Patent Publication Number: US-10789980-B2

Title: Attenuating reaction forces caused by externally supported stators in brushless DC motors

Description:
BACKGROUND 
     The present invention relates to magnetic tape drives, and more particularly, this invention relates to attenuating reaction forces in magnetic tape drive motors. 
     In magnetic storage systems, magnetic transducers read data from and write data onto magnetic recording media. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media. 
     An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track and linear bit density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems. 
     In a tape drive system, the drive moves the magnetic tape over the surface of the tape head at high speed. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial and so goals in these systems are to have the recording gaps of the transducers, which are the source of the magnetic recording flux in near contact with the tape to effect writing sharp transitions, and to have the read elements in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read elements. 
     Brushless direct current (DC) motors are used in tape drives to induce motion of the magnetic tape over the tape head, as brushless DC motors enable high speed tape motion in a compact form factor. Moreover, brushless DC motors have desirably long lifetimes, as they do not include brush contacts which eventually wear out with use over time. Internally, brushless DC motors generally include a stationary stator that has legs which are wrapped with coil windings. The legs provide a magnetic path that couples with a sub-assembly, and is thereby able to induce a relative rotational movement between the sub-assembly and the stator. Specifically, the coupling of the magnetic paths to the magnetic field generated by the coils wrapped around the stator legs create a torque which thereby includes the rotational motion which may selectively be used to transport tape from supply reel to take-up reel, and/or vice versa. However, while a net resulting torque is being generated by the magnetic coupling effect in the motor, there are also subtle oscillations in the torque. These oscillations cause the torque waveform output by brushless DC motors to have a cyclical nature. 
     Moreover, because the stator is magnetically coupled to the rotor sub-assembly, the forces acted on the rotor sub-assembly by cycling the electrical current through the coils of the stator, are also acted on the stator legs themselves, and hence the stator support feature as well. Furthermore, these reaction forces are transmitted throughout the main support plate also, as the stator is rigidly coupled to the main support plate in conventional brushless DC motors. Many conventional brushless DC motors also implement a tape drive deck plate that supports both the motor itself as well as the head actuator assembly used to perform read/write operations. 
     Accordingly, although undesirable variations in the torque waveform are produced at the stator level, these disturbances are transmitted up to the magnetic tape head itself. The spacing between the magnetic tape head and a magnetic medium positioned thereover becomes unstable as a result of these disturbances as well, thereby negatively effecting the position error signal (PES) during operation. Again, as tape drive capacities trend toward higher capacities, the detrimental effects of these instabilities is only compounded. 
     SUMMARY 
     An apparatus, according to one embodiment, includes: a support plate, a stator, a rotor sub-assembly, and at least one isolation mount coupled between the support plate and the stator. The isolation mount is for reducing transfer of vibration from the stator to the support plate. Moreover, the stator is coplanar with the support plate. The rotor sub-assembly includes a magnet, and a hub rotatably fixed relative to the magnet. The rotor sub-assembly is also configured to rotate relative to the support plate and the stator. 
     As mentioned above, the isolation mounts desirably act to reduce vibration caused by the stator. Accordingly, the insulator serves as a vibration insulator which dampens disturbances caused by the stator and/or the sub-assembly from effecting the support plate and/or other components which may be coupled to the support plate, e.g., such as a magnetic head of the tape drive in which the motor may be located. 
     It follows that the support plate and the stator are desirably not in direct contact with each other. Rather, an inner circumference of the support plate is separated from an outer circumference of the stator by a gap, and the at least one isolation mount is positioned in the gap. Thus, the at least one isolation mount couples the stator to the support plate, thereby insulating the support plate from vibrational disturbances. 
     In order to achieve the desirable vibrational insulative properties mentioned above, the at least one isolation mount includes a viscoelastic material. Moreover, the viscoelastic material may be a material characterized by converting kinetic energy into heat. 
     A brushless DC motor, according to another embodiment, includes: a support plate, a stator, a rotor sub-assembly, and at least one isolation mount coupled between the support plate and the stator. The isolation mount is for reducing transfer of vibration from the stator to the support plate. Furthermore, the rotor sub-assembly is configured to rotate relative to the support plate and the stator. 
     Again, the isolation mounts desirably act to reduce vibration caused by the stator. Accordingly, the insulator serves as a vibration insulator which dampens disturbances caused by the stator and/or the sub-assembly from effecting the support plate and/or other components which may be coupled to the support plate, e.g., such as a magnetic head of the tape drive in which the motor may be located. 
     It follows that the support plate and the stator are desirably not in direct contact with each other. Rather, an inner circumference of the support plate is separated from an outer circumference of the stator by a gap, and the at least one isolation mount is positioned in the gap. Thus, the at least one isolation mount couples the stator to the support plate, thereby insulating the support plate from vibrational disturbances. 
     In order to achieve the desirable vibrational insulative properties mentioned above, the at least one isolation mount includes a viscoelastic material. Moreover, the viscoelastic material may be a material characterized by converting kinetic energy into heat. 
     Any of these embodiments may be implemented in a magnetic data storage system such as a tape drive system, which may include a magnetic head, a drive mechanism for passing a magnetic medium (e.g., recording tape) over the magnetic head, and a controller electrically coupled to the magnetic head. 
     Other aspects and embodiments of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic diagram of a simplified tape drive system according to one embodiment. 
         FIG. 1B  is a schematic diagram of a tape cartridge according to one embodiment. 
         FIG. 2A  illustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head according to one embodiment. 
         FIG. 2B  is a tape bearing surface view taken from Line  2 B of  FIG. 2A . 
         FIG. 2C  is a detailed view taken from Circle  2 C of  FIG. 2B . 
         FIG. 2D  is a detailed view of a partial tape bearing surface of a pair of modules. 
         FIG. 3  is a partial tape bearing surface view of a magnetic head having a write-read-write configuration. 
         FIG. 4  is a partial tape bearing surface view of a magnetic head having a read-write-read configuration. 
         FIG. 5  is a side view of a magnetic tape head with three modules according to one embodiment where the modules all generally lie along about parallel planes. 
         FIG. 6  is a side view of a magnetic tape head with three modules in a tangent (angled) configuration. 
         FIG. 7  is a side view of a magnetic tape head with three modules in an overwrap configuration. 
         FIGS. 8A-8C  are schematics depicting the principles of tape tenting. 
         FIG. 9  is a representational diagram of files and indexes stored on a magnetic tape according to one embodiment. 
         FIG. 10A  is a partial perspective view of a brushless DC motor according to one embodiment. 
         FIG. 10B  is a partial cross-sectional view of the brushless DC motor in  FIG. 10A  taken along line  10 B- 10 B. 
         FIG. 11A  is a partial perspective view of a brushless DC motor according to one embodiment. 
         FIG. 11B  is a partial cross-sectional view of the brushless DC motor in  FIG. 11A  taken along line  11 B- 11 B. 
