Abstract:
Systems and apparatus are described for modifying fluid flow in a hard disk drive system to reduce cross-track motion. The systems and methods provide advantages because they include at least one flow modification element. In some embodiments, the flow modification system comprises a set of approximately parallel combs occupying a portion of the space present in between the disks in the hard disk drive system. The combs change the flow pattern of the fluid and act as a momentum channeling mechanism relative to the actuator assembly and suspension assemblies resulting in a considerable reduction in track misregistration error. Various embodiments of the invention include baffle-integrated combs, fixture-integrated combs, contoured enclosure surfaces, and enclosure attached combs.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to the field of hard disk drives. More particularly, the invention relates to hard disk drives having at least one flow modification element disposed adjacent to at least one data storage disk. 
     2. Discussion of the Related Art 
     Conventional hard disk drive  100 , a portion of which is shown in  FIG. 1 , includes at least one rotating disk  110  on which data is stored in concentric tracks. Disk drive  100  includes read-write head  120  disposed on aerodynamically operable slider assembly  130  and back plate  140 . Slider assembly  130  is disposed at the end of the actuator arm portion of actuator assembly  160 . Disk  110  couples with spindle  170  to rotate in a counterclockwise direction (shown as “A” in FIG.  1 ), thereby causing airflow in direction A. The airflow impinges upon portions of actuator assembly  160  and slider assembly  130 . Movement of actuator assembly  160  is accomplished using a conventional voice coil motor (not shown in FIG.  1 ). 
     Head  120  reads data from and writes data to approximately concentric data tracks  210 , shown schematically in FIG.  2 . While disk drive  100  is in operation, actuator assembly  160  experiences cross-track motion  220  as head  120  attempts to follow track  210 . 
     Cross track motion  220  of head  120  can be measured as track misregistration (TMR). Larger levels of TMR limit the amount of data that can be written to and retrieved from disk drive  100 . Cross track motion  220  results from several disturbances that couple into head  120 . Some of the major disturbances include disk vibration, spindle bearing runout (repeatable and non-repeatable), slider assembly  130  vibration, actuator arm vibration, and drive enclosure vibration. 
     In order to accurately read and write data, a servo control system is employed to keep head  120  aligned with track  210 . The servo control system has its own attenuation and amplification characteristics, and is typically ineffective above about 4 kHz. Head  120  vibration spectrums for conventional disk drives  100  exhibit substantial vibrational movement of head  120  in a high frequency region of around 5 to 25 kHz. The servo control system is ineffective in compensating for the vibration in the high frequency region. 
     A common approach to increase the storage capacity of a disk drive  100  is to increase the track  210  density (tracks per inch, or TPI). Due to the continuing push for greater track  210  densities, allowable cross track motion  220  is decreasing in absolute terms. However, drives are spinning at higher speeds. Higher speeds increase the amount of cross track motion  220  of head  120 . The increase in TMR (i.e., cross track motion  220 ) in the high frequency region is more pronounced at higher disk rotation speeds. A drive is typically designed so that the total TMR cannot exceed a certain limit (e.g., approximately ten percent of the track  210  width). As a result of this limit, at higher rotational speeds, no remaining TMR budget is available at the higher rotational frequencies, and the vibrational energy within the TMR spectral bandwidth of 0-25 kHz frequency range needs to be minimized in order to provide error-free operation of disk drives  100 . 
     Disk drives  100  are known to those skilled in the art. For example, a conventional disk drive  100 , such as the disk drive described by U.S. Pat. No. 5,526,203, can include baffle  190  disposed adjacent to upstream from actuator assembly  160 . Baffle  190  is placed adjacent to the outermost diameter of disks  110 . According to the U.S. Pat. No. 5,526,203 patent, one motivation for using baffles  190  is to block contaminants generated by actuator assembly  160  from being deposited on disks  110 . Baffles  190  have the unintended effect of blocking airflow that would otherwise impinge on portions of actuator assembly  160  disposed outside outer edges  240  of disks  110 . Such airflow blocking can reduce TMR in some designs. 
     However, baffles  190  cannot effectively reduce the airflow contributions (or momentum transfer) that cause cross track motion  220 . Baffles  190  do not modify the airflow interaction with portions of actuator assembly  160  disposed between disks  110 . Therefore, what is required is a solution that reduces the momentum transfer caused by airflow impinging these portions of actuator assembly  160  adjacent to disk  110  data surfaces. The reduction of momentum transfer decreases cross track motion  220  of head  120 . Heretofore, the requirement of reduced cross track motion  220  referred to above has not been fully met. 
