Abstract:
A limit stop filter support apparatus for use in controlling fluidic currents and limiting movement of an actuator within a housing, such as in a data storage device. First and second filter retention members extend from a filter support base to confine opposing ends of a filter used to filter fluidic currents within the housing, and a cantilevered limit stop extends from the base to contactingly limit movement of an actuator moveable within the housing. The limit stop preferably comprises a spring member supporting a latch member, the latch member selectively confining the actuator in a parked position. The first and second retention members each preferably include a shroud surface adjacent an outer peripheral edge of a rotatable storage medium to direct the fluidic currents established by rotation of the medium.

Description:
FIELD OF THE INVENTION  
       [0001]     The claimed invention relates generally to data storage devices and more particularly, but without limitation, to an apparatus which controls recirculating fluidic currents established during active operation of a data storage device and selectively limits travel of an actuator of the device during periods of inactivity.  
       BACKGROUND  
       [0002]     Disc drives are digital data storage devices which store and retrieve large amounts of user data in a fast and efficient manner. The data are recorded on the surfaces of one or more rigid data storage discs affixed to a spindle motor for rotation at a constant high speed.  
         [0003]     One or more data transducing heads are controllably positioned by an actuator to read data from and write data to tracks defined on the recording surfaces. The heads are configured to be hydrodynamically supported over the recording surfaces by fluidic currents established by the high speed rotation of the discs.  
         [0004]     It is desirable to control the flow of the fluidic currents within a disc drive housing and to filter particulates from the currents. Particles can increase the chances to induce undesired and potentially catastrophic contact between the heads and the discs of the data storage device. Additionally, controlling the flow of the fluidic currents promotes a desirable reduction of turbulence in the vicinity of the heads. Turbulence can induce undesired vibrations in the heads, thereby adversely affecting data reading and writing performance.  
         [0005]     In providing effective filtering and air flow control, disc drive designers are constrained by a number of factors, including continually reduced form factors and internal clearance issues. Thus, with the continued demand for higher performance data storage devices, there remains a continual need for improved approaches to controlling and filtering recirculating fluidic currents within such devices. It is to such improvements that the claimed invention is directed.  
       SUMMARY OF THE INVENTION  
       [0006]     In accordance with preferred embodiments, a limit stop filter support apparatus includes first and second filter retention members respectively extending from a filter support base to confine opposing ends of a filter used to filter fluidic currents within a housing. A cantilevered limit stop extends from the filter support base to contactingly limit movement of an actuator moveable within the housing.  
         [0007]     The limit stop preferably comprises a spring member supporting a latch member, the latch member selectively confining the actuator in a parked position. The first and second retention members each preferably include a shroud surface adjacent an outer peripheral edge of a rotatable storage medium to direct the fluidic currents established by rotation of the medium.  
         [0008]     In accordance with further preferred embodiments, a data storage device is provided which includes a rotatable storage medium which establishes recirculating fluidic currents during rotation, an actuator which controllably moves a data transducing head adjacent a surface of the medium, and a limit stop filter support.  
         [0009]     The limit stop filter support includes a base from which extend first and second filter retention members and a cantilevered limit stop, the first and second retention members confining opposing ends of a filter used to filter said fluidic currents, the limit stop contactingly limiting movement of the actuator.  
         [0010]     These and various other features and advantages which characterize the claimed invention will become apparent upon reading the following detailed description and upon reviewing the associated drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a partial cut-away plan view of a data storage device incorporating a limit stop filter support apparatus constructed in accordance with preferred embodiments of the present invention.  
         [0012]      FIG. 2  shows a top perspective view of the limit stop filter support apparatus of  FIG. 1 .  
         [0013]      FIG. 3  shows the limit stop filter support apparatus in greater detail.  
         [0014]      FIG. 4  illustrates a flow chart for a preferred method of assembling the disc drive of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0015]      FIG. 1  provides a top plan view of a data storage device (DSD)  100  constructed in accordance with preferred embodiments of the present invention. A base deck  102  and a top cover  104  (shown in partial cut-away) cooperate to form an environmentally controlled housing for the DSD  100 .  
