing slider as claimed in claim 11, wherein said opening is offset from a longitudinal axis of said slider body.
13. The negative pressure air bearing slider as claimed in claim 11, wherein said opening is symmetrical about a longitudinal axis of said slider body.
14. The negative pressure air bearing slider as claimed in claim 10, wherein said elongated groove in said arcuate front wall portion is symmetrical about a longitudinal axis of said slider body.
15. The negative pressure air bearing slider as claimed in claim 10, wherein said elongated groove in said arcuate front wall portion is offset about a longitudinal axis of said slider body.
16. A negative pressure air bearing slider, comprising:
- a slider body for flying above a surface of a recording disc during relative rotation of the disc, the slider body having a principal surface facing the surface of the disc, said slider having a lead edge, a rear edge, a first side edge and a second side edge, wherein the lead edge is spaced upstream of the rear edge along a longitudinal axis of said slider body, the longitudinal axis coincident with a tangential rotational direction of the recording disc, and wherein the first side edge is spaced from the second side edge along a latitudinal axis of said slider body;
- first and second projections extending from a lead portion of said principal surface adjacent to said lead edge to provide first and second air bearing surfaces, said first and second air bearing surfaces spaced apart from each other along said latitudinal axis and located proximal to said first and second side edges of said slider body such that a gap is provided therebetween;
- a U-shaped projection extending from said principal surface of said slider body, said U-shaped projection including an arcuate front wall and first and second side walls extending from each end of said front wall, each of said side walls extending rearwardly toward said rear portion and outwardly toward an adjacent side edge of said slider body for defining a negative pressure cavity therein, a forwardmost portion of said arcuate front wall located at least partially between said first and second air bearing surfaces such that first and second passages are formed between the arcuate front wall and a rear edge of said first and second air bearing surfaces, said passages communicating with said gap to provide a flow path that extends from said lead portion and terminates along said side edges prior to reaching a rear portion of said slider body adjacent to said rear edge thereof, said first and second wall portions terminating at said rear portion of said slider body for defining third and fourth air bearing surfaces spaced apart along said latitudinal axis and located proximal to said first and second side edges of said slider body, the air bearing surfaces positioned about on said principle principal surface of said slider body such that four separate and distinct positive pressure areas are provided when said slider body is flying above said rotating disc; and
- a fourth projection extending from said rear portion of said slider body, said fourth projection generally aligned with said longitudinal axis of said slider body, the fourth projection including a transducer mounted on a rear edge thereof for establishing pseudo contact with the disc surface while said slider body is flying above said disc.
17. The negative pressure air bearing slider of claim 16 wherein said forward most portion of said arcuate front wall is aligned generally with said longitudinal axis of said slider body.
18. The negative pressure air bearing slider of claim 16 wherein said negative pressure cavity is generally rounded.
19. The negative pressure air bearing slider of claim 16 wherein each of the passages of said flow path extend tangentially to said longitudinal axis of said slider body.
20. The negative pressure air bearing slider of claim 16 wherein each of the passages and said gap of said flow path coact to provide a wide flow path.
Type: Grant
Filed: Dec 9, 2002
Date of Patent: Mar 7, 2006
Assignee: SamSung Electronics Co., Ltd. (Suwon-si)
Inventors: Ki-Ook Park (Seoul), In-Eung Kim (Seoul), In-Seop Jeong (Seoul), Tae-Seok Park (Suwan)
Primary Examiner: Robert S. Tupper
Attorney: Robert E. Bushnell, Esq.
Application Number: 10/314,937
International Classification: G11B 5/60 (20060101);