Abstract:
A data storage apparatus and associated method is provided involving a data storage disc that is rotatable around a first axis. An actuator is rotatable around a second axis to operably position a data transfer member between an innermost radial location of the data storage disc and an outermost radial storage location of the data storage disc. A snubber is supported by the actuator and has a distal edge configured as being, in relation to a reference plane including the first axis and the second axis when the actuator is rotated to position the data transfer member at the innermost radial location, arcuate along a first radius on one side of the reference plane and arcuate along a second radius different than the first radius on the other side of the reference plane.

Description:
SUMMARY 
     In some embodiments a data storage device is provided having a data storage disc that is rotatable around a first axis. An actuator is rotatable around a second axis to operably position a data transfer member between an innermost radial location of the data storage disc and an outermost radial storage location of the data storage disc. A snubber is supported by the actuator and has a distal edge configured as being, in relation to a reference plane including the first axis and the second axis when the actuator is rotated to position the data transfer member at the innermost radial location, arcuate along a first radius on one side of the reference plane and arcuate along a second radius different than the first radius on the other side of the reference plane. 
     In some embodiments an actuator for a data storage device is provided having a data storage disc that is rotatable around a first axis. The actuator has an actuator body that is rotatable around a second axis to operably position a data transfer member between an innermost radial location of the data storage disc and an outermost radial storage location of the data storage disc. A snubber is supported by the actuator and has a distal edge configured, in relation to a reference plane including the first axis and the second axis when the actuator is rotated to position the data transfer member at the innermost radial location, on one side of the reference plane as being concave to the second axis and disposed between an outer edge of the data storage disc and the outermost radial storage location, and on the other side of the reference plane as being non-concave to the second axis and disposed between the outer edge of the data storage disc and the outermost radial storage location. 
     In some embodiments a method is provided including obtaining an actuator for a data storage device having a data storage disc that is rotatable around a first axis. the actuator having an actuator body that is rotatable around a second axis to operably position a data transfer member between an innermost radial location of the data storage disc and an outermost radial storage location of the data storage disc, and a snubber supported by the actuator and having a distal edge configured, in relation to a reference plane including the first axis and the second axis when the actuator is rotated to position the data transfer member at the innermost radial location, on one side of the reference plane as being concave to the second axis and disposed in an annulus between an outer edge of the data storage disc and the outermost radial storage location, and on the other side of the reference plane as being non-concave to the second axis and disposed between the outer edge of the data storage disc and the outermost radial storage location. The method further includes rotating the actuator to move the data transfer member to a first radial storage location where only the distal edge on the one side of the reference plane is within the annulus, and rotating the actuator to move the data transfer member to a second radial storage location where the distal edge on the other side of the reference plane is within the annulus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  diagrammatically depicts a top cutaway view of a data storage device that is constructed in accordance with embodiments of the present invention. 
         FIG. 2  is an isometric depiction of the actuator of the data storage device of  FIG. 1 . 
         FIG. 3  is a cross sectional view of a portion of the actuator of  FIG. 2 . 
         FIG. 4  is a simplified depiction of a portion of the data storage device of  FIG. 1 . 
         FIG. 5  is an enlarged detail view of a portion of the data storage device of  FIG. 4 . 
     
    
    