     SUMMARY OF THE INVENTION 
     One goal of the invention is to reduce cross track motion  220  in a disk drive. Another goal of the invention is to provide a comb, or other device to reduce cross track motion  220  in a disk drive. 
     A first aspect of the invention is implemented in embodiments that are based on a baffle integrated comb disk drive. The disk drive includes a spindle, data storage disks, slider assemblies, an actuator assembly, a baffle, and combs. The spindle is adapted to rotate about a longitudinal axis. The disks are surrounded by fluid medium. The disks are mounted on the spindle to rotate therewith about the spindle longitudinal axis. Rotation of the disks in a first direction (indicated by “A” in  FIG. 1 ) creates a flow of the fluid medium in the first direction. At least one of the disks has approximately concentric tracks disposed at different radial positions between the disk&#39;s outer edge and the disk&#39;s inner edge. Each slider assembly includes at least one transducer head capable of reading and writing information on one of the disks. The actuator assembly positions the slider assemblies over the tracks. 
     The baffle is disposed upstream of the actuator assembly. The baffle extends in the direction of the spindle longitudinal axis and has an inner surface disposed at least one millimeter outside of the outer edges of the disks. 
     The combs are mounted on the baffle. At least one of the combs is disposed adjacent to at least one of the disks to form a gap between the comb and a corresponding adjacent disk. The gap is disposed in the direction of the spindle longitudinal axis and is in a range from approximately 0.1-millimeter to approximately 20 millimeters. At least one of the combs extends radially inward from a comb outer edge to a comb inner edge. A portion of the comb outer edge is disposed at the inner surface of the baffle. At least one of the combs is disposed upstream of a corresponding actuator assembly. At least one of the combs extends in a disk circumferential direction from a leading edge to a trailing edge. The leading edge is disposed upstream of the trailing edge. At least one of the combs extends radially inward from the baffle plate more than approximately two percent of a distance between an inner edge and the outer edge of the corresponding adjacent disk. 
     A second aspect of the invention is implemented in embodiments that are based on a fixture integrated comb disk drive. These embodiments include a comb fixture coupled with combs. The comb fixture is disposed apart from the actuator assembly, and has an inner surface separated by a first distance from the outer edges of the disks. The first distance is greater than approximately one millimeter. 
     The combs extend inwardly from the comb fixture. At least one of the combs is disposed adjacent to a corresponding adjacent disk to provide a gap between the comb and the corresponding adjacent disk. The gap is disposed in the direction of the spindle longitudinal axis and is in a range from approximately 0.1 millimeters to approximately 20 millimeters. At least one comb extends circumferentially around the spindle longitudinal axis. 
     A third aspect of the invention is a disk drive with at least one contoured enclosure element. Embodiments according to this aspect can have one or more of the following enclosure elements. The first type of enclosure element according to this aspect comprises a first large portion and a depressed contoured portion with a depressed region. The second type of enclosure element according to this aspect of the invention includes a second large portion and a protruded contoured portion with a protruded region. 
     The first large portion has a surface proximal to an adjacent disk outer surface and is disposed longitudinally outside the actuator assembly to form a gap in approximately the longitudinal direction between the first large portion proximal surface and the adjacent disk outer surface of at least approximately 0.1 millimeter. The depressed contoured portion is disposed circumferentially adjacent to and upstream of the actuator assembly. The depressed region is disposed closer to the adjacent disk outer surface than the first large portion. The first large portion covers more than approximately three times the amount of the adjacent disk outer surface than the amount of the outer surface that is covered by the depressed region. 
     The second large portion has a surface proximal to the adjacent disk outer surface and forms a gap in approximately the longitudinal direction between the second large portion proximal surface and the adjacent disk outer surface of no more than approximately 20 millimeters. The protruded region is disposed longitudinally outside the actuator assembly. The protruded region has a width outside the outer edge of the adjacent disk greater than a width of a portion of the actuator assembly adjacent and longitudinally interior of the protruded region. The protruded region is disposed farther from the adjacent disk outer surface than the second large portion. The second large portion covers more than approximately three times the amount of the adjacent disk outer surface than the amount of the outer surface that is covered by the protruded region. 
     These, and other, goals and aspects of the invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A clear conception of the advantages and features constituting the invention, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments. The embodiments are illustrated in the drawings, wherein like reference characters (if they occur in more than one view) designate the same parts. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale. 