         [0016]     A spindle motor  106  rotates a number of magnetic recording discs  108  at a constant, high speed. A rotary actuator  110  controllably moves a corresponding number of data transducing heads  112  across recording surfaces of the discs  108  through application of current to a voice coil motor assembly (VCM)  114 .  
         [0017]     The heads  112  are aerodynamically supported over the recording surfaces by fluidic recirculating currents established by rotation of the discs  108 . For purposes of the present discussion, it will be contemplated that the DSD  100  includes two discs  108  and four heads  112 , although other numbers of discs and heads can be used as desired.  
         [0018]     A flex circuit assembly  116  provides electrical communication paths between the actuator  110  and a disc drive printed circuit board (PCB) mounted to the underside of the base deck  102 . Preferably, when the DSD  100  is deactivated, the PCB commands the actuator  110  to position and bring the heads  112  to rest on texturized landing zones  118  near the innermost diameters of the discs  108 . By positioning the heads  108  on the texturized landing zones  118 , the actuator  110  is contactingly engaged with a limit stop filter support apparatus  120 , which preferably confines the actuator  110  in a parked position as described below.  
         [0019]     Vectors of airflow  122  indicate the direction of flow of fluidic currents developed by rotation of the discs  108  in a direction shown by rotational direction vector  124 . As the fluidic current progresses around the disc, a shroud portion  126  of the apparatus  120  directs a portion of the flow through a secondary filter  128 , while another portion of the flow is directed through a primary filter  130 , confined within a shroud channel  132 . The secondary filter  128  is preferably supported and confined by a filter feature portion  134  of the apparatus  120 .  
         [0020]     In addition to diverting a portion of the flow, the shroud portion  126  reduces wind resistance encountered by the disc  108  during rotation. The flow diverted by the shroud portion  126  through the secondary filter  128  continues to progress through a bypass channel  136 , and into contact with a desiccant chamber  138 , which extracts humidity from the flow. The apparatus  120  is preferably mounted to the base deck  102  during disc drive manufacturing after a head-disc merge operation wherein the heads  112  are loaded onto the discs  108 .  
         [0021]     As will be recognized, a head-disc merge operation generally entails affixing the actuator  110  to the base deck  102  with the heads  112  beyond the outermost diameters of the discs  108 , and then rotating the actuator  110  to advance the heads  112  to the landing zones  118 . The apparatus  120  is mounted to the base deck as a top down assembly process step. Once the spindle motor  106  supporting the discs  108  and actuator  110  supporting the heads  112  have been affixed to the base deck  102 , the apparatus  120  is secured to the base deck  102 .  
         [0022]     As shown by  FIG. 2 , the filter feature portion  134  of the apparatus  120  includes an outer filter retention member  140  and an inner filter retention member  142  (also referred to herein as first and second filter retention members). The members  140 ,  142  are respectively supported by a filter support base  144  and are configured to support opposing ends of the filter  128 . The aforementioned shroud portion  126  is supported by the inner filter retention member  142 , as shown. The outer filter retention member  140  can further be provided with a similar shroud portion, as desired, depending on the requirements of a given application.  
         [0023]     Adjacent the outer filter retention member  140  and cooperating with the filter support base  144  is an outer stop portion  146 . The outer stop portion  146  includes a spring member  148  with a proximal end communicating with the filter support base  144 . The outer stop portion further has an actuator latch member  150  supported on a distal end of the spring member  148 .  
         [0024]     The actuator latch member  150  captures a corresponding latch feature of the actuator  110  when the DSD  100  positions the heads  112  adjacent the landing zones  118 . This serves to place the actuator  110  in a parked position while data transfer operations are suspended during a period of inactivity. Preferably, the apparatus  120  is formed using a suitable injection molding operation from a durable polymer such as a polycarbonate resin, but may be formed from other moldable, rigid polymers, or materials such as engineered ceramics.  