         FIG. 11C  is a partial perspective view of a brushless DC motor according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is made for the purpose of illustrating the general principles of the present invention and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations. 
     Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc. 
     It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless otherwise specified. 
     The following description discloses several preferred embodiments of magnetic storage systems, as well as operation and/or component parts thereof for reducing the effects that a brushless DC motor has on its surrounding environment. Accordingly, some of the embodiments included herein may desirably improve the read and/or write accuracy of a tape drive in which the motor may be implemented, e.g., as will be described in further detail below. 
     In one general embodiment, an apparatus includes: a support plate, a stator, at least one isolation mount coupled between the support plate and the stator for reducing transfer of vibration from the stator to the support plate, and a rotor sub-assembly. Furthermore, the rotor sub-assembly is configured to rotate relative to the support plate and the stator, the rotor sub-assembly including: a magnet, and a hub rotatably fixed relative to the magnet. 
     In another general embodiment, a brushless DC motor includes: a support plate, a stator, at least one isolation mount coupled between the support plate and the stator for reducing transfer of vibration from the stator to the support plate, and a rotor sub-assembly. Furthermore, the rotor sub-assembly is configured to rotate relative to the support plate and the stator, the rotor sub-assembly including: a magnet, and a hub rotatably fixed relative to the magnet. 
       FIG. 1A  illustrates a simplified tape drive  100  of a tape-based data storage system, which may be employed in the context of the present invention. While one specific implementation of a tape drive is shown in  FIG. 1A , it should be noted that the embodiments described herein may be implemented in the context of any type of tape drive system. 
     As shown, a tape supply cartridge  120  and a take-up reel  121  are provided to support a tape  122 . One or more of the reels may form part of a removable cartridge and are not necessarily part of the drive  100 . The tape drive, such as that illustrated in  FIG. 1A , may further include one or more drive motors (e.g., see  FIGS. 10A-11B  below) to drive the tape supply cartridge  120  and the take-up reel  121  to move the tape  122  over a tape head  126  of any type. Such head may include an array of readers, writers, or both. 
     Guides  125  guide the tape  122  across the tape head  126 . Such tape head  126  is in turn coupled to a controller  128  via a cable  130 . The controller  128 , may be or include a processor and/or any logic for controlling any subsystem of the drive  100 . For example, the controller  128  typically controls head functions such as servo following, data writing, data reading, etc. The controller  128  may include at least one servo channel and at least one data channel, each of which include data flow processing logic configured to process and/or store information to be written to and/or read from the tape  122 . The controller  128  may operate under logic known in the art, as well as any logic disclosed herein, and thus may be considered as a processor for any of the descriptions of tape drives included herein, in various embodiments. The controller  128  may be coupled to a memory  136  of any known type, which may store instructions executable by the controller  128 . Moreover, the controller  128  may be configured and/or programmable to perform or control some or all of the methodology presented herein. Thus, the controller  128  may be considered to be configured to perform various operations by way of logic programmed into one or more chips, modules, and/or blocks; software, firmware, and/or other instructions being available to one or more processors; etc., and combinations thereof. 
     The cable  130  may include read/write circuits to transmit data to the head  126  to be recorded on the tape  122  and to receive data read by the head  126  from the tape  122 . An actuator  132  controls position of the head  126  relative to the tape  122 . 
     An interface  134  may also be provided for communication between the tape drive  100  and a host (internal or external) to send and receive the data and for controlling the operation of the tape drive  100  and communicating the status of the tape drive  100  to the host, all as will be understood by those of skill in the art. 
       FIG. 1B  illustrates an exemplary tape cartridge  150  according to one embodiment. Such tape cartridge  150  may be used with a system such as that shown in  FIG. 1A . As shown, the tape cartridge  150  includes a housing  152 , a tape  122  in the housing  152 , and a nonvolatile memory  156  coupled to the housing  152 . In some approaches, the nonvolatile memory  156  may be embedded inside the housing  152 , as shown in  FIG. 1B . In more approaches, the nonvolatile memory  156  may be attached to the inside or outside of the housing  152  without modification of the housing  152 . For example, the nonvolatile memory may be embedded in a self-adhesive label  154 . In one preferred embodiment, the nonvolatile memory  156  may be a Flash memory device, read-only memory (ROM) device, etc., embedded into or coupled to the inside or outside of the tape cartridge  150 . The nonvolatile memory is accessible by the tape drive and the tape operating software (the driver software), and/or another device. 
     By way of example,  FIG. 2A  illustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head  200  which may be implemented in the context of the present invention. As shown, the head includes a pair of bases  202 , each equipped with a module  204 , and fixed at a small angle α with respect to each other. The bases may be “U-beams” that are adhesively coupled together. Each module  204  includes a substrate  204 A and a closure  204 B with a thin film portion, commonly referred to as a “gap” in which the readers and/or writers  206  are formed. In use, a tape  208  is moved over the modules  204  along a media (tape) bearing surface  209  in the manner shown for reading and writing data on the tape  208  using the readers and writers. The wrap angle θ of the tape  208  at edges going onto and exiting the flat media support surfaces  209  are usually between about 0.1 degree and about 3 degrees. 
     The substrates  204 A are typically constructed of a wear resistant material, such as a ceramic. The closures  204 B may be made of the same or similar ceramic as the substrates  204 A. 
     The readers and writers may be arranged in a piggyback or merged configuration. An illustrative piggybacked configuration comprises a (magnetically inductive) writer transducer on top of (or below) a (magnetically shielded) reader transducer (e.g., a magnetoresistive reader, etc.), wherein the poles of the writer and the shields of the reader are generally separated. An illustrative merged configuration comprises one reader shield in the same physical layer as one writer pole (hence, “merged”). The readers and writers may also be arranged in an interleaved configuration. Alternatively, each array of channels may be readers or writers only. Any of these arrays may contain one or more servo track readers for reading servo data on the medium. 
       FIG. 2B  illustrates the tape bearing surface  209  of one of the modules  204  taken from Line  2 B of  FIG. 2A . A representative tape  208  is shown in dashed lines. The module  204  is preferably long enough to be able to support the tape as the head steps between data bands. 
     In this example, the tape  208  includes 4 to 32 data bands, e.g., with 16 data bands and 17 servo tracks  210 , as shown in  FIG. 2B  on a one-half inch wide tape  208 . The data bands are defined between servo tracks  210 . Each data band may include a number of data tracks, for example 1024 data tracks (not shown). During read/write operations, the readers and/or writers  206  are positioned to specific track positions within one of the data bands. Outer readers, sometimes called servo readers, read the servo tracks  210 . The servo signals are in turn used to keep the readers and/or writers  206  aligned with a particular set of tracks during the read/write operations. 
