The present invention relates generally to a data storage device, and more particularly but not by limitation to an air bearing for a head of a data storage device or system.
Data storage devices store digitally encoded information on discs. Heads read data from or write data to discs which are supported for rotation relative to a base chassis by a spindle motor or drive. Heads include transducer elements, such as magnetoresistive, magneto-optical or inductive elements for read or write operations. An actuator assembly moves the head relative to select data tracks on the disc to read or write data to the disc surface or media.
Typically the head includes a slider having an air bearing surface which is coupled to a head suspension assembly. Rotation of the disc creates an air flow along the air bearing surface to provide a pressure profile and lift force. The lift force of the air bearing is countered by a load force supplied via a load beam of the suspension assembly to define in part a fly height of the slider. Slider fabrication processes typically introduce shape variations across the air bearing profile. The pressure profile of the air bearing slider is sensitive to variation in the air bearing profile. For contact starts and stops (CSS) the raised surfaces of the air bearing contact the disc surface. During operation the air bearing slider can intermittently contact the disc surface. Contact stiction between the slider or air bearing surfaces and disc surface during CSS or intermittent contact can interfere with drive operations. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.
The present invention relates to a slider for a data storage device. The slider includes a bearing pad or surface having a raised bearing surface, a stepped bearing surface and a recessed pressure cavity or cavities. The recessed pressure cavity or cavities provides a reduced raised bearing surface area to reduce stiction and shape sensitivity. The recessed pressure cavity or cavities include a recessed cavity surface which is recessed from the raised bearing surface of the bearing surface or pad and a cavity step to the raised bearing surface. Other features and benefits that characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings.
Head 108 includes slider 126 which carries transducer elements for read or write operations. Rotation of the disc provides an air flow along air bearing surfaces of the slider 126 to provide a pressure profile or lifting force Fair bearing between the bearing surfaces and the disc surface or media. The lifting force Fair bearing of the air bearing slider 126 is countered by a load force to define in part a fly height Hfly of the slider or head above the disc surface. Slider fabrication processes typically introduce shape variations across the air bearing profile or cross or length dimension of the slider. In particular, slider fabrication processes typically introduce a cross curve and/or crown to the slider body or air bearing surfaces. The shape and contour of the crown and/or cross-curve is non-uniform and can vary within manufacturing tolerance parameters.
Shape variations in the fabricated air bearing slider, or across the air bearing profile, provide a shape sensitive pressure profile (e.g. twist or roll shape sensitivity) which affects fly height parameters of the air bearing slider. The present invention relates to an air bearing surface or pad having a recessed pressure cavity or cavities. The recessed pressure cavity or cavities provide a recessed surface area along a cross or length dimension of the bearing surface or pad to reduce contact stiction and/or shape sensitivity.
In the illustrated embodiment, cavity step 146 extends from the recessed cavity surface 142 to the raised cavity surface, although application is not limited to the specific embodiment or step rise shown. Also in the illustrated embodiment, the stepped bearing surface 136 extends between opposed sides 147, 148 of the bearing pad or surface 130 although application is not limited to the particular embodiment shown. Thus as described, the present invention provides a recessed pressure cavity for a bearing pad or surface to provide a recessed area for a bearing pad or surface (e.g. having a length to wide ratio less than or equal to 2.0) in addition to or in contrast to an elongate rail.
As previously described, rotation of the disc creates an air flow along the bearing pad or surface 130 to provide a pressure profile for operation. Air flow along the bearing pad or surface 130 is contained or pressurized relative to the pressure cavity 140 to provide an effective raised bearing surface or profile with reduced surface area and shape sensitivity. The raised bearing surface 134 of the pad or surface 130 is formed at the substrate level (zero etched depth) and the stepped bearing surface 136 and recessed cavity surface 142 are formed by a multiple stage milling process to form a plurality of etched depths for the stepped bearing surface 136 and the recessed cavity surface 142.
In the embodiment shown, raised bearing surfaces of the bearing pad or surface 130 are formed by a “U” shaped structure having a trailing edge portion 150 and opposed side portion 152, 154 elevated above the recessed cavity surface 142 to form the trailing edge cavity step 146 to the raised bearing surface and opposed side steps along opposed sides or side portion 152, 154 of the bearing pad or surface. Stepped surface 136 is formed proximate to a leading edge or portion of the “U” shaped structure to form a bearing step 156 from the recessed cavity surface 132 of the slider to stepped surface 136 and the leading edge cavity step 144 from the stepped surface to the recessed cavity surface 142.
In the embodiment shown, the “U” shaped structure forms the trailing edge cavity step extending the trailing edge and opposed side cavity steps to contain air for pressurization of the bearing. Thus, as shown, air flow is facilitated into the pressure cavity 140 via the recessed stepped bearing surface 136 and is contained by the raised bearing surface 134 having a higher elevation than the stepped bearing surface 136 to provide an effective raised bearing surface or profile for the bearing pad with reduced surface area and shape sensitivity. In an illustrative embodiment, the stepped bearing surface 136 is recessed approximately 0.1–0.3 μm from the raised bearing surface 134 and the recessed cavity surface is milled or etched to a cavity depth of approximately 2–3 μm. The “U” shaped structure is formed of thin walled structure which, in an illustrative embodiment, has a 20 μm thick or width.