         [0025]      FIG. 2  also shows the outer filter retention member  140  provides an outer filter retention channel  152 , and the inner filter retention member  142  provides an inner filter retention channel  154 , wherein fluidic currents developed by rotation of the disc  108  (of  FIG. 1 ) of the DSD  100  are substantially sealed from migration around the secondary filter  128  (of  FIG. 1 ) and passed through the secondary filter  128 .  
         [0026]      FIG. 3  shows a disc stack assembly  156  formed from a number of discs  108  stacked on the spindle motor  106  and clamped thereto by a disc clamp  158 . The disc stack assembly  156  and the actuator  110  in combination collectively form mechanically active components (MAC)  160  of the DSD  100 . During data exchange operations of the DSD  100 , the MAC  160  generates sub-micron particles and dislodges sub-micron particles from other components internal to the DSD  100 .  
         [0027]     Empirical data shows that operating the DSD  100  with the primary filter  130  alone, a cleanup time of about 42 seconds is consistently achieved. However, with the addition of the OSFF  120  to the DSD  100 , the cleanup time dropped and a cleanup time of about 13 seconds is consistently achieved. To measure cleanup time, at spin-up of the DSD  100 , a continuous sample of the fluidic currents generated by the spinning disc  108  is provided to a particle counter (not shown). The particle counter records a presence and number of particles of substantially 0.3 microns (and greater) present in the sampled fluidic currents.  
         [0028]     At spin-up of the disc stack assembly  156 , the particle counter registers a start time and measures an elapse time from spin-up to achieve an absence of particles in the sampled fluidic currents. By cycling the fluidic currents through the primary and secondary filters,  130  and  128  respectively (of  FIG. 1 ), particles are extracted from the fluidic currents. Additionally, over the life of the DSD  100 , the primary and secondary filters,  130  and  128  respectively, continue to extract particles from the fluidic currents generated during operation of the DSD  100 . An ability of the DSD  100  to continually self-clean during operation of the MAC  160  reduces a probability of particle induced catastrophic failure of the DSD  100 . By reducing the cleanup time; the probability of particle induced catastrophic failure of the DSD  100  is further reduced.  
         [0029]      FIG. 4  shows a flow chart  200  of steps included within a preferred method of forming the DSD  100 . The method commences at start process step  202 , and continues at process step  204  where the transducing heads  112  are aligned adjacent the corresponding discs  108  to form the mechanically active component combination  160 . At process step  206 , the MAC  160  is secured to the base deck  102 . At process step  208 , the limit stop filter support apparatus  120  is positioned adjacent the MAC  160  and at process step  210 , the apparatus  120  is secured to a base surface of the base deck  102 . At process step  212 , the filter  128  is positioned within and confined by the filter feature portion  134 , after which the process ends at step  214 .  
         [0030]     In view of the foregoing, it will now be appreciated that the present invention, as embodied herein and as claimed below, is generally directed to a limit stop filter support apparatus (such as  120 ).  
         [0031]     In accordance with preferred embodiments, the apparatus includes first and second filter retention members (such as  140 ,  142 ) respectively extending from a filter support base (such as  144 ) to confine opposing ends of a filter (such as  128 ) used to filter fluidic currents within a housing (such as  102 ,  104 ). A cantilevered limit stop (such as  146 ) extends from the filter support base to contactingly limit movement of an actuator moveable within the housing.  
         [0032]     It is to be understood that even though numerous characteristics and advantages of embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of embodiments of the invention, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms wherein the appended claims are expressed. For example, the particular elements may vary depending on the particular application of the combination outer stop with shrouding and filter features without departing from the spirit and scope of the present invention.  
         [0033]     In addition, although the embodiments described herein are directed to a combination outer stop with shrouding and filter features for a data storage device, it will be appreciated by those skilled in the art that the combination outer stop with shrouding and filter features can be used for other types of storage devices, including optical drives and magneto-optical drives, without departing from the spirit and scope of the claimed invention.