       FIG. 2C  depicts a plurality of readers and/or writers  206  formed in a gap  218  on the module  204  in Circle  2 C of  FIG. 2B . As shown, the array of readers and writers  206  includes, for example, 16 writers  214 , 16 readers  216  and two servo readers  212 , though the number of elements may vary. Illustrative embodiments include 8, 16, 32, 40, and 64 active readers and/or writers  206  per array, and alternatively interleaved designs having odd numbers of reader or writers such as 17, 25, 33, etc. An illustrative embodiment includes 32 readers per array and/or 32 writers per array, where the actual number of transducer elements could be greater, e.g., 33, 34, etc. This allows the tape to travel more slowly, thereby reducing speed-induced tracking and mechanical difficulties and/or execute fewer “wraps” to fill or read the tape. While the readers and writers may be arranged in a piggyback configuration as shown in  FIG. 2C , the readers  216  and writers  214  may also be arranged in an interleaved configuration. Alternatively, each array of readers and/or writers  206  may be readers or writers only, and the arrays may contain one or more servo readers  212 . As noted by considering  FIGS. 2A and 2B-2C  together, each module  204  may include a complementary set of readers and/or writers  206  for such things as bi-directional reading and writing, read-while-write capability, backward compatibility, etc. 
       FIG. 2D  shows a partial tape bearing surface view of complementary modules of a magnetic tape head  200  according to one embodiment. In this embodiment, each module has a plurality of read/write (R/W) pairs in a piggyback configuration formed on a common substrate  204 A and an optional electrically insulative layer  236 . The writers, exemplified by the write transducer  214  and the readers, exemplified by the read transducer  216 , are aligned parallel to an intended direction of travel of a tape medium thereacross to form an R/W pair, exemplified by the R/W pair  222 . Note that the intended direction of tape travel is sometimes referred to herein as the direction of tape travel, and such terms may be used interchangeably. Such direction of tape travel may be inferred from the design of the system, e.g., by examining the guides; observing the actual direction of tape travel relative to the reference point; etc. Moreover, in a system operable for bi-direction reading and/or writing, the direction of tape travel in both directions is typically parallel and thus both directions may be considered equivalent to each other. 
     Several R/W pairs  222  may be present, such as 8, 16, 32 pairs, etc. The R/W pairs  222  as shown are linearly aligned in a direction generally perpendicular to a direction of tape travel thereacross. However, the pairs may also be aligned diagonally, etc. Servo readers  212  are positioned on the outside of the array of R/W pairs, the function of which is well known. 
     Generally, the magnetic tape medium moves in either a forward or backward direction as indicated by arrow  220 . The magnetic tape medium and head assembly  200  operate in a transducing relationship in the manner well-known in the art. The piggybacked magnetoresistive (MR) head assembly  200  includes two thin-film modules  224  and  226  of generally identical construction. 
     Modules  224  and  226  are joined together with a space present between closures  204 B thereof (partially shown) to form a single physical unit to provide read-while-write capability by activating the writer of the leading module and reader of the trailing module aligned with the writer of the leading module parallel to the direction of tape travel relative thereto. When a module  224 ,  226  of a piggyback head  200  is constructed, layers are formed in the gap  218  created above an electrically conductive substrate  204 A (partially shown), e.g., of AlTiC, in generally the following order for the R/W pairs  222 : an insulating layer  236 , a first shield  232  typically of an iron alloy such as NiFe (−), cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor  234  for sensing a data track on a magnetic medium, a second shield  238  typically of a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known as permalloy), first and second writer pole tips  228 ,  230 , and a coil (not shown). The sensor may be of any known type, including those based on MR, GMR, AMR, tunneling magnetoresistance (TMR), etc. 
     The first and second writer poles  228 ,  230  may be fabricated from high magnetic moment materials such as ˜45/55 NiFe. Note that these materials are provided by way of example only, and other materials may be used. Additional layers such as insulation between the shields and/or pole tips and an insulation layer surrounding the sensor may be present. Illustrative materials for the insulation include alumina and other oxides, insulative polymers, etc. 
     The configuration of the tape head  126  according to one embodiment includes multiple modules, preferably three or more. In a write-read-write (W-R-W) head, outer modules for writing flank one or more inner modules for reading. Referring to  FIG. 3 , depicting a W-R-W configuration, the outer modules  252 ,  256  each include one or more arrays of writers  260 . The inner module  254  of  FIG. 3  includes one or more arrays of readers  258  in a similar configuration. Variations of a multi-module head include a R-W-R head ( FIG. 4 ), a R-R-W head, a W-W-R head, etc. In yet other variations, one or more of the modules may have read/write pairs of transducers. Moreover, more than three modules may be present. In further approaches, two outer modules may flank two or more inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. For simplicity, a W-R-W head is used primarily herein to exemplify embodiments of the present invention. One skilled in the art apprised with the teachings herein will appreciate how permutations of the present invention would apply to configurations other than a W-R-W configuration. 
       FIG. 5  illustrates a magnetic head  126  according to one embodiment of the present invention that includes first, second and third modules  302 ,  304 ,  306  each having a tape bearing surface  308 ,  310 ,  312  respectively, which may be flat, contoured, etc. Note that while the term “tape bearing surface” appears to imply that the surface facing the tape  315  is in physical contact with the tape bearing surface, this is not necessarily the case. Rather, only a portion of the tape may be in contact with the tape bearing surface, constantly or intermittently, with other portions of the tape riding (or “flying”) above the tape bearing surface on a layer of air, sometimes referred to as an “air bearing”. The first module  302  will be referred to as the “leading” module as it is the first module encountered by the tape in a three module design for tape moving in the indicated direction. The third module  306  will be referred to as the “trailing” module. The trailing module follows the middle module and is the last module seen by the tape in a three module design. The leading and trailing modules  302 ,  306  are referred to collectively as outer modules. Also note that the outer modules  302 ,  306  will alternate as leading modules, depending on the direction of travel of the tape  315 . 
     In one embodiment, the tape bearing surfaces  308 ,  310 ,  312  of the first, second and third modules  302 ,  304 ,  306  lie on about parallel planes (which is meant to include parallel and nearly parallel planes, e.g., between parallel and tangential as in  FIG. 6 ), and the tape bearing surface  310  of the second module  304  is above the tape bearing surfaces  308 ,  312  of the first and third modules  302 ,  306 . As described below, this has the effect of creating the desired wrap angle α 2  of the tape relative to the tape bearing surface  310  of the second module  304 . 
     Where the tape bearing surfaces  308 ,  310 ,  312  lie along parallel or nearly parallel yet offset planes, intuitively, the tape should peel off of the tape bearing surface  308  of the leading module  302 . However, the vacuum created by the skiving edge  318  of the leading module  302  has been found by experimentation to be sufficient to keep the tape adhered to the tape bearing surface  308  of the leading module  302 . The trailing edge  320  of the leading module  302  (the end from which the tape leaves the leading module  302 ) is the approximate reference point which defines the wrap angle α 2  over the tape bearing surface  310  of the second module  304 . The tape stays in close proximity to the tape bearing surface until close to the trailing edge  320  of the leading module  302 . Accordingly, read and/or write elements  322  may be located near the trailing edges of the outer modules  302 ,  306 . These embodiments are particularly adapted for write-read-write applications. 
