Slider having recessed corner features

One aspect of the present invention relates to a slider having a slider body. The slider body includes a bearing surface defining a bearing surface plane, a leading edge, a trailing edge, first side edge, a second side edge and at least one corner. A corner feature is positioned proximate the at least one corner. The corner feature includes a first portion oriented in a first direction and a second portion oriented in a second direction that is different then the first direction. At least one of the first direction and the second direction is toward the trailing edge and is oblique to the bearing surface plane.

BACKGROUND OF THE INVENTION

The present invention relates to data storage systems and, more particularly, to a data storage system having a slider with features for reduced slider-media impact.

Data storage systems such as disc drives are well known in the industry. Such drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g. air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.

An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each disc head slider. The suspension includes a load beam and a gimbal. The load beam provides a load force which forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc.

The slider includes a hydrodynamic (e.g. air) bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to fly above or in close proximity to the disc surface.

In ramp load-unload applications, the disc drive further includes a ramp positioned at an outer diameter of the disc for engaging the suspension. When the disc drive is powered down, the actuator mechanism moves the suspension radially outward until the suspension engages the ramp, causing the slider to lift off of the disc surface. In the case of a slider having a subambient pressure cavity, the suspension and slider must overcome the suction force developed by the subambient pressure cavity (which tends to pull the slider toward the disc) in order to lift the slider up the ramp. During power-up, the disc is accelerated to its normal operating velocity and then the actuator mechanism moves the suspension radially inward such that the suspension disengages the ramp allowing the slider to become loaded on to the disc surface.

Using a ramp to load and unload the suspension relative to the disc surface has been regarded as an attractive alternative to “contact start/stop” technology in which the slider lands and takes-off from a dedicated zone on the disc surface. The ramp load-unload technique can be used for solving tribological problems associated with lower fly heights and for meeting severe requirements of non-operational shock performance. However, this technique introduces an array of other challenges, such as possible severe head-media impact during loading and unloading operations.

Under nominal conditions, advanced air bearings (AABs) can be designed to avoid head-media contact during load and unload. Manufacturing of actual parts, however, introduces deviation from nominal conditions, which can result in larger susceptibility of impact during load-unload operations. Among the numerous dimensions and geometrical features to be controlled during manufacturing, pitch static attitude (PSA) and roll static attitude (RSA) are the most critical parameters for load-unload applications. PSA is the angle formed between the slider and the suspension in a direction parallel to the suspension's axis of symmetry when no air bearing is formed (i.e., in a “static” state). RSA is the angle formed between the slider and the suspension in a direction perpendicular to the suspension's axis of symmetry.

Since PSA and RSA have an influence on the pitch and roll attitude of the slider during flight, manufacturing tolerances that result in a non-optimal PSA or RSA cause the slider to tilt with respect to the radial motion of the suspension during loading and unloading operations. Under these conditions, it is possible that the corners of the slider can become close enough to the media to induce light contact or severe impact. When the slider is being loaded onto the disc, a corner or edge of the slider can contact the disc before an air bearing has been developed. During unloading, imbalances between the suction force and the lift force can also cause the slider to contact the disc. This contact can cause damage to stored data, thermal asperities and permanent physical damage to the slider and disc surfaces.

Similarly, in a contact-start-stop system, a corner of the slider can contact the disc in response to shock forces applied to the disc drive or other events that cause a variation in the flying height of the slider. Any such contact leads to wear of the slider and the recording surface and is potentially catastrophic.

One method of reducing damage caused by contact between the slider and the disc is to provide landing pads on the slider, which have a smoother contact surface than the etched surfaces on the slider body. The landing pads can be below or within the pressurization plane of the bearing surface. Another method of reducing damage caused by contact between the slider and the disc is to provide the bearing surface with at least one rounded corner. Also, the non-bearing surfaces can be provided with at least one rounded edge or a deeply recessed corner. As a result, the disc surface is less likely to be damaged when hit by the rounded corner or edge than a sharp corner or edge.

