Abstract:
An apparatus for unloading a moveable member comprises a ramp structure with an inclined surface. A lift tab of the moveable member advances along the ramp structure to the inclined surface while pivoting about a pivot point to undergo an increase in elevation above a base surface. The inclined surface has a slope determined in relation to angular deflection of the lift tab induced by said increase in elevation. Preferably, the slope of the inclined surface substantially matches an angle of the lift tab when the lift tab is disposed on the inclined surface. The inclined surface preferably constitutes a parking surface, and the ramp structure further preferably comprises an entry/exit ramp surface and a latch surface along which the lift tab travels to reach the parking surface. The moveable member preferably comprises a flexible suspension which supports a transducer adjacent a data storage medium in a data storage device.

Description:
FIELD OF THE INVENTION 
     The claimed invention relates generally to the field of actuated systems and more particularly, but not by way of limitation, to a ramp structure with an inclined contact surface to support a transducer in an unloaded position. 
     BACKGROUND 
     The ongoing commercialization of digital data processing devices has generally resulted in successive generations of devices having ever higher rates of functionality and interconnectivity. To this end, mass storage capabilities are being increasingly incorporated into a number of different types of devices, particularly with hand-held portable devices such as cell phones, digital cameras, personal data assistants (PDAs), etc. 
     A disc drive is a type of mass storage device that generally stores data on one or more rotatable magnetic recording discs. A corresponding array of data transducers (heads) is selectively moved across the surfaces of the discs to transduce data therewith. During periods of device non-use, the transducers can be unloaded from the media to a safe parked position, such as upon a ramp structure disposed adjacent a peripheral edge of the media. 
     While a variety of ramp load/unload structures have been proposed in the art for use in disc drives and other types of devices, there remains a continual need for improvements that promote increased functionality and reliability, particularly in high vibration and mechanical shock environments. It is to these and other improvements that preferred embodiments of the present invention are generally directed. 
     SUMMARY OF THE INVENTION 
     Preferred embodiments of the present invention are generally directed to an apparatus for unloading a moveable member. 
     In accordance with preferred embodiments, a ramp structure is provided having an inclined surface. A lift tab of the moveable member advances along the ramp structure to the inclined surface while pivoting about a pivot point to undergo an increase in elevation above a base surface. The inclined surface has a slope determined in relation to angular deflection of the lift tab induced by said increase in elevation. 
     Preferably, the slope of the inclined surface substantially matches an angle of the lift tab when the lift tab is disposed on the inclined surface. The inclined surface preferably constitutes a parking surface, and the ramp structure further preferably comprises an entry/exit ramp surface and a latch surface along which the lift tab travels to reach the parking surface. The entry/exit ramp surface and the latch surface are likewise preferably provided with respective inclines selected in relation to elevational deflection of the lift tab. 
     The moveable member preferably comprises a flexible suspension which supports a transducer adjacent a data storage medium in a data storage device. In this way, the ramp structure serves to facilitate loading and unloading of the transducer to and away from the medium. 
     These and various other features and advantages that characterize the claimed invention will be apparent upon reading the following detailed description and upon review of the associated drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a disc drive block data storage device constructed and operated in accordance with preferred embodiments of the present invention. 
         FIG. 2  shows relevant portions of the actuator of  FIG. 1 , including a suspension lift tab that interfaces with the ramp structure of  FIG. 1 . 
         FIG. 3  provides a side elevational view of relevant portions of the ramp structure of  FIG. 1  to illustrate incorporation of an inclined contact surface in accordance with preferred embodiments. 
         FIG. 4  shows a top plan view of the ramp structure of  FIG. 3 . 
         FIG. 5  shows a cross-sectional representation of a park zone of the ramp structure of  FIG. 3  as generally viewed along line  5 - 5  in  FIG. 3 . 
         FIG. 6  shows a cross-sectional representation of a latch zone of the ramp structure of  FIG. 3  as generally viewed along line  6 - 6  in  FIG. 3 . 
         FIG. 7  shows a cross-sectional representation of an entry/exit zone of the ramp structure of  FIG. 3  as generally viewed along line  7 - 7  in  FIG. 3 . 