     A benefit of this and other embodiments described herein is that, because the outer modules  302 ,  306  are fixed at a determined offset from the second module  304 , the inner wrap angle α 2  is fixed when the modules  302 ,  304 ,  306  are coupled together or are otherwise fixed into a head. The inner wrap angle α 2  is approximately tan −1 (δ/W) where δ is the height difference between the planes of the tape bearing surfaces  308 ,  310  and W is the width between the opposing ends of the tape bearing surfaces  308 ,  310 . An illustrative inner wrap angle α 2  is in a range of about 0.3° to about 1.1°, though can be any angle required by the design. 
     Beneficially, the inner wrap angle α 2  on the side of the module  304  receiving the tape (leading edge) will be larger than the inner wrap angle α 3  on the trailing edge, as the tape  315  rides above the trailing module  306 . This difference is generally beneficial as a smaller α 3  tends to oppose what has heretofore been a steeper exiting effective wrap angle. 
     Note that the tape bearing surfaces  308 ,  312  of the outer modules  302 ,  306  are positioned to achieve a negative wrap angle at the trailing edge  320  of the leading module  302 . This is generally beneficial in helping to reduce friction due to contact with the trailing edge  320 , provided that proper consideration is given to the location of the crowbar region that forms in the tape where it peels off the head. This negative wrap angle also reduces flutter and scrubbing damage to the elements on the leading module  302 . Further, at the trailing module  306 , the tape  315  flies over the tape bearing surface  312  so there is virtually no wear on the elements when tape is moving in this direction. Particularly, the tape  315  entrains air and so will not significantly ride on the tape bearing surface  312  of the third module  306  (some contact may occur). This is permissible, because the leading module  302  is writing while the trailing module  306  is idle. 
     Writing and reading functions are performed by different modules at any given time. In one embodiment, the second module  304  includes a plurality of data and optional servo readers  331  and no writers. The first and third modules  302 ,  306  include a plurality of writers  322  and no data readers, with the exception that the outer modules  302 ,  306  may include optional servo readers. The servo readers may be used to position the head during reading and/or writing operations. The servo reader(s) on each module are typically located towards the end of the array of readers or writers. 
     By having only readers or side by side writers and servo readers in the gap between the substrate and closure, the gap length can be substantially reduced. Typical heads have piggybacked readers and writers, where the writer is formed above each reader. A typical gap is 20-35 microns. However, irregularities on the tape may tend to droop into the gap and create gap erosion. Thus, the smaller the gap is the better. The smaller gap enabled herein exhibits fewer wear related problems. 
     In some embodiments, the second module  304  has a closure, while the first and third modules  302 ,  306  do not have a closure. Where there is no closure, preferably a hard coating is added to the module. One preferred coating is diamond-like carbon (DLC). 
     In the embodiment shown in  FIG. 5 , the first, second, and third modules  302 ,  304 ,  306  each have a closure  332 ,  334 ,  336 , which extends the tape bearing surface of the associated module, thereby effectively positioning the read/write elements away from the edge of the tape bearing surface. The closure  332  on the second module  304  can be a ceramic closure of a type typically found on tape heads. The closures  334 ,  336  of the first and third modules  302 ,  306 , however, may be shorter than the closure  332  of the second module  304  as measured parallel to a direction of tape travel over the respective module. This enables positioning the modules closer together. One way to produce shorter closures  334 ,  336  is to lap the standard ceramic closures of the second module  304  an additional amount. Another way is to plate or deposit thin film closures above the elements during thin film processing. For example, a thin film closure of a hard material such as Sendust or nickel-iron alloy (e.g., 45/55) can be formed on the module. 
     With reduced-thickness ceramic or thin film closures  334 ,  336  or no closures on the outer modules  302 ,  306 , the write-to-read gap spacing can be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% less than commonly-used linear tape open (LTO) tape head spacing. The open space between the modules  302 ,  304 ,  306  can still be set to approximately 0.5 to 0.6 mm, which in some embodiments is ideal for stabilizing tape motion over the second module  304 . 
     Depending on tape tension and stiffness, it may be desirable to angle the tape bearing surfaces of the outer modules relative to the tape bearing surface of the second module.  FIG. 6  illustrates an embodiment where the modules  302 ,  304 ,  306  are in a tangent or nearly tangent (angled) configuration. Particularly, the tape bearing surfaces of the outer modules  302 ,  306  are about parallel to the tape at the desired wrap angle α 2  of the second module  304 . In other words, the planes of the tape bearing surfaces  308 ,  312  of the outer modules  302 ,  306  are oriented at about the desired wrap angle α 2  of the tape  315  relative to the second module  304 . The tape will also pop off of the trailing module  306  in this embodiment, thereby reducing wear on the elements in the trailing module  306 . These embodiments are particularly useful for write-read-write applications. Additional aspects of these embodiments are similar to those given above. 
     Typically, the tape wrap angles may be set about midway between the embodiments shown in  FIGS. 5 and 6 . 
       FIG. 7  illustrates an embodiment where the modules  302 ,  304 ,  306  are in an overwrap configuration. Particularly, the tape bearing surfaces  308 ,  312  of the outer modules  302 ,  306  are angled slightly more than the tape  315  when set at the desired wrap angle α 2  relative to the second module  304 . In this embodiment, the tape does not pop off of the trailing module, allowing it to be used for writing or reading. Accordingly, the leading and middle modules can both perform reading and/or writing functions while the trailing module can read any just-written data. Thus, these embodiments are preferred for write-read-write, read-write-read, and write-write-read applications. In the latter embodiments, closures should be wider than the tape canopies for ensuring read capability. The wider closures may require a wider gap-to-gap separation. Therefore, a preferred embodiment has a write-read-write configuration, which may use shortened closures that thus allow closer gap-to-gap separation. 
     Additional aspects of the embodiments shown in  FIGS. 6 and 7  are similar to those given above. 
     A 32 channel version of a multi-module head  126  may use cables  350  having leads on the same or smaller pitch as current 16 channel piggyback LTO modules, or alternatively the connections on the module may be organ-keyboarded for a 50% reduction in cable span. Over-under, writing pair unshielded cables may be used for the writers, which may have integrated servo readers. 
     The outer wrap angles α 1  may be set in the drive, such as by guides of any type known in the art, such as adjustable rollers, slides, etc. or alternatively by outriggers, which are integral to the head. For example, rollers having an offset axis may be used to set the wrap angles. The offset axis creates an orbital arc of rotation, allowing precise alignment of the wrap angle α 1 . 