     DESCRIPTION 
     Disc drive data storage devices are all the time becoming more commonly used in portable systems having onboard processing systems that are by nature of application subjected to random movement and vibration. A disc drive stores data that must be readily available to a user regardless of the use. Generally, a disc drive has one or more rotating data storage discs in a data transfer relationship with a rotating actuator that moves a data transfer member in a close mating relationship with the discs. 
     Consumer demands have continually pushed the industry to provide more capacity in a smaller-size package. Those demands necessarily require smaller spacing between the actuator and the data storage discs, and more precise positioning of the actuator relative to the data storage discs. Although meeting these demands, the tight spacing of the data storage discs gives rise to a problem of increased sensitivity of the disc drives to non-operating, mechanical shocks; particularly. predominant failure modes in modern disc drives have been found to include damage to the surfaces of the discs and damage to the actuator arms as a result of mechanical shocks encountered during the shipping, handling, and portable use of the data storage devices. 
     Computer modeling of particular disc drives has revealed that one primary cause of interference between discs and actuator arms is the first mechanical bending mode of the discs, which has been found to cause a significant portion of the relative motion between the data storage discs and the actuator. The bending mode is generally dependent upon the material, diameter and thickness of the data storage discs, and these factors are not readily modified in a disc drive design. 
     Turning now to the drawings collectively and now more particularly to  FIG. 1 , shown therein is a top view of a data storage device  100  that is constructed in accordance with embodiments of the present invention. The device  100  includes a base  102 , to which various disc drive components are mounted, and a cover  104  (shown partially cutaway), which cooperates with the base  102  to provide a sealed internal environment for the device  100 . 
     Mounted to the base  102  is a spindle motor (shown generally at  106 ) to which one or a plurality of data storage discs  108  are mounted for rotation at a high speed around a first axis  109 . Adjacent the discs  108  is an actuator  110  which is pivoted around a second axis  112 , such as by a voice coil motor  113 . The actuator  110  includes a number of arms  114 , one per each disc recording surface, supporting suspensions  116  that, in turn, support data transfer members  118 . As such, the data transfer members  118  are selectively positioned with respect to data tracks (only one outermost track  120  depicted diagrammatically) of the discs  108  in order to read data from and write data to the tracks. 
     The data transfer members  118  are selectively moved between an innermost radial location  122  and the outermost radial storage location  120 . In these illustrative embodiments the innermost radial location is an annulus of disc space that is not used for storing data, but is rather a landing space upon which the data transfer member  118  can be parked when the device  100  is shut down or switched to a reduced power mode. In alternative equivalent embodiments the innermost radial location can be an innermost data track, with the landing zone being elsewhere such as a landing ramp beyond the outer edge  126  of the disc  108 . Also in these illustrative embodiments between the outermost radial storage location  120  and the outer edge  126  of the disk  108  there is another annulus of non-storage space  128 . The non-storage space  128  provides a guard band from the disc edge  126  where fluidic turbulence creates data transfer member  118  positional fluctuations of a magnitude greater than that which facilitates reliable data transfer activity. 
       FIG. 2  is an isometric depiction of an actuator  110  of the present embodiments suited for use with up to a four-disc stack, wherein two discs  108  can be operably interleaved in spaces between each pair of adjacent arms  114 , and two discs  108  can be operably disposed outside the outermost arms  114 . As the arms  114  move in close relationship to the respective disc surface, an external shock can cause the disc  108  to deflect and contactingly engage the respective arm  114 , likely causing damage to the disc  108  or the arm  114  or both. To prevent that damage, snubbers  130  are provided on each of the arms  114  that are sized to contactingly engage the non-data storage space  128 , thereby preventing a contacting engagement between an arm  114  and the storage space of the respective disc surface. 
       FIG. 3  is an enlarged cross sectional view of the actuator  110  of  FIG. 3  and four operably engaged discs  108 . Note that each arm  114  defines a surface that is substantially parallel to the respective disc surface and spatially separated therefrom by a clearance that prevents operable contacting engagement in normal circumstances. Each snubber  130  likewise defines a surface that is substantially parallel to the respective disc surface and spatially separated therefrom by a smaller clearance. Note that each snubber  130  has a distal edge  132  encroaching inwardly past the disc edge  126  only within the non-storage space annulus  128 . Thus, the smaller clearance between the snubber  130  and respective disc surface means a disc  108  deflection will result in any contact being with only the non-storage area  128  of the disc  108 , preventing the damage to disc storage space or stored data on the disc  108 . To minimize weight, and hence inertia, the actuator  110  and snubber  130  are unitarily constructed, such as of aluminum. 
       FIG. 4  is a simplified depiction of the actuator  110  when it is pivoted to position the data transfer member (not shown) at the innermost radial location, be it an innermost radial storage location or a landing zone. The present embodiments optimize the structural integrity of the snubber  130  by sizing it to be as large as possible; that is, to fill the entire portion of the annulus of non-storage space  128  that the actuator  110  encroaches in the position depicted in  FIG. 4 . That snubber  130  construction ensures an even distribution of force by the snubber  130  in stopping the impacting disc  108 , the force thereby acting across as broad a circumferential portion of the disc edge  126  as possible. The evenly distributed snubbing force advantageously minimizes the resonant response of the disc  108  resulting from impact. 
     At this depicted extent of the depicted counter-clockwise actuator  110  rotation, a reference plane  134  is constructed passing through the first axis  109  and the second axis  112 .  FIG. 5  is an enlarged detail view showing how the snubber  130  of the present embodiments is constructed in terms of the size of the annulus of non-storage space  128  and disposition of the intersecting reference plane  134 . 
     A radius  136  centered at the second axis  112  is tangent to a radial edge  138  of the annulus of non-storage space  128 . A portion of the radius  136  defines a concave edge  132   a  of the snubber  130  (concave to the second axis  112 ) on the right-hand side of the reference plane  134  in these illustrative embodiments. The configuration of the portion of the snubber  130   a  on the right-hand side of the reference plane  134  is thereby depicted by the slanted hatching pattern in  FIG. 5 . 
     Letting the radius  136  define the edge of the snubber  130  on the left-hand side of the reference plane  134  would not be in keeping with maximizing the size of the snubber  130 , and as such would not be in accordance with the embodiments of the present invention. Rather, in these illustrative embodiments the radial edge  138  defines a non-concave edge (to the second axis  112 ), or more particularly in these illustrative embodiments a convex edge  132   b  of the snubber  130  (convex to the second axis  112 ) on the left-hand side of the reference plane  134 . The configuration of the portion of the snubber  130   b  on the left-hand side of the reference plane  134  is thereby depicted by the cross hatching pattern in  FIG. 5 . The resulting configuration of the snubber  130  is defined, with respect to the second axis  112 , by a concave first radius on one side of the reference plane and a convex second radius different than the first radius on the other side of the reference plane. 
     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 and values for the described variables, within the principles of the present embodiments to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.