         FIG. 1  is a top view of a portion of a conventional disk drive. 
         FIG. 2  is a schematic view of the top of a data storage disk and actuator arm. 
         FIG. 3A  is a perspective view of the front of portions of a disk drive having combs integrated into a baffle, representing a first embodiment of the invention. 
         FIG. 3B  is a top view of a portion of a baffle integrated comb disk drive, representing the first embodiment of the invention. 
         FIG. 4  is a perspective view of an integrated baffle/comb assembly having a baffle plate. 
         FIG. 5  is a perspective view illustrating how the baffle-integrated combs assemble into the space between the data storage disks. 
         FIGS. 6A-6C  provide different cross-sectional views of circumferentially tapered comb designs used in the present invention. 
         FIG. 7A  is a perspective view of a portion of disk drive having fixture-integrated combs, representing a second embodiment of the invention. 
         FIG. 7B  is a perspective view of fixture integrated combs coupled with disk drive back plate having a fixture integrated therein. 
         FIG. 7C  is a perspective view of the fixture-integrated combs including some additional portions of the disk drive. 
         FIGS. 8A and 8B  are perspective views of contoured cover plates, used in the present invention. 
         FIG. 9A  is a perspective view of combs attached directly to a disk drive cover plate. 
         FIG. 9B  is a perspective view of combs attached directly to a disk drive base plate. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description of preferred embodiments. Descriptions of well-known components and processing techniques are omitted so as not to unnecessarily obscure the invention in detail. 
     The invention reduces cross-track motion  220  of read-write head  120  over the complete spectral bandwidth of interest for a disk drive by introducing components that alter fluid movement in the disk drive. The reduction of cross-track motion  220  is accomplished by reducing the total cross-track momentum of fluid molecules that interact with disk drive components. The fluid can be air or another fluid, such as helium. Considerable decreases in design effort for dynamic disk drive components can be realized by implementing the invention with passive components. These passive components can be introduced at low cost and allow greater disk drive design flexibility. 
     A portion of a baffle-integrated comb (BIC) disk drive  300  according to the principles of the invention is depicted in  FIG. 3A and 3B . Placing flow modifier combs, such as baffle integrated combs  310 , in the space between disks  110  of BIC disk drive  300  reduces the fluid molecule momentum transfer to key portions of BIC disk drive  300 . Baffle-integrated comb disk drives  300  typically have more than one disk  110 . However, in some embodiments, two combs can be used according to the invention for a disk drive that has only one data disk. 
     Combs  310  provide a considerable reduction in cross-track motion  220  in all disturbance frequency regions, but particularly for the high frequency region (where the servo control system is not effective). Combs  310 , and other flow modification elements according to the invention, are placed very close to corresponding adjacent rotating disks  110  to modify the flow characteristics of the fluid medium moved by disks  110 . 
     The primary energy source for the fluid flow and other vibration disturbances of read-write head  120  is rotating spindle  170 . The energy from spindle  170  is mainly partitioned off into the mechanical components of the corresponding disk drive (such as BIC disk drive  300 ), the fluid medium inside the drive enclosure, and as heat. Fluid medium receiving energy from spindle  170  serves as a secondary source of excitation for components inside BIC disk drive  300 , so that the fluid medium flow affects the amount of cross-track motion  220 . Cross-track motion  220  motion is a direct result of the momentum transfer that takes place as the high-energy fluid molecules impinge actuator assembly  160 . 
     Designing or locating the combs so that an energy dissipating flow region is developed also reduces this transfer of momentum. Because the comb acts as an obstruction to the normal flow of the rotating fluid, the fluid flow becomes very complex after interacting with the comb. The contact of the fluid with the comb results in flow separation, creation of vortices and mixing. These effects change the momentum vectors of the fluid molecules to a direction other than the nominal flow direction (shown as “A” in FIG.  1 ). This change in the fluid molecule momentum vectors translates into smaller momentum vectors of the fluid molecules in the cross-track motion  220  direction in the region of operation for actuator assembly  160 . Further beneficial effects can be obtained through selection of materials and component geometry. Examination of  FIG. 3B  in conjunction with FIG.  1  and  FIG. 2 , reveals that fluid flow impingement on suspension arm  150 , slider assembly  130  and read-write head  120  causes movement of these components in a direction that is not parallel to the track  210  direction. This non-parallel movement occurs because suspension arm  150  extends lengthwise in a direction other than the radial direction of disk  110 . The angle between the radial direction and the suspension arm  150  lengthwise direction increases for tracks  210  disposed on the outer diameter of disk  110 . 