     To assemble any of the embodiments described above, conventional u-beam assembly can be used. Accordingly, the mass of the resultant head may be maintained or even reduced relative to heads of previous generations. In other approaches, the modules may be constructed as a unitary body. Those skilled in the art, armed with the present teachings, will appreciate that other known methods of manufacturing such heads may be adapted for use in constructing such heads. Moreover, unless otherwise specified, processes and materials of types known in the art may be adapted for use in various embodiments in conformance with the teachings herein, as would become apparent to one skilled in the art upon reading the present disclosure. 
     As a tape is run over a module, it is preferred that the tape passes sufficiently close to magnetic transducers on the module such that reading and/or writing is efficiently performed, e.g., with a low error rate. According to some approaches, tape tenting may be used to ensure the tape passes sufficiently close to the portion of the module having the magnetic transducers. To better understand this process,  FIGS. 8A-8C  illustrate the principles of tape tenting.  FIG. 8A  shows a module  800  having an upper tape bearing surface  802  extending between opposite edges  804 ,  806 . A stationary tape  808  is shown wrapping around the edges  804 ,  806 . As shown, the bending stiffness of the tape  808  lifts the tape off of the tape bearing surface  802 . Tape tension tends to flatten the tape profile, as shown in  FIG. 8A . Where tape tension is minimal, the curvature of the tape is more parabolic than shown. 
       FIG. 8B  depicts the tape  808  in motion. The leading edge, i.e., the first edge the tape encounters when moving, may serve to skive air from the tape, thereby creating a subambient air pressure between the tape  808  and the tape bearing surface  802 . In  FIG. 8B , the leading edge is the left edge and the right edge is the trailing edge when the tape is moving left to right. As a result, atmospheric pressure above the tape urges the tape toward the tape bearing surface  802 , thereby creating tape tenting proximate each of the edges. The tape bending stiffness resists the effect of the atmospheric pressure, thereby causing the tape tenting proximate both the leading and trailing edges. Modeling predicts that the two tents are very similar in shape. 
       FIG. 8C  depicts how the subambient pressure urges the tape  808  toward the tape bearing surface  802  even when a trailing guide  810  is positioned above the plane of the tape bearing surface. 
     It follows that tape tenting may be used to direct the path of a tape as it passes over a module. As previously mentioned, tape tenting may be used to ensure the tape passes sufficiently close to the portion of the module having the magnetic transducers, preferably such that reading and/or writing is efficiently performed, e.g., with a low error rate. 
     Magnetic tapes may be stored in tape cartridges that are, in turn, stored at storage slots or the like inside a data storage library. The tape cartridges may be stored in the library such that they are accessible for physical retrieval. In addition to magnetic tapes and tape cartridges, data storage libraries may include data storage drives that store data to, and/or retrieve data from, the magnetic tapes. Moreover, tape libraries and the components included therein may implement a file system which enables access to tape and data stored on the tape. 
     File systems may be used to control how data is stored in, and retrieved from, memory. Thus, a file system may include the processes and data structures that an operating system uses to keep track of files in memory, e.g., the way the files are organized in memory. Linear Tape File System (LTFS) is an exemplary format of a file system that may be implemented in a given library in order to enables access to compliant tapes. It should be appreciated that various embodiments herein can be implemented with a wide range of file system formats, including for example IBM Spectrum Archive Library Edition (LTFS LE). However, to provide a context, and solely to assist the reader, some of the embodiments below may be described with reference to LTFS which is a type of file system format. This has been done by way of example only, and should not be deemed limiting on the invention defined in the claims. 
     A tape cartridge may be “loaded” by inserting the cartridge into the tape drive, and the tape cartridge may be “unloaded” by removing the tape cartridge from the tape drive. Once loaded in a tape drive, the tape in the cartridge may be “threaded” through the drive by physically pulling the tape (the magnetic recording portion) from the tape cartridge, and passing it above a magnetic head of a tape drive. Furthermore, the tape may be attached on a take-up reel (e.g., see  121  of  FIG. 1A  above) to move the tape over the magnetic head. 
     Once threaded in the tape drive, the tape in the cartridge may be “mounted” by reading metadata on a tape and bringing the tape into a state where the LTFS is able to use the tape as a constituent component of a file system. Moreover, in order to “unmount” a tape, metadata is preferably first written on the tape (e.g., as an index), after which the tape may be removed from the state where the LTFS is allowed to use the tape as a constituent component of a file system. Finally, to “unthread” the tape, the tape is unattached from the take-up reel and is physically placed back into the inside of a tape cartridge again. The cartridge may remain loaded in the tape drive even after the tape has been unthreaded, e.g., waiting for another read and/or write request. However, in other instances, the tape cartridge may be unloaded from the tape drive upon the tape being unthreaded, e.g., as described above. 
     Magnetic tape is a sequential access medium. Thus, new data is written to the tape by appending the data at the end of previously written data. It follows that when data is recorded in a tape having only one partition, metadata (e.g., allocation information) is continuously appended to an end of the previously written data as it frequently updates and is accordingly rewritten to tape. As a result, the rearmost information is read when a tape is first mounted in order to access the most recent copy of the metadata corresponding to the tape. However, this introduces a considerable amount of delay in the process of mounting a given tape. 
     To overcome this delay caused by single partition tape mediums, the LTFS format includes a tape that is divided into two partitions, which include an index partition and a data partition. The index partition may be configured to record metadata (meta information), e.g., such as file allocation information (Index), while the data partition may be configured to record the body of the data, e.g., the data itself. 
     Looking to  FIG. 9 , a magnetic tape  900  having an index partition  902  and a data partition  904  is illustrated according to one embodiment. As shown, data files and indexes are stored on the tape. The LTFS format allows for index information to be recorded in the index partition  902  at the beginning of tape  906 , as would be appreciated by one skilled in the art upon reading the present description. 
     As index information is updated, it preferably overwrites the previous version of the index information, thereby allowing the currently updated index information to be accessible at the beginning of tape in the index partition. According to the specific example illustrated in  FIG. 9 , a most recent version of metadata Index  3  is recorded in the index partition  902  at the beginning of the tape  906 . Conversely, all three version of metadata Index  1 , Index  2 , Index  3  as well as data File A, File B, File C, File D are recorded in the data partition  904  of the tape. Although Index  1  and Index  2  are old (e.g., outdated) indexes, because information is written to tape by appending it to the end of the previously written data as described above, these old indexes Index  1 , Index  2  remain stored on the tape  900  in the data partition  904  without being overwritten. 
     The metadata may be updated in the index partition  902  and/or the data partition  904  differently depending on the desired embodiment. According to some embodiments, the metadata of the index partition  902  may be updated in response to the tape being unmounted, e.g., such that the index may be read from the index partition when that tape is mounted again. The metadata may also be written in the data partition  902  so the tape may be mounted using the metadata recorded in the data partition  902 , e.g., as a backup option. 