However, strong contact can still occur with the above-mentioned methods due to inadequate pressurization at different PSA and RSA conditions. A slider is therefore desired that avoids or reduces contact with the disc surface during operational shock events and/or during load and unload operations.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a slider having a slider body. The slider body includes a bearing surface defining a bearing surface plane, a leading edge, a trailing edge, a first side edge, a second side edge and at least one corner. A corner feature is positioned proximate the at least one corner. The corner feature includes a first portion oriented in a first direction and a second portion oriented in a second direction that is different from the first direction. At least one of the first direction and the second direction is toward the trailing edge and is oblique to the bearing surface plane.

Another aspect of the present invention relates to a slider body having a leading edge, trailing edge, a first side edge, a second side edge and first and second corners at opposing ends of the trailing edge. First and second corner features are positioned proximate the first and second corners and first and second side edges, respectively. The first and second corner features each define an opening such that fluid flow from the trailing edge can enter each opening.

A further aspect of the present invention relates to a slider body. The slider body includes a leading edge, a trailing edge, first and second side edges and first and second corners at opposing ends of the trailing edge. Fluid pressure is generated at the first and second corners to prevent impact between the slider body and the storage medium.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1is a perspective view of a disc drive100in which the present invention is useful. Disc drive100can be configured as a traditional magnetic disc drive, a magneto-optical disc drive or an optical disc drive, for example. Disc drive100includes a housing with a base102and a top cover (not shown). Disc drive100further includes a disc pack106, which is mounted on a spindle motor (not shown) by a disc clamp108. Disc pack106includes a plurality of individual discs107, which are mounted for co-rotation about central axis109. Each disc surface has an associated slider110, which is mounted to disc drive100and carries a read/write head for communication with the disc surface. It is worth noting that although a plurality of individual discs is illustrated inFIG. 1, the present invention can also be applied to disc drives having a single disc.

In the example shown inFIG. 1, sliders110are supported by suspensions112which are in turn attached to track accessing arms114of an actuator116. The actuator shown inFIG. 1is of the type known as a rotary moving coil actuator and includes a voice coil motor (VCM), shown generally at118. Voice coil motor118rotates actuator116with its attached sliders110about a pivot shaft120to position sliders110over a desired data track along a path122between a disc inner diameter124and a disc outer diameter126. Voice coil motor118operates under control of internal circuitry128. Other types of actuators can also be used, such as linear actuators.

As discussed in more detail below, slider110has a hydrodynamic (e.g., air) bearing that reduces the chance of head-media contact in ramp load-unload applications and in contact start-stop applications. In ramp load-unload applications, disc drive100includes a ramp130for each suspension112. Ramps130are positioned near disc outer diameter126. When disc drive100is powered-down, voice coil motor118rotates actuator116toward disc outer diameter126so that suspensions112engage the respective ramps130. Ramps130lift suspensions112so that sliders110are unloaded from the disc surface. During power-up, once discs107have accelerated to their operating rotation velocity, voice coil motor118rotates actuator116in a radially inward direction to disengage suspensions112from ramps130and thereby load sliders110onto the disc surfaces. When sliders110are loaded onto the disc surfaces, the ramp unloading process introduces a roll motion in the sliders. Depending upon the magnitude of the roll motion, the pitch static angle (PSA) of the suspension, and the roll static angle (RSA) of the suspension, it is possible that the tilt of a typical slider with respect to the radial load-unload motion of actuator116can cause the edges or corners of the slider to contact the disc surface. This contact can range from light contact to severe impact and can cause damage to stored data or permanent physical damage to the media. Sliders110have a bearing geometry that reduces the chances and severity of such contact.

FIG. 2is a bottom, perspective view of one of the sliders110ofFIG. 1, as viewed from the surface of disc107according to one embodiment of the present invention. The vertical dimensions of slider110are greatly exaggerated inFIG. 2for clarity. Slider110includes features and at least one bearing surface for generating a force to lift slider110above the surface of disc107. The at least one bearing surface defines a bearing surface plane, which provides a reference for other features and surfaces on slider110.

Slider110has a leading edge200, a trailing edge202, side edges204and206, and a lateral center line208. Elongated, raised side rails210and212are positioned along side edges204and206, respectively, and form bearing surfaces214and216, respectively. Rails210and212extend generally from leading slider edge200toward trailing slider edge202and terminate prior to trailing slider edge202. However, rails210and212can extend all the way to trailing slider edge202in alternative embodiments. Additionally, the rails illustrated herein are illustrative and other rail configurations can be used in accordance with embodiments of the present invention.