         FIG. 8  shows a preferred application of texturing to the ramp structure. 
         FIG. 9  provides an alternative embodiment of the ramp structure that employs planar curvilinear surfaces. 
         FIG. 10  provides a schematic diagram to further illustrate the preferred manner in which an inclined surface of the ramp structure has a slope determined in relation to angular deflection of the lift tab induced by an increase in elevation as the lift tab is radially advanced to the inclined surface. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings,  FIG. 1  provides a top plan view of a disc drive block data storage device  100 . The drive  100  is provided to show an exemplary environment in which preferred embodiments of the present invention can be advantageously practiced. It will be understood, however, that the claimed invention is not so limited. 
     The device  100  includes a substantially sealed housing  102  formed from a base deck  104  and top cover  106 . An internally disposed spindle motor  108  is configured to rotate a number of storage media  110 . The media  110  are accessed by a corresponding array of data transducers  112 . While  FIG. 1  shows the use of two magnetic recording discs and four corresponding heads, other numbers of heads and discs (such as a single disc, etc.) and other types of media (such as optical media, etc.) can alternatively be utilized as desired. 
     A head-stack assembly (“HSA” or “actuator”) is shown at  114 . Each transducer  112  is preferably supported by a corresponding flexible suspension  116 , which in turn is supported by a rigid actuator arm  118 . The actuator  114  preferably pivots about a cartridge bearing assembly  120  through application of current to a voice coil motor (VCM)  122 . In this way, controlled operation of the VCM  122  causes the transducers  122  to align with tracks (not shown) defined on the media surfaces to store data thereto or retrieve data therefrom. 
       FIG. 1  further shows a flex circuit assembly  124  that facilitates electrical communication between the actuator  114  and device control electronics on an externally disposed device printed circuit board (PCB)  126 . The flex circuit assembly  124  includes VCM signal paths to accommodate the application of current to the VCM  122 . The flex circuit assembly  124  further provides I/O signal paths to accommodate the transfer of write data to be written by the transducers  112 , and readback data obtained by the transducers during a read operation. 
     When the device  100  is not in use, the transducers  112  are preferably moved (unloaded) to a ramp structure  130  located near an outermost periphery of the media. The ramp structure  130  serves to provide respective surfaces on which the transducers  112  can safely be disposed while the media  110  are in a non-rotational state. When device I/O operation is desired, the spindle motor  108  accelerates the media  110  to a velocity sufficient to support the transducers  112 , and the transducers  112  are moved (loaded) from the ramp structure  124  to the media  110 . 
       FIG. 2  illustrates relevant portions of one of the flexible suspensions  116  of  FIG. 1  in greater detail. For reference,  FIG. 2  is an underside view of the topmost suspension  116  shown in  FIG. 1 . 
     The suspension  116  is shown to preferably include a load beam  132  which extends from a base  134 . The base  134  is preferably attached to the distal end of the corresponding actuator arm  118  using adhesive or other suitable attachment mechanism. Support tabs  136  extend from the base  134  to support flex on suspension (FOS) conductors used to route signal paths from the transducer  112  to the flex circuit assembly  124 . 
     The transducer  112  is gimbaled near a distal end of the load beam  132 , and includes a slider structure (not separately designated) configured to hydrodynamically interact with a flow of fluidic currents established by high speed rotation of the media  110 . In this way, the transducer  112  is maintained upon a stable bearing surface in close proximity to the media  110 . 
     The load beam  132  is preferably characterized as a spring and is biased in a direction toward the corresponding media surface. A lift tab  138  projects from the distal end of the load beam  132  as shown. While a variety of relative angular orientations can be provided for the lift tab  138  with respect to the load beam  132 , in a preferred embodiment the lift tab  138  is arranged to as to be substantially parallel to the media  110  when the transducer  112  is supported thereover during I/O operation. 