     Introducing the comb increases power consumption due to cross-sectional and surface drag of the fluid medium. The higher power budget for the BIC drive  300  can be accommodated by careful selection of a comb unit design, or by considering other power saving mechanisms and designs, such as a lower number of disks  110 , thinner disks  110  etc. These power reduction options are more readily available because of reduced cross-track motion  220  provided by the combs. Using fewer disks  110  also decreases the cost for read-write heads  120  in a disk drive. 
     Baffle Integrated Combs 
     One aspect of the invention provides a baffle integrated comb assembly for reducing cross track motion in a baffle integrated comb disk (BIC) drive. Portions of BIC drive  300  are shown in FIG.  3 A and FIG.  3 B. Some embodiments of baffle/comb assemblies  400  according to this aspect are illustrated in FIG.  4  and FIG.  5 . BIC drive  300  comprises spindle  170 , data storage disks  110 , slider assemblies  130 , actuator assembly  160 , baffle integrated combs  310  and baffles  320 . 
     Spindle  170  is conventionally coupled with a spindle motor to rotate about spindle longitudinal axis (shown as “C” in  FIG. 3A ) when BIC disk drive  300  is powered on. Each disk  110  is mounted on spindle  170  to rotate therewith about the spindle longitudinal axis in a first direction (e.g., either clockwise or counterclockwise around spindle longitudinal axis). Each disk  110  has an inner edge  230  and an outer edge  240 . At least one of disks  110  has concentric tracks  210  disposed at different radial positions between inner edge  230  and outer edge  240 . Rotating disks  110  create a flow of fluid medium contained in BIC drive  300  in the first direction. 
     BIC drive  300  shown in  FIG. 3B  includes conventional slider assemblies  130 . Each slider assembly  130  includes at least one transducer head capable of reading and writing information on one of disks  110 . BIC drive  300  also includes actuator assembly  160  for positioning slider assemblies  130  over concentric tracks  210 . 
     BIC drive  300  includes a baffle/comb assembly  400  having integrated baffle  320  disposed upstream of actuator assembly  160 . Baffle  320  extends in the direction of the spindle  170  longitudinal axis and has an inner surface disposed at least one millimeter outside of the outer edges  240  of disks  110 . 
     As shown in FIG.  4 A and  FIG. 5 , baffle integrated combs  310  are mounted on baffle  320 . Each comb  310  is disposed adjacent to at least one disk  110  to form a comb-to-disk spacing  510  between comb  310  and a corresponding adjacent disk  110 . Comb to disk spacing  510  is oriented approximately in the direction of the spindle  170  longitudinal axis and is in a range from approximately 0.1-millimeter to approximately 20 millimeters. In some embodiments, comb to disk spacing  510  is less than approximately 0.4 millimeters. 
     At least one comb  310  extends radially inward from a comb outer edge (otherwise referred to as a comb “base”  325 ) to a comb inner edge. B-comb base  325  is disposed approximately at the inner surface of baffle  320 . The comb inner edge for triangular shaped combs comprises comb tip  330 . 
     Each comb  310  is disposed upstream of a corresponding actuator assembly  160 , and, as shown in  FIG. 5 , extends in a disk  110  circumferential direction from a leading edge  340  to a trailing edge  350 . Leading edge  340  is disposed upstream of trailing edge  350 . 
     As shown in  FIG. 3B , each comb  310  extends radially inward from baffle  320  more than approximately two percent of a radial separation distance between disk inner edge  230  and disk outer edge  240  of a first adjacent disk  110 . 
     Typically, comb&#39;s  310  maximum radially inward extent is approximately thirty to eighty percent (30-80%) of the disk inner edge  230  to disk outer edge  240  radial separation distance. As shown in  FIG. 3B , comb  310  trailing edge is typically approximately parallel to the leading edge of actuator assembly  160  when actuator assembly  160  is positioned to read data track  210  near disk inner edge  230 . 
