Patent Publication Number: US-6985430-B1

Title: Transducer positioning device

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to transducer positioning devices for media drives. 
   2. Background Art 
   Transducer positioning devices are used in media drives to align a transducer with respect to a media track or tracks. Examples of transducer positioning devices are disclosed in U.S. Pat. No. 6,437,946. 
   SUMMARY OF THE INVENTION 
   Under the invention, a transducer positioning apparatus includes a frame, a first carriage movably associated with the frame and having a guide member, a second carriage that is movable with respect to the guide member between multiple positions relative to the guide member, and a transducer mounted on the second carriage. An anti-rotation member is associated with the second carriage for inhibiting rotational movement of the second carriage as the second carriage moves with respect to the guide member. The apparatus further includes an actuator associated with the second carriage. The actuator is operative to move the second carriage with respect to the guide member to a selected position of the multiple positions and to move the first carriage and the second carriage relative to the frame to locate the transducer in a desired position. 
   Further under the invention, a transducer positioning apparatus includes a frame, a flexible member attached to the frame, and a guide member suspended from the frame by the flexible member. A carriage with a transducer mounted thereon is movable with respect to the guide member between multiple positions relative to the guide member. The apparatus further includes an actuator associated with the carriage. The actuator is operative to move the carriage with respect to the guide member to a selected position of the multiple positions and to move the carriage and the guide member relative to the frame to locate the transducer in a desired position. Furthermore, the flexible member is configured to allow axial movement of the guide member while inhibiting rotational movement of the guide member. 
   Still further under the invention, a transducer positioning apparatus includes a fixed frame and first and second spring members that each have first and second ends attached to the fixed frame. A first carriage is suspended from the fixed frame by the spring members and includes an elongated main guide member and a first anti-rotation member. A second carriage having a transducer mounted thereon is movably associated with the first carriage such that the second carriage is movable along the main guide member between multiple positions relative to the main guide member. The second carriage includes a second anti-rotation member that cooperates with the first anti-rotation member to inhibit rotation of the second carriage as the second carriage moves along the main guide member. The apparatus also includes an actuator associated with the second carriage and operative to move the second carriage along the main guide member to a selected position of the multiple positions. The actuator is further operative to move the first carriage and the second carriage relative to the fixed frame when the second carriage is in the selected position relative to the main guide member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a transducer positioning apparatus according to the invention for use with a media drive, wherein the apparatus includes a fixed frame, first and second carriages movably associated with the fixed frame, a transducer mounted on the second carriage, and an actuator associated with the second carriage for positioning the transducer; 
       FIG. 2  is a perspective view of the carriages and transducer of the apparatus of  FIG. 1 ; 
       FIG. 3  is a side view of the carriages and transducer of  FIG. 2 ; and 
       FIG. 4  is a schematic view of the first carriage suspended from the fixed frame by a pair of constrained flexible members. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     FIG. 1  shows a transducer positioning apparatus  10  according to the invention for use with a media drive, such as a tape drive or disc drive. The apparatus  10  includes a frame, such as a fixed frame  12 , first and second carriages  14  and  16 , respectively, movably associated with the fixed frame  12 , a transducer  18  mounted on the second carriage  16 , and an actuator  20  associated with the second carriage  16  for locating the transducer  18  in a desired position, as explained below in detail. 
   The fixed frame  12  is configured to be attached to a drive body (not shown) of the media drive, such that the fixed frame  12  remains stationary with respect to the drive body. For example, a lower portion  21  of the fixed frame  12  may be attached to the drive body with fasteners, such as screws. 
   The first carriage  14  is suspended from the fixed frame  12  with one or more flexible spring members  22 , such as leaf springs. In the embodiment shown in  FIGS. 1–3 , the apparatus  10  includes two spring members  22  that are each fixedly attached at each end to the fixed frame  12 , with fasteners for example, such that the spring members  22  are constrained at their ends. Central portions of the spring members  22  are attached to the first carriage  14  proximate opposite ends of the first carriage  14 . Furthermore, the spring members  22  may be configured to allow movement of the first carriage  14  with respect to the fixed frame  12 . For example, each spring member  22  may include bent portions  23 , such as folds and/or radiused bends, that lengthen upon flexing of the spring member  22 . With the configuration described above, the spring members  22  may allow translation of the first carriage  14 , while inhibiting rotational movement of the first carriage  14 . 
   Referring to  FIGS. 1–3 , the first carriage  14  includes a first carriage body  24 , such as an outer carriage body, and one or more first guide members  26  attached to the first carriage body  24  for guiding movement of the second carriage  16 . While the first guide member  26  may comprise any suitable guide element or elements, such as bearings, bushings and/or rails, in the embodiment shown in  FIGS. 1–3 , the first guide member  26  comprises a guide track or rod fixedly attached to the first carriage body  24 . The first guide member  26  also has an axis  27  along which the second carriage  16  may move. 