     The lift tab  138  is configured to engage the ramp structure  130  during head load/unload operations as explained below. At this point it will be noted that placement of the lift tab  138  at the distal end of the load beam  132  is preferred, but not required; rather, the lift tab  138  can be placed at any number of suitable locations along the length of the load beam  132  as desired. The lift tab  138 , as well as the load beam  132 , are preferably formed of stainless steel or other suitable material. 
     As will be recognized, prior art ramp load/unload systems have been proposed in the art which generally provide a point contact between the lift tab and the corresponding ramp surfaces. While operable, a limitation with these and other approaches is the undesired wear of the ramp surface along the leading edge/corner of the ramp structure. Over time, this can lead to undesired particulate generation within the device, as well as changes in the static and dynamic friction forces encountered by the lift tab as it traces a path along the ramp structure. 
     Accordingly, preferred embodiments of the present invention provide the ramp structure  130  with one or more inclined surfaces, such as generally shown in  FIG. 3 . More particularly,  FIG. 3  provides an elevational representation of relevant portions of the ramp structure  130  with opposing ramp structures to accommodate the associated transducers  112  adjacent the recording surfaces of a first medium  110  in  FIG. 1 . It will be understood that a second structure nominally identical to that shown in  FIG. 3  is provided to accommodate the transducers  112  for the second medium  110  of  FIG. 1 .  FIG. 4  provides a corresponding top plan view of the structure  130  in  FIG. 3 . 
     The ramp structure  130  is preferably formed of injected molded plastic or similar material with relatively low wear characteristics. The ramp structure preferably includes a central body portion  140  with opposing ramped entry/exit surfaces  142 , latch surfaces  144 , transitional surfaces  146 , and parking surfaces  148 . Each of these surfaces is preferably inclined (sloped) with respect to the associated media surface in relation to an elevational height above or below the associated media surface. 
     During an unload operation, the transducers  112  are moved outwardly toward the ramp structure  130  so that the lift tabs  138  contactingly travel along the respective surfaces  142 ,  144  and  146  and come to rest upon the parking surfaces  148 . The transitional surfaces  146  and limit stop surfaces  150  preferably serve to retain the lift tabs  138  within the radial range of the parking surfaces  148  when the device  100  is deactivated. An additional latching mechanism, such as a magnetic latch (not shown) adjacent the VCM  122  is preferably used to retain the actuator  114  in the latched (unloaded) position. 
     It will be appreciated that any number of suitable shapes and arrangements for the respective zones of the ramp structure  130  can be utilized as desired, including a ramp structure that curvilinearly extends along a rotational path of travel of the lift tabs  138 . Similarly, the angles of incline shown in  FIG. 3  are somewhat exaggerated for clarity of illustration and can be selectively provided as dictated by the requirements of a given application. 
     Channel surfaces  152  are preferably provided within the body  140  to receivingly nest an outermost peripheral edge of the medium  110 . This allows the entry/exit ramp surfaces  142  to extend out over the media surfaces as shown to ensure reliable transition of the transducers from the media  110  to the ramp structure  130 . At the same time, the entry/exit ramp surfaces  142  are preferably placed as near as practical to the outermost peripheral edges of the media  110  to increase the available media recording area. 
     As mentioned above, the respective surfaces  142 ,  144 ,  146  and  148  are preferably inclined with respect to the media surfaces. A preferred inclined orientation for the parking surfaces  148  is represented in  FIG. 5 , which shows a cross-sectional depiction of the ramp structure  130  taken along line  5 - 5  in  FIG. 3 . 
     As represented in  FIG. 5 , the parking surfaces  148  are configured so as to be nominally parallel to the lift tabs  138  when the lift tabs  138  come to rest thereon. The incline, as depicted by angle θ 1 , will preferably match the angle of the lift tab  138  at this point, and can be, for example, on the order of a few degrees. This helps to ensure that contact between the lift tab  138  and the ramp structure  130  is established along the parking surface  148  and is not localized along corner edge surfaces  154 . 