     According to one example, which is no way intended to limit the invention, LTFS LE may be used to provide the functionality of writing an index in the data partition when a user explicitly instructs the system to do so, or at a time designated by a predetermined period which may be set by the user, e.g., such that data loss in the event of sudden power stoppage can be mitigated. 
     As previously mentioned, brushless DC motors are used in many tape drives to induce motion of the magnetic tape over the tape head, as brushless DC motors enable high speed tape motion in a compact form factor. Moreover, brushless DC motors have desirably long lifetimes, as they do not include brush contacts which eventually wear out with use over time. 
     Internally, brushless DC motors may include a stator which has legs that are wrapped with coil windings. Although the stator itself is stationary, electrical currents may be selectively passed through the coil windings. As a result, the legs of the stator may provide a magnetic path that couples with a rotating sub-assembly having a multi poled magnet. The coupling of the magnetic paths to the magnetic field generated by the coils wrapped around the stator legs create the desired torque, and hence induces relative rotational movement between the sub-assembly and the stator. The rotational motion is used to transport tape from one reel to another reel (e.g., supply reel to take-up reel, and/or vice versa). The number of poles on the magnet, as well as the number of stator legs, and overall size of the components may be varied according to the desired performance of the device in which the motor is implemented. 
     While a net resulting torque is being generated by the magnetic coupling effect in the motor, there are also subtle oscillations in the torque. These oscillations cause the torque waveform output by brushless DC motors to have a cyclical nature. Moreover, because the stator is magnetically coupled to the rotor sub-assembly, the forces acted on the rotor sub-assembly by cycling the electrical current through the coils of the stator, also have an effect on the stator legs themselves. 
     These effects are also realized by any features or components which may be directly coupled to the stator. In conventional brushless DC motors, a support plate of the motor is directly and rigidly coupled to the stator, and therefore these reaction forces are transmitted throughout the main support plate as well. Many conventional products also implement a tape drive deck plate that supports both the motor itself as well as the head actuator assembly used to perform read/write operations. Accordingly, although variations in the torque waveform produce subtle oscillations at the stator level, these disturbances are transmitted all the way up to the magnetic tape head itself in conventional products. The spacing between the magnetic tape head and a magnetic medium positioned adjacent thereto becomes unstable as a result of these disturbances as well, thereby negatively effecting the position error signal (PES) during operation. Again, as tape drive capacities continually increase, the detrimental effects of these instabilities experienced in conventional products are only compounded, thereby further reducing performance. 
     In sharp contrast to these shortcomings experienced by conventional products, various ones of the approaches described herein achieve motor configurations which are able to dampen the effects that the torque oscillations have on a remainder of the environment in which the motor is located. For example, by confining the torque oscillations such that they are only detected in the region of the motor in which the stator is positioned, some of the embodiments described herein are able to desirably reduce the effect that the motor has on surrounding components. In approaches where the motor is included in a tape drive environment, the improvements achieved by the approaches included herein are able to improve the efficiency and accuracy by which a magnetic head of the tape drive is able to read from, write to, locate on, etc. a magnetic tape loaded in the tape drive, e.g., as will be described in further detail below. Accordingly, the various approaches included herein may be able to significantly improve performance of tape drives and storage libraries in which they may be positioned. 
     Looking to  FIGS. 10A-10B , an externally supported brushless DC motor  1000  is illustrated in accordance with one embodiment. As an option, the present brushless DC motor  1000  may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS. For example, the brushless DC motor  1000  may be implemented in a tape drive, e.g., as seen in  FIG. 1A . However, such brushless DC motor  1000  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the brushless DC motor  1000  presented herein may be used in any desired environment. Thus  FIGS. 10A-10B  (and the other FIGS.) may be deemed to include any possible permutation. 
     Referring specifically to the partial perspective view in  FIG. 10A , the brushless DC motor  1000  is shown as including a main support plate  1002  which surrounds a stator  1004 . As shown, the stator  1004  in turn surrounds a rotor sub-assembly  1006 , which includes a magnet  1008  and a hub  1010  portion. Although not shown in  FIG. 10A , the main support plate  1002  is preferably coupled to a stationary component of a surrounding environment, e.g., such as an exterior housing of the motor, a frame of a tape drive in which the motor is positioned, etc., thereby making the main support plate  1002  non-rotatable. According to one example, the main support plate  1002  may be a deck casting which holds the motor(s) for tape transport in a tape drive system. Thus, the main support plate  1002  may be considered mechanical ground as would be appreciated by one skilled in the art after reading the present description. 
     The stator  1004  includes a plurality of legs  1012  which extend towards a center of the stator  1004 . Moreover, each of the legs  1012  are preferably wrapped with one or more series of coils (not shown) which are configured to pass a sequence of electrical currents therethrough. Accordingly, each of the one or more series of coils may be coupled to a controllable current supply which is capable of providing a current having a sufficient amplitude and in both positive and negative (e.g., forward and backward) directions along length of the wires which form the respective coils. 
     As mentioned above, passing a current through the coil windings which wrap the legs  1012  of the stator  1004  effectively creates a magnetic field. Thus, the stator  1004  may be used to provide a magnetic path that couples with the magnet  1008  of the sub-assembly  1006 . The magnet  1008  also preferably includes multiple poles which produce multiple magnetic paths that couple to the magnetic field created by the coils of the stator  1004 . This coupling of the magnetic paths to the generated magnetic field creates a resulting torque which acts on the sub-assembly  1006 . 
     As described above, the rotor sub-assembly  1006  is preferably able to rotate, e.g., to unwind/wind a magnetic tape from/onto a supply reel. Thus, the torque acting on the sub-assembly  1006  induces a rotational movement of the sub-assembly  1006 , e.g., at least with respect to the main support plate  1002  and stator  1004  which are preferably nonrotatable. It follows that the rotor sub-assembly  1006  is preferably configured to rotate relative to the main support plate  1002  and the stator  1004 . Accordingly, the magnet  1008  and hub  1010  are also shown as having a general circular shape to facilitate the rotational motion of the sub-assembly  1006 . Moreover, the hub  1010  is preferably rotatably fixed relative to the magnet  1008  such that both the magnet  1008  and the hub  1010  rotate with each other in unison, e.g., as a single unit. Accordingly, the hub  1010  preferably includes a magnetic material which is able to provide a flux path for the attached magnet  1008 , thereby bonding the hub and magnet  1008  together. However, in other approaches the hub  1010  and magnet  1008  may be bonded together using adhesives, fasteners, clamps, etc. 
     It should be noted that the number of poles on the magnet  1008 , the number and/or size of the legs  1012  in the stator  1004 , the number of coil wraps made around each of the legs  1012 , etc., may be varied from the particular embodiments illustrated and/or described herein in order to adjust the performance characteristics of a resulting motor, e.g., as would be appreciated by one skilled in the art after reading the present description. 