     Combs  310  can be manufactured by molding the whole of baffle/comb assembly  400  at once. Baffle/comb assembly  400  can be machined as a single piece. For these single piece baffle/comb assembly  400  approaches baffle  320  comprises a baffle plate. Alternatively, combs  310  can produced as individual pieces and stacked one on top of the other. Each individual piece includes a baffle element  410  extending radially outward from comb base  325 . Each baffle element  410  typically has a greater thickness than its corresponding comb  310  to provide space between adjacent B-combs for corresponding disks  110 . The baffle/comb assembly  400  using individual comb  310  pieces does not need a baffle plate. 
     In some embodiments, BIC disk drive  300  includes a second set of combs extending radially inward from an outer attachment element inner surface. The second set of combs can be baffle integrated combs  310 , or fixture integrated combs (as described below with reference to FIG.  7 A). The outer attachment element inner surface has a diameter greater than the outer edge of disks  110 , each of the second set of combs is disposed in a position adjacent to at least one disk  110 , and is disposed downstream of slider assemblies  130 . The slider assemblies  130  are disposed on the distal end of actuator assembly  160 . 
     In some embodiments, at least one of comb  310  comprises more than one element. At least two of the comb elements are separated from each other by an intra-comb gap. The intra-comb gap extends radially from approximately the comb  310  inner diameter to approximately the comb outer diameter. 
     In some embodiments, at least one comb  310  has a textured surface adapted to modify a fluid flow impinging on an adjacent slider assembly  130 . For example, very-small v-shaped grooves disposed on either the distal or the proximal comb  310  surface (or on both surfaces) and oriented in a direction approximately perpendicular to the fluid flow results in decreased drag losses and concomitant power consumption reduction. 
     As shown in  FIGS. 6A-6C  comb  310  can be tapered so that the comb thickness increases form leading edge  440  to trailing edge  450 . Comb  310  can have an approximately constantly sloped taper as shown in  FIG. 6B , or alternatively can have a variably sloped taper as shown for example in  FIG. 6C  where the slope generally increases as the thickness of the B-comb increases. 
     As shown in  FIG. 6A , at least one comb  310  can also have a thickness that increases from the comb inner diameter to the comb outer diameter. 
     Fixture Integrated Combs 
     A portion of a fixture integrated comb (FIC) disk drive  700  is shown in  FIGS. 7A-7C . The FIC disk drive  700  has a comb fixture  710  integrated with a back plate or other portion of a disk drive. FIC disk drive  700  includes the conventional elements described above for BIC disk drive  300 . As shown in  FIG. 7A , comb fixture  710  is disposed apart from actuator assembly  160 , and has an inner surface separated in an approximately radial direction from the disk outer edge  240  by a fixture to disk spacing  725 . Fixture to disk spacing  725  is greater than approximately one millimeter. 
     Fixture integrated combs  720  are coupled with and extend inwardly from comb fixture  710 . Similar to baffle integrated combs  310 , each fixture integrated comb  720  is disposed adjacent to a corresponding adjacent disk  110  to form a comb to disk spacing  510  between the comb and the adjacent disk. Comb to disk spacing  510  is disposed in the direction of the spindle longitudinal axis (shown as “C” in  FIG. 7A ) and is in a range from approximately 0.1 millimeters to approximately 20 millimeters. In some embodiments, comb to disk spacing  510  is less than approximately 0.4 millimeters. 
     Comb  720  extends inwardly at least two percent of a distance from comb fixture  710  to disk inner edge  230  of the corresponding adjacent disk. Comb  720  extends circumferentially around the spindle  170  longitudinal axis. Typically, comb  720  extends circumferentially through an angular distance of at least twenty degrees. 
     Various embodiments of FIC disk drive  700  have been developed. For some embodiments comb  720  includes a first portion and a second portion. The first portion has an outer diameter approximately equal to the comb fixture  710  inner surface. The second portion extends closer to the slider assemblies  130  and has an outer diameter less than the comb fixture  710  inner surface. Other combs  720 , do not include such distinct portions. 
     In some embodiments, FIC disk drive  700  includes baffle  190  disposed outside disk  110  outer edges  240 . Baffle  190  also has an edge spaced closely to a segment of disk outer edges  240 . For these FIC disk drives  700  a first portion of the at least one comb  720  extends radially inward beyond the outer edge  240  of the corresponding adjacent disk  110 . An edge of the first portion of comb  720  proximal to disk outer edge  240  extends circumferentially towards actuator assembly  160  forming a gap between the proximal edge of comb  720  and baffle  190  of no less than ten millimeters. 