A cavity dam230extends between rails210and212, along leading slider edge200. Cavity dam230has a leading edge232and a trailing edge234. Cavity dam230and side rails210and212define a subambient pressure cavity (or “central recess”)236, which trails cavity dam230relative to a direction of air flow from the leading slider edge200toward trailing slider edge202. In one embodiment, central recess236is recessed from bearing surfaces214and216by 1 to 3 μm. Other depths can also be used. In addition, cavity dam230can be formed with a tapered leading edge in alternative embodiments, if desired.

A raised center pad or rail240is positioned along trailing slider edge202. In alternative embodiments, center pad240can be skewed or offset with respect to a center of the slider. Center pad240has a leading step surface241and a bearing surface242. Leading step surface241is generally parallel to and recessed from bearing surface242by a step depth of 0.1 to 0.5 μm, for example, for providing pressurization of bearing surface242from air flow venting from central recess236. Center rail240supports a read/write transducer244along trailing slider edge202. In alternative embodiments, transducer244can be positioned at other locations on slider110. However, when placed at or near trailing slider edge202, transducer244is located at the closest point on slider110to the surface of disc107(shown inFIG. 1) under most nominal operating conditions. With a positive pitch angle, trailing slider edge202is closer to the surface of disc107than leading slider edge200.

Rails210and212terminate prior to trailing slider edge202to allow slider110to roll about lateral center line208without risking contact between trailing rail edges and the disc surface at nominal roll angles. Therefore, the trailing edge of center pad240remains the closest location on slider110to the disc surface during flight at nominal roll angles, thereby improving read and write performance.

Slider110further includes recessed corner features270-273, which are positioned at and form part of corners280-283, respectively, of slider110. Recessed corner features270-273further reduce the chance of contact between slider110and the disc surface during ramp load and unload operations and in response to operating shock events. In the embodiment illustrated, recessed corner features270-273are recessed from bearing surfaces214and216by a depth that is greater than the depth of central recess236.

During ramp load and unload operations and during operational shock events, recessed corner surfaces270-273can delay contact between slider110and the surface of the disc at corners280-283by allowing greater roll angles about lateral center line208. The extra time allows slider110to reposition itself in order to develop the air bearing pressure needed to lift the slider away from the disc surface before contact occurs. Even if contact occurs, the overall impact with the disc surface is substantially reduced. In one embodiment, the sizes and shapes of recessed corner surfaces270-273are chosen to maximize the delay of contact at the pitch and roll attitudes at which contact is possible.

FIG. 3is a detailed view of corner280of slider110inFIG. 2. Recessed corner feature270is cup-shaped and includes recessed surfaces or portions290-293that define an opening such that fluid flow can enter the opening from trailing edge202and side edge206. Features271-273are similar to recessed feature270. As illustrated, each of the surfaces290-293has a different surface normal direction or orientation creating an overall cup shape. Additionally, each of the surfaces290-293is oblique to the bearing surface plane, which is defined by bearing surfaces214and216, for example. Recessed feature270generates pressurization over a large range of pitch static angles and roll static angles. An effective air bearing is generated on recessed feature270through the multi-plane surfaces in order to adapt to different pitch and roll attitude situations experienced during load/unload operations. As a result, the recessed feature270avoids and/or delays direct head-media contact and furthermore minimizes head-media impact while maximizing air bearing lift. Additionally, recessed feature270eliminates a sharp corner on the body of slider110and thus contact damage and particle generation is reduced in the event of contact between slider110and a disc surface. If desired, feature270can include a surface microstructure for lower contact friction force in the event of head-media impact. Moreover, recessed feature270has a greater depth than central recess236and thus has limited effect on the fluid pressure generated by the bearing surface on the slider body during operation of the disc drive.