   Furthermore, the first carriage body  24  and/or first guide member  26  may be fixedly secured to each spring member  22 . For example, the first carriage body  24  and/or first guide member  26  may be joined to each spring member  22  with a swage joint. As another example, the first carriage body and/or first guide member  26  may be press fit, welded and/or adhesively bonded to each spring member  22 . Thus, the first guide member  26  may be attached directly or indirectly to the spring members  22  such that the first guide member  26  is suspended by the spring members  22 . 
   With the configuration described above, the spring members  22  may allow movement of the first carriage  14  in a direction generally parallel to the axis  27 , while inhibiting rotational movement of the first carriage  14  about the axis  27  as well as any axis generally perpendicular to axis  27 . Referring to  FIG. 4 , for example, the spring members  22  may allow translation of the first carriage  14  in a direction generally parallel to the axis  27  between a first position shown in solid lines and a second position shown in phantom lines, while inhibiting rotational or twisting movement of the first carriage  14 . 
   Returning to  FIGS. 1–3 , the second carriage  16  includes a second carriage body  28 , such as an inner carriage body, and one or more second guide members  30  attached to the second carriage body  28  for guiding movement of the second carriage body  28 . While each second guide member  30  may comprise any suitable guide element or elements, such as rods, tracks and/or rails, in the embodiment shown in  FIGS. 1 and 2 , the second guide members  30  comprise two guide bearings or bushings, such as jewel bearings, that are slidable along the first guide member  26 . Moreover, the second carriage  16  is movable with respect to the first carriage  14  between multiple positions relative to the first carriage  14 . 
   The transducer  18  is fixedly mounted on the second carriage  16  such that the transducer  18  is movable with the second carriage  16 . Moreover, the transducer  18  may comprise a read transducer, a write transducer, or any combination thereof, such that the transducer  18  may perform read and/or write operations on media, such as tape or discs. 
   The actuator  20  may comprise any suitable device sufficient to move the second carriage  16  to a selected position of the multiple positions relative to the first carriage  14 , and to move the first carriage  14  and the second carriage  16  relative to the fixed frame  12  to locate the transducer  18  in a desired position relative to data written on media. For example, the actuator  20  may comprise a first actuator portion  32 , such as a voice coil, attached to the second carriage body  28 , and a second actuator portion  34 , such as a magnet assembly, attached to the fixed frame  12 . When energized, the second actuator portion  34  is operative to induce movement of the first actuator portion  32  and the second carriage  16  relative to the second actuator portion  34 . 
   The apparatus  10  may also include one or more anti-rotation members for inhibiting rotational movement of the second carriage  16  with respect to the first carriage  14 . For example, the apparatus  10  may include first and second anti-rotation members  36  and  38 , respectively, such as rods, rails, tracks and/or bearings, that cooperate with each other to inhibit rotational movement of the second carriage  16 . In the embodiment shown in  FIGS. 1–3 , the first anti-rotation member  36  includes a bearing or bushing attached to the first carriage body  24 , and the second anti-rotation member  38  includes a rod attached to the second carriage body  28 . As the second carriage  16  moves with respect to the first carriage  14 , the first anti-rotation member  36  allows sliding movement of the second anti-rotation member  38 , while inhibiting rotational movement of the second carriage  16  about axis  27 . As another example, the first anti-rotation member  36  may comprise a rod or rail, and the second anti-rotation member  38  may comprise a bearing or bushing that slides along the first anti-rotation member  36 . 
   Alternatively or supplementally, the carriage bodies  24  and  28  may define anti-rotation members. For example, the first carriage body  24  may include a channel  39  configured to slidably receive a portion of the second carriage body  28  and to inhibit rotational movement of the second carriage body  28 . As another example, the second carriage body  28  may include a channel that slides along a portion of the first carriage body  24 . 
   Furthermore, the apparatus  10  may be configured to inhibit movement of the second carriage  16  with respect to the first carriage  14  when the second carriage  16  has achieved a desired or selected position relative to the first carriage  14 . For example, the apparatus  10  may include a mechanical locating system  40 , such as a detent mechanism and/or linkage/spring system, for holding the second carriage  16  in a desired discrete position relative to the first carriage  14 . 