     Contoured Enclosure Surfaces 
     Another aspect of the invention provides a disk drive with at least one enclosure element with a contoured surface. The contoured enclosure surface reduces cross-track motion  220 . The contoured surface can be a portion of a cover plate or a portion of a base plate that provides the desired fluid flow modification in the disk drive. Portions of two embodiments of this aspect of the invention are shown in FIG.  8 A and FIG.  8 B. 
     Other than the contoured enclosure surface, disk drives according to this aspect typically have the conventional elements described above for BIC drive  300 . As shown in FIG.  8 A and  FIG. 8B , disk  110  has outer edge  240 , outer surface  805 , inner edge  230 , and an inner surface (not shown). The inner surface and outer surface  805  are approximately perpendicular to the spindle longitudinal axis (shown as “C” in FIG.  3 ). 
     The enclosure element can include a large somewhat flat portion combined with a depressed contoured portion, such as a cover plate with a depressed contour (depressed contour cover plate  810 ) as shown in FIG.  8 A. Depressed contour cover plate  810  includes large cover plate portion  815 D and a depressed contoured portion having a depressed region  820 . The proximal surface of depressed region  820  provides flow modification for outer surface  805  of the uppermost disk in a disk drive similar to the flow modification provided by baffle integrated comb  310  or fixture integrated comb  720 . Large portion  815 D has a surface (e.g., the bottom side of depressed contour cover plate  810 ) proximal to an adjacent disk outer surface  805 . The proximal surface of large portion  815 D is disposed longitudinally outside (e.g. above) actuator assembly  160  to form a gap in approximately the longitudinal direction between the proximal surface of large portion  815 D and outer surface  805  of at least approximately 0.1 millimeter. The depressed contoured portion is disposed circumferentially adjacent to and upstream of actuator assembly  160 . Depressed region  820  is disposed closer to outer surface  805  than large portion  815 D. In some embodiments the distance between depressed region  820  and outer surface  805  is less than approximately 0.8 millimeters. Large portion  815 D typically covers more than approximately three times the amount of outer surface  805  covered by depressed region  820 . 
     For other embodiments according to this aspect the enclosure element can be a large somewhat flat portion combined with a protruded contoured portion such as a cover plate with a protruded contour (protruded contour cover plate  850 ) as shown in FIG.  8 B. Protruded contour cover plate  850  includes large P-cover plate portion  815 P and protruded contour portion having a protruded region  860 . Large portion  815 P has a surface proximal to outer surface  805  and forms a gap in approximately the longitudinal direction between the proximal surface and outer surface  805  of no more than approximately 20 millimeters. Protruded region  860  is disposed above actuator assembly  160 . Protruded region  860  has a width above the of the adjacent disk outer edge  240  greater than a width of a portion of actuator assembly  160  adjacent and longitudinally interior of the protruded region  860 . Protruded region  860  is disposed farther from outer surface  805  than large portion  815 P. Large portion  815 P typically covers more than approximately three times the amount of outer surface  805  covered by protruded region  860 . The proximal surface of large portion  815 P disposed upstream of actuator assembly  160  provides flow modification for outer surface  805  of the uppermost disk in a disk drive similar to the flow modification provided by baffle integrated comb  310  or fixture integrated comb  720 . For some embodiments, the distance between the proximal surface of large portion  815 P and outer surface  805  is less than approximately 0.8 millimeters. 
     Some other embodiments of the invention according to this aspect include base plates having elements with depressed regions or protruded regions as described above for the cover plates. The depressed region of base plate elements analogous to depressed contour cover plate  810 , and the large P-cover portions of base plates elements analogous to protruded contour cover plate  850  provide flow modification for outer surface  805  of the lowermost disk in a disk drive. Finally, still other embodiments have both a contoured cover plate and a contoured base plate element as described above. These contoured enclosure elements can be used with baffle integrated combs  310  or fixture integrated combs  720  as described above. 
     Enclosure Attached Combs 
     Another aspect of the invention provides a enclosure attached comb disk drive assembly comprising a spindle  170 , at least one data storage disk  110 , conventional slider assemblies  130 , an actuator assembly  160 , an enclosure attached comb  910 , an enclosure element, and attachment elements  930 . Disk  110  has an outer radial edge, an outer surface, an inner radial edge, and an inner surface. Each slider assembly  130  includes at least one transducer head capable of reading and writing information on an adjacent disk  110 . The enclosure element can be either a cover plate  910 , or an element of a base plate including an attachment surface  940 . The enclosure element has an interior surface proximal to attachment elements  930 .