       FIG. 6  provides a corresponding cross-sectional view of the ramp structure  130  along lines  6 - 6  in  FIG. 3  to show a preferred orientation of the latch surfaces  144 . While the latch surfaces  144  can be provisioned with the same angular incline as the parking surfaces  148 , or even with no angular incline at all, preferably the latch surfaces  144  have a greater incline as measured by angle θ 2 , with θ 2 &gt;θ 1 . As before, the angle θ 2  is preferably selected so that the lift tabs  138  will be substantially parallel to the surfaces  144  as the lift tabs travel thereacross, thereby increasing the consistency of the tab/surface interface and reducing point contact along corner surfaces  156 . 
     The entry/exit ramp surfaces  142  are generally depicted in  FIG. 7 , which provides a cross-sectional view as taken along line  7 - 7  in  FIG. 3 . The ramp surfaces  142  preferably continuously transition from substantially no incline at the beginning of the ramp adjacent the medium  110 , up to the incline θ 2  of the latch surfaces  144 . At the intermediary point at which the cross-section of  FIG. 7  is taken, the ramp surfaces  142  are shown to preferably exhibit an incline angle of θ 3 , with θ 3 &lt;θ 2 . Although not separately shown, it will be understood that the transition surfaces  146  preferably transition in similar fashion between θ 2  and θ 1 . 
     The ramp surfaces can be texturized or otherwise prepared to provide a better and more consistent frictional characteristic for the lift tabs  138 . An example of such texturizing is illustrated in  FIG. 8  by a series of detents  158  provided to the parking surface  148 . 
     While the inclined surfaces have been shown to be preferably characterized as planar linear surfaces, such is not necessarily required. Rather, the surfaces can alternatively be inclined planar curvilinear surfaces, such as exemplified in  FIG. 9 . As before, the surfaces  148  shown in  FIG. 9  are inclined to substantially match the incline of the lift tabs  138 . 
     For clarity,  FIG. 9  further illustrates a base support member  160  to better illustrate a preferred manner in which the surfaces  148  of  FIG. 9 , as well as the ramp surfaces shown in  FIGS. 3-7 , are preferably supported. The base support member  160  preferably engages the base deck  102  and extends substantially normal thereto. The various inclined surfaces discussed herein can thus be characterized as being skewed (e.g., non-normal) with respect to the base support member  160 . 
     It can now be seen that the angle of incline of the various ramp surfaces will preferably be determined in view of the simple geometric relationship between the distance from the top surface of the ramp to the lift tab bottom and load beam length. More specifically, as illustrated by  FIG. 10 , the lift tab  138  starts at a first position at a first elevation E 1  adjacent a base surface (e.g., the associated medium  110 ), and contactingly advances along the ramp structure  130  to a second position at a second elevation E 2  on the associated inclined surface (e.g., parking surface  148 ). The incline of the surface is preferably determined with respect to pivot point  162  (e.g., base  134 ,  FIG. 2 ) as the lift tab  138  moves from E 1  to E 2 . 
     The use of inclined ramp surfaces as exemplified herein provides several advantages over the prior art. The actual paths taken by the lift tabs  138 , even in the case of a point contact, can be more closely controlled and ensured to follow along the surfaces of the ramp structure (e.g.,  142 ,  144 ,  146 ,  148 ) rather than along the edges (e.g.,  154 ,  156 ). As the edges have been found to be difficult to produce accurately in certain types of molding processes, the above preferred configurations reduce or eliminate the likelihood that contact will take place between the edges of the ramps and the load tabs. 
     The inclined surfaces also generally increase the types of lift tab configurations that can be utilized; for example, a generally cylindrical load tab can be used, as well as one with a detent or other contact feature. 
     Moreover, while preferred embodiments discussed herein have placed the incline to substantially match that of the lift tabs, this is not necessarily required; rather, it can be readily seen that other angular configurations, including inclines of the ramp surfaces that are greater than the angle of the lift tabs, can also be used as desired to improve the advancement path between the lift tabs and the ramp structures and to accommodate manufacturing tolerances. 
     Finally, while preferred embodiments have been directed to transducer loading/unloading in a data storage device, it will be appreciated that the claimed invention can readily be utilized in any number of other applications, including non-data storage device applications. 
     It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various 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 in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application without departing from the spirit and scope of the present invention.