     Referring still to  FIG. 10A , although various ones of the components (features) included in the motor  1000  may be in direct contact with each other (e.g., such as the magnet  1008  and the hub  1010 ), it should be noted that the stator  1004  and the main support plate  1002  are not directly coupled to each other. Rather, at least one isolation mount  1016  couples the stator  1004  to the main support plate  1002 . The at least one isolation mount  1016  preferably includes a viscoelastic material (e.g., such as rubber) which is characterized by converting kinetic energy into heat. Thus, the at least one isolation mount  1016  may act as a vibration insulator which dampens any disturbances caused by the stator  1004  from effecting the main support plate  1002  and/or other components which may be coupled to the main support plate  1002 , e.g., as will be described in further detail below. However, depending on a number of isolation mounts  1016  and/or a configuration of the one or more isolation mounts  1016 , portions of the stator  1004  and support plate  1002  may not have an isolation mount positioned therebetween. However, as described above, it is preferred that the stator  1004  and the main support plate  1002  are not directly coupled to each other. Thus, in some approaches a gap exists between the stator  1004  and the support plate  1002  such that the stator  1004  and support plate  1002  refrain from coming into direct contact with each other. In further approaches, the isolation mount  1016  may be coupled to the outer circumference of the stator  1004  and/or the inner circumference of the main support plate  1002  using adhesives, fasteners, retention by friction, slot and grooves, etc., depending on the desired embodiment. 
     Looking to  FIG. 10A , the motor  1000  includes four separate isolation mounts  1016  positioned between the stator  1004  and support plate  1002 . Accordingly, the regions between each of the isolation mounts  1016  include a gap  1018  between an outer circumference of the stator  1004  and the inner circumference of the main support plate  1002 . The width of the gap between the stator  1004  and support plate  1002  is effectively defined by the dimensions of the isolation mounts  1016 , and therefore may have a same thickness as the isolation mounts  1016  measured in the same direction or along the same plane. However, in some approaches, the stator  1004  and/or the main support plate  1002  may have notches (e.g., indents) which cause at least a portion of the isolation mounts  1016  to be recessed into the body of the stator  1004  and/or the main support plate  1002  respectively. These notches may add stability and ensure that the isolation mounts  1016  do not shift during use of the motor  1000 , but are in no way required. However, it should again be mentioned that the stator  1004  and the main support plate  1002  are not directly coupled to each other regardless of the dimensions of the at least one isolation mount  1016 . 
     As mentioned above, the isolation mounts  1016  act as a vibration insulator which dampen any disturbances caused by the stator  1004  and/or the sub-assembly  1006  from effecting the main support plate  1002  and/or other components which may be coupled to the main support plate  1002 , e.g., such as a magnetic head of the tape drive in which the motor  1000  may be located. Thus, the isolation mounts  1016  are preferably configured to reduce the transfer of vibration from the stator  1004  to the support plate  1002 . In addition to separating the stator  1004  and support plate  1002  from being in direct contact with each other, the isolation mounts  1016  preferably include one or more different materials which are able to significantly dampen (reduce) vibrational disturbances from transferring between the stator  1004  and support plate  1002 . 
     According to one approach, the one or more isolation mounts  1016  may achieve this dampening by being constructed of a material characterized by converting kinetic energy into heat, e.g., such as viscoelastic materials. Thus, vibrational disturbances caused by the stator  1004  may be converted into heat and/or other energy byproducts rather than being translated into the main support plate  1002 . This transfer of kinetic energy into heat may be achieved by the isolation mounts  1016  by rotating, compressing, expanding, etc. slightly (e.g., on a microscopic scale), due to the reaction forces exerted on it by the magnetic coupling phenomena occurring during use of the motor  1000 . The isolation mounts  1016  may absorb microscopic counter rotation motion and dampen the disturbance oscillations experienced when the motor  1000  is in use, even in a rigid mount configuration. It should be noted that the configuration shown in  FIGS. 10A-10B  is just one of many possible configurations. Thus, the overall stiffness of the isolation mounts  1016  may be adjusted depending on the desired approach, e.g., based on the amount of vibration, the amplitude of the oscillations produced by the stator  1004 , environment settings, user preference, etc. The precise configuration (e.g., material composition) and/or number of isolation mounts implemented in a given approach, may be selected in an attempt to best match the desired approach. 
     An illustrative list of viscoelastic materials which may be implemented in the isolation mounts  1016  includes, but is in no way limited to, various rubbers; 3M-4991 VHB pressure-sensitive, closed-cell acrylic foam adhesive available from 3M having a sales address at 3M Center, St. Paul, Minn. 55144; 3M-4945 VHB pressure-sensitive, closed-cell acrylic foam adhesive available from 3M having the same sales address; Rogers Corporation PORON® foams available from Rogers Corporation having a sales address at Rm, 1101. Bldg. A. Oriental Media Center, NO 4. Guanghua Rd, Chaoyang District, Beijing 100026, China; Roush RA205 damping foam available from Roush having a sales address at 12011 Market St., Livonia, Mich. 48150; EAR Specialty composites C1002 Isodamping thermoplastic materials available from EAR having a sales address at 7911 Zionsville Road Indianapolis, Ind. 46268; etc., or any other viscoelastic material which would be apparent to one skilled in the art after reading the present description. For instance, in some approaches, one or more of the isolation mounts  1016  may be custom molded from any one or more of the C8012, C1002, C1100, C8002, etc., series materials made by EAR. Further still, in some approaches one or more of the isolation mounts  1016  may include a laminate of layers of viscoelastic materials, each of which may be of the same type of viscoelastic material or may vary. 
     Various approaches described herein are able to desirably reduce or eliminate PES of tape drives by implementing isolation mounts as described herein. The isolation mounts, which preferably include one or more viscoelastic materials, may form a bridge between components of the tape drive which are otherwise separated by a gap. As a result, some of the approaches described herein are desirably able to achieve improved track following operations in comparison to conventional products. Again, the overall stiffness of the isolation mounts  1016  may be adjusted depending on the desired approach, e.g., based on the amount of vibration, the amplitude of the oscillations produced by the stator  1004 , environment settings, user preference, etc. 
     Referring still to  FIG. 10A , although the motor  1000  includes four different isolation mounts  1016 , the number, size, composition, etc. of the isolation mounts  1016  may vary depending on the desired approach. According to one example, which is in no way intended to limit the invention, the motor  1000  may include a single isolation mount which extends along the interface between the stator  1004  and support plate  1002  for more than half of an outer circumference of the stator  1004  and more than half of an inner circumference of the main support plate  1002 . In another example, which is again in no way intended to limit the invention, motor  1000  may include at least two isolation mounts, each of which extend along more than one third of an outer circumference of the stator  1004  and more than one third of an inner circumference of the main support plate  1002 . In still another example, which again in no way intended to limit the invention, motor  1000  may include three or more isolation mounts which are evenly spaced along the interface between the main support plate  1002  and the stator  1004 . 