   In the embodiment shown in  FIG. 1 , the mechanical locating system  40  is configured as an over-the-center linkage/spring system that includes a link  42  pivotally connected to the first carriage  14  and engageable with the guide member  26 , and a spring  44  pivotally connected to the link  42  and engageable with the second carriage  16 . The link  32  may be pivotally connected to the first carriage  14  at aperture  45 , for example, which is shown in  FIGS. 2 and 3 . When the actuator  20  applies a force on the second carriage  16 , the spring members  22  may flex, thereby allowing axial movement of the carriages  14  and  16 , until the force exerted by the spring members  22  on the first carriage  14  is greater than the retarding force exerted by the mechanical locating system  40 . At that point, the mechanical locating system  40  may allow movement of the second carriage with respect to the guide member  26 . For example, the spring  44  may slide along the second carriage  16 , thereby allowing the second carriage  16  to slide along the guide member  26  until the second carriage  16  reaches a desired position relative to the guide member  26 . During this process, the link  42  and/or spring  44  of the mechanical locating system  40  may pivot, thereby affecting the force exerted by the link  42  and/or spring  44  on the guide member  26  and/or second carriage  16 . When the second carriage  16  reaches the desired position, the mechanical locating system  40  may be used to maintain the second carriage  16  in that position. 
   As another example, the apparatus  10  may be provided with a stop for inhibiting movement of the first carriage  14  in order to allow the second carriage  16  to move with respect to the first carriage  14 . For example, a set screw  46  may be inserted into an aperture  48  of the fixed frame  12  to define a stop for the first carriage  14 . When the first carriage  14  engages the screw  46 , the mechanical locating system  40  may then allow the second carriage  16  to move with respect to the first carriage  14 . 
   As yet another example, the mechanical locating system  40  may be configured as a detent mechanism such as disclosed in U.S. Pat. No. 6,437,946, which is hereby incorporated by reference in its entirety. Such a detent mechanism may be disposed between the carriages  14  and  16  and include an engaging member, such as a click, that selectively engages multiple notches or recesses to selectively position the second carriage  16  with respect to the first carriage  14 . 
   Alternatively or supplementally, the apparatus  10  may be configured such that friction forces between the carriages  14  and  16  function to inhibit movement of the second carriage  16  with respect to the first carriage  14  when the second carriage  16  is in a desired position relative to the first carriage  14 . For example, friction forces between the guide members  26  and  30  and/or between the anti-rotation members  36  and  38  may function to hold the second carriage  16  in a desired position relative to the first carriage  14 . 
   Operation of the apparatus  10  will now be described in detail. First, the actuator  20  may be used to coarsely position the transducer  18 , such as within an appropriate band of tracks on a tape or disk. More specifically, referring to  FIG. 1 , the actuator  20  may be used to slide the second carriage  16  along the first guide member  26 . As mentioned above, the first carriage  14  may initially move with the second carriage  16  until the retarding force of the mechanical locating system  40  and/or friction forces between the carriages  14  and  16  are exceeded. Upon reaching a selected position relative to the first carriage  14 , the mechanical locating system  40  and/or friction forces between the carriages  14  and  16  may be used to hold the second carriage  16  in the selected position. 
   Next, the actuator  20  may be used to finely position the transducer  18 , such as with respect to a particular track or tracks. More specifically, the actuator  20  may be used to move the carriages  14  and  16  with respect to the fixed frame  12 , while the second carriage  16  is maintained in the selected position relative to the first carriage  14 . Because each spring member  22  is constrained at each end, the spring members  22  allow movement of the carriages  14  and  16  with respect to the fixed frame  12  in a direction generally parallel to the axis  27 , while inhibiting rotational movement of the carriages  14  and  16 . 
   With the configuration described above, the carriages  14  and  16  and the first actuator portion  32  cooperate to form at least part of a suspended mass that is suspended by the spring members  22 . While not required, the center of mass of the suspended mass may be generally axially aligned with the axis  27 , thereby reducing unwanted motion or resonances due to forces internal and external to the apparatus  10 . 
   Furthermore, the position of the transducer  18  relative to the second guide members  30  may inhibit rotational movement of the second carriage  16  relative to the first carriage  14 . Referring to  FIGS. 2 and 3 , for example, the transducer  18  may be positioned such that a plane  50  bisecting the transducer  18  extends between the second guide members  30  and generally perpendicular to the axis  27 . The plane  50  also extends between opposite ends of each of the carriages  14  and  16 . With such a configuration, twisting of the second carriage  16  relative to the first carriage  14  may be reduced or eliminated as media, such as tape, travels over the transducer  18 . As shown in  FIG. 2 , the direction of travel  52  of media across the transducer  18  may be generally perpendicular to the axis  27 . 
   While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. For example, the first guide member of the first carriage may be configured as one or more bearings, and the second guide member of the second carriage may be configured as a rod, track or rail that is slidable along the first guide member. As another example, while the apparatus shown in the Figures is configured for use with a tape drive, an apparatus according to the invention may instead be configured for use with a disc drive.