In an alternate embodiment of a bearing pad or surface 130-4 illustrated in
For a magnetic recording head or slider 126-7 as shown in
Slider embodiments include leading edge pad(s) or surfaces 184 which define a raised bearing surface forward of the load point. In the illustrated embodiment, slider 126-7 includes raised bearing surfaces 186 along rails 188, 190 and along center pad 192 to provide raised bearing surface areas aft of the load point 176. Leading edge bearing pad 184 of known slider embodiments have a relatively large cross width dimension extending generally between opposed sides 200, 202 of the slider body to provide a relatively large bearing surface area forward of the load point 176 to provide pressurization and pitch. The relatively large bearing surface area increases shape sensitivity and stiction for the leading edge pad 184.
As graphically shown in
In the embodiment shown, the bearing pad 184-8 includes a trailing edge cavity step 148-8 and opposed side cavity steps from the recessed cavity surface 142-8 formed by relatively a thin walled “U” shaped structure having a raised surface height corresponding to the substrate surface of the slider body (i.e. 0.0 milled depth). The stepped bearing surface 136-8 and leading edge bearing step 156-8 and cavity step 144-8 are also formed by a relatively thin walled portion having a stepped surface height recessed below the substrate or raised air bearing surface 134-8.
The pads includes a cavity step to the raised bearing surface along the trailing edge and opposed sides of the pad as previously described. Thus as described, air flows into the recessed pressure cavity or cavities via the stepped bearing surface or surfaces and is pressurized to form an effective bearing surface having a relatively low stiction surface area. As shown in
As shown the slider 126-12 include a first recessed elevation or surface and a second deep recessed elevation or surface having an elevation recessed below the first recessed surface or elevation. In the embodiment shown, the slider include a first recessed surface portion 232 proximate to the leading edge of the pads 230-1, 230-2 to provide a bearing step 156-12 from elevation 232 to the stepped bearing surface 136-12. In the embodiment shown, the recessed cavity surfaces 142-12 include a second deep recessed elevation to provide a deep leading edge cavity step 144-12 from the stepped bearing surface 136-12 to the recessed cavity surface 142-12. In the illustrated embodiment, the bearing pads or surfaces 230-1, 230-2 also include a deep cavity step 146-12 along the trailing edge from the deep recessed cavity surface 142-12 to the raised bearing surface 134-12.
The slider 146-12 includes a deep cavity region 236 having the second deep recessed elevation along a leading edge region of the slider 126-12 proximate to bearing pads 230-1, 230-1. As shown, the slider 126-12 includes a deep recessed channel 240 along a raised rail portion 242 including a trailing edge step 244 to raised bearing surface 246 proximate to the trailing edge of the slider. The slider includes stepped rail or dam 250 having a stepped surface elevated above a first recessed portion or region 252 having a first recessed elevation and a leading edge cross rail or dam 254 having a raised surface elevation (0.0 milled depth). The deep recessed surfaces are milled or etched to a depth recessed below stepped surfaces and recessed surfaces as shown. For example, in one embodiment, the first recessed surface or surfaces are milled or etched to a depth of approximately 0.7–1.0 μm and the second deep recessed surface or surfaces are milled or etched to a depth of approximately 3.5 μm. In the illustrated embodiment, the slider 126-12 includes stepped dams 256 proximate to an outer edge of recessed surface portion 232 to contain air for pressurization.
In particular, in the slider embodiment 126-16 illustrated in
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 while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. In addition, although the preferred embodiment described herein is directed to a magnetic data storage device, it will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other data storage devices without department from the scope and spirit of the present invention.
Number | Name | Date | Kind |
---|---|---|---|
5055129 | Ghandehari | Oct 1991 | A |
5200868 | Chapin et al. | Apr 1993 | A |
5490026 | Dorius et al. | Feb 1996 | A |
5532890 | Dorius et al. | Jul 1996 | A |
5583722 | Dorius et al. | Dec 1996 | A |
5587858 | Dorius et al. | Dec 1996 | A |
5610784 | Dorius et al. | Mar 1997 | A |
5650892 | Dorius et al. | Jul 1997 | A |
5721650 | Crane et al. | Feb 1998 | A |
5726831 | White | Mar 1998 | A |
5777825 | Dorius | Jul 1998 | A |
5940249 | Hendriks | Aug 1999 | A |
6069769 | Dorius et al. | May 2000 | A |
6212032 | Park et al. | Apr 2001 | B1 |
6233118 | Boutaghou et al. | May 2001 | B1 |
6411468 | Park et al. | Jun 2002 | B1 |
6445543 | Gui et al. | Sep 2002 | B1 |
6459547 | Riddering et al. | Oct 2002 | B1 |
6477012 | Park et al. | Nov 2002 | B1 |
6504682 | Sannino et al. | Jan 2003 | B1 |
6560071 | Chapin et al. | May 2003 | B2 |
20020008939 | Boutaghou et al. | Jan 2002 | A1 |
20020071216 | Sannino et al. | Jun 2002 | A1 |
20030231429 | Boutaghou et al. | Dec 2003 | A1 |
20040120075 | Rajakumar | Jun 2004 | A1 |
20040201923 | Rao et al. | Oct 2004 | A1 |
Number | Date | Country | |
---|---|---|---|
20050083609 A1 | Apr 2005 | US |