     As alluded to above, it is preferred in approaches having two or more isolation mounts  1016  that each of the isolation mounts  1016  are separated evenly along the gap  1018 . In other words, it is preferred that each of the isolation mounts  1016  have about an equal amount of space separating it from each other adjacent isolation mount  1016  along the gap  1018 . Evenly spacing the isolation mounts  1016  allows for the motor to be better balanced and better supported, thereby improving performance and reducing instability. 
     As shown in  FIGS. 10A-10B , each of the isolation mounts  1016  may have a cylindrical profile with end caps. The end caps preferably serve as retaining features which are able to hold the respective isolation mounts  1016  in place between the stator  1004  and the main support plate  1002  such that the isolation mounts  1016  do not slip from their intended (desired) position between the stator  1004  and main support plate  1002 . 
     Looking specifically to the cross-sectional view in  FIG. 10B , although not shown, the sub-assembly  1006  may also be supported by an axle and/or bearings in some approaches. The axle and/or bearings may provide a normal force on the sub-assembly  1006  while also facilitating the rotational movement of the sub-assembly  1006  as would be appreciated by one skilled in the art after reading the present description. Accordingly, the sub-assembly  1006  may effectively be mechanically linked to the main support plate  1002  although not specifically shown in the partial view of the motor  1000  illustrated in  FIGS. 10A-10B . Moreover, the axle may include a center shaft which fits in the central hole  1020  of the hub  1010 . 
     It follows that by externally supporting the stator of a brushless DC motor with one or more isolation mounts, disturbance vibrations caused by the torque waveform output by the stator may be significantly reduced with respect to the remainder of the motor. As a result, the motor has less of an effect on its surrounding environment, thereby greatly improving read and/or write accuracy of a tape drive in which the motor may be implemented. 
     While the motor configurations illustrated in  FIGS. 10A-10B  provide significant improvements to the performance of brushless DC motors in general and/or the environments in which they may be implemented (such as a magnetic tape drive), similar results may be achieved for motors with internally supported stators. 
     Accordingly, looking to  FIGS. 11A-11B , an internally supported brushless DC motor  1100  is illustrated in accordance with one embodiment. As an option, the present brushless DC motor  1100  may be implemented in conjunction with features from any other embodiment listed herein, such as those described with reference to the other FIGS. For example, the brushless DC motor  1100  may be implemented in a tape drive, e.g., as seen in  FIG. 1A . However, such brushless DC motor  1100  and others presented herein may be used in various applications and/or in permutations which may or may not be specifically described in the illustrative embodiments listed herein. Further, the brushless DC motor  1100  presented herein may be used in any desired environment. Thus  FIGS. 11A-11B  (and the other FIGS.) may be deemed to include any possible permutation. 
     Referring specifically to the partial perspective view in  FIG. 11A , the brushless DC motor  1100  is shown as including a main support plate  1102  which surrounds a rotor sub-assembly  1106  and a stator  1104 . As shown, the rotor sub-assembly  1106  in the present embodiment surrounds the stator  1104 , but may function in the same or a similar manner as the rotor sub-assembly of the motor  1000  in  FIGS. 10A-10B  as described above. Accordingly, the sub-assembly  1106  in  FIGS. 11A-11B  includes a magnet  1108  and a hub  1110  portion. Again, although not shown in  FIGS. 11A-11B , the main support plate  1102  is preferably coupled to a stationary component of a surrounding environment, e.g., such as an exterior housing of the motor, a frame of a tape drive in which the motor is positioned, etc., thereby making the main support plate  1102  non-rotatable. According to one example, the main support plate  1002  may be a deck casting which holds the motor(s) for tape transport in a tape drive system. Thus, the main support plate  1102  may be considered mechanical ground as would be appreciated by one skilled in the art after reading the present description. 
     The main support plate  1102  may also be coupled to a first end of a stator support arm  1120  which extends between the main support plate  1102  and the stator  1104 . As previously mentioned, motor  1100  is internally supported in comparison to the externally supported motor  1000  in  FIGS. 10A-10B . However, referring still to  FIGS. 11A-11B , it should be noted that the stator support arm  1120  and the stator  1104  itself are not in direct contact with each other. Rather, an isolation mount  1116  is positioned between a second end of the stator support arm  1120  (opposite the first end of the stator support arm  1120  coupled to the main support plate  1102 ) and the stator  1104 . Thus, the isolation mount  1116  effectively couples the stator support arm  1120  and the stator  1104  together while also attenuating vibrational disturbances caused by the stator  1104  from translating through the stator support arm  1120  to the main support plate  1102  and beyond, e.g., as will be described in further detail below. 
     The stator  1104  includes a plurality of legs  1112  which extend towards a center of the stator  1104 . Moreover, each of the legs  1112  are preferably wrapped with one or more series of coils (not shown) which are configured to pass a sequence of electrical currents therethrough. Accordingly, each of the one or more series of coils may be coupled to a controllable current supply which is capable of providing a current having a sufficient amplitude and in both positive and negative (e.g., forward and backward) directions along length of the wires which form the respective coils. 
     As mentioned above, passing a current through the coil windings which wrap the legs  1112  of the stator  1104  effectively creates a magnetic field. Thus, the stator  1104  may be used to provide a magnetic path that couples with the magnet  1108  of the sub-assembly  1106 . The magnet  1108  also preferably includes multiple poles which produce multiple magnetic paths that couple to the magnetic fields created by the coils of the stator  1104 . This coupling of the magnetic paths to the generated magnetic fields creates a resulting torque which acts on the sub-assembly  1106 . 
     Again, the rotor sub-assembly  1106  is preferably able to rotate, e.g., to unwind/wind a magnetic tape from/onto a supply reel. Thus, the torque acting on the sub-assembly  1106  induces a rotational movement of the sub-assembly  1106 , e.g., at least with respect to the main support plate  1102  and stator  1104  which are preferably nonrotatable. It follows that the rotor sub-assembly  1106  is preferably configured to rotate relative to the main support plate  1102  and the stator  1104 . Accordingly, the magnet  1108  and hub  1110  are also shown as having a general circular shape to facilitate the rotational motion of the sub-assembly  1106 . Moreover, the hub  1110  is preferably rotatably fixed relative to the magnet  1108  such that both the magnet  1108  and the hub  1110  rotate with each other in unison, e.g., as a single unit. Accordingly, the hub  1110  preferably includes a magnetic material which is able to provide a flux path for the attached magnet  1108 , thereby bonding the hub and magnet  1108  together. However, in other approaches the hub  1110  and magnet  1108  may be bonded together using adhesives, fasteners, clamps, etc. Additionally, a gap  1118  (spacing) exists between the hub  1