It should further be noted that recessed feature270can include various shapes, sizes, etc. in accordance with the present invention. For example, the recessed feature270can include one or more arcuate or curved surfaces such as a spherical or conical shape to form a concave or convex surface with respect to a corner.FIGS. 9 and 10illustrate recessed-shaped features300and302, respectively, that have openings facing the trailing edge. Recessed-shaped feature300is a generally spherical shape while cup-shaped feature302is generally conically shaped. Features300and302both include a first portion oriented in a first direction and a second portion oriented in a second direction that is different from the first direction. Together, the first and second portions define an arcuate surface that develops air bearing pressure at the corner of a slider during ramp load and unload operations.

FIG. 4is a perspective view of a slider400according to an alternative embodiment of the present invention. The same reference numerals are used inFIG. 4as were used inFIGS. 2-3for the same or similar elements. Once again, the vertical dimensions inFIG. 4are exaggerated for clarity. Slider400includes recessed corner features401-404that form part of corners280-283, respectively. As illustrated inFIG. 5, exemplary corner feature404includes recessed surfaces410and411oblique to the bearing surface plane. Features401-403are similar to feature404. The surfaces410and411are illustrated as being parallel, but could be oriented with different surface normal directions. Feature401also includes a trench412positioned between surfaces410and411and recessed from the surfaces410and411. An additional trench413is connected to and orthogonally oriented with respect to trench412. Together, trench412and trench413define an opening such that fluid flow can enter the opening from the trailing edge202and side edge206. As slider400rolls towards a disc surface, air enters trench412, which provides pressure on surfaces410and411. This pressurization aids in preventing contact between slider400and a disc surface. If desired, trench412can have a variable depth in order to increase pressurization of surfaces410and411. Feature401can be made using gray scale photolithography by linking trenches412and413together.

FIG. 6is a perspective view of a slider600according to an alternative embodiment of the present invention. Slider600has a leading edge602, a trailing edge604and side edges606and608. A raised longitudinal wall610is positioned proximate leading edge604. Two longitudinally extending walls612and614extend from wall610towards trailing edge604and define a central recess616. Forward pads618and620are provided near side edges606and608, respectively. Pad618includes a leading step surface622and a trailing bearing surface624. Likewise, pad620includes a leading step surface626and a trailing bearing surface628. Slider600further includes lateral walls630and632extending from longitudinal walls612and614, respectively. An L-shaped trench634is formed by pad618, wall612and wall630. Likewise, an L-shaped trench636is formed by pad620, wall614and wall632. Step surfaces638and640extend from lateral walls630and632, respectively, toward trailing edge604. A center pad641forming a bearing surface642is provided proximate the center of trailing edge604. Step surfaces644and646are also formed on the center pad. Additionally, an oblique trailing surface650is provided adjacent to step surface638and a corresponding obliquely oriented surface652is provided adjacent step surface640.

Slider600further includes corner features660and662, which are positioned proximate corners670and672, respectively.FIG. 7illustrates a detailed view of feature662. Feature662includes top surfaces680and682and oblique surfaces684and686. A trench690is positioned between surfaces680and682and includes a top trench surface692and oblique trench surface694. The trench690defines an opening such that fluid flow can enter from trailing edge604. As trailing edge604of slider600is tilted towards a disc surface, air entering features660and662is pressurized, which creates a lifting force to prevent contact of slider600and the disc surface.

FIG. 8is a perspective view of a slider800according to an alternative embodiment of the present invention. The same reference numerals are used inFIG. 8as were used inFIG. 6for the same or similar elements. In this embodiment, slider800includes side rails802and804extending from lateral walls630and632, respectively, to trailing edge604. Side rails802and804define deeply recessed trenches806and808, respectively. Corner features802and804are formed at the trailing edge of side rails812and814, respectively and act to generate pressure at trailing edge604to prevent contact between slider800and a surface of a disc.

It is to be understood that even though numerous characteristics and advantages of various embodiments of the invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application for the data storage system while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. In addition, it will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other types of sliders having various configurations for flying above the surface of a storage medium without departing from the scope and spirit of the present invention. Also, the present invention can be used with any type of ramp load-unload or contact start-stop suspension, such as rotary and linear suspensions, and the transducing head can be of any type such as magnetic, magneto-resistive, optical or magneto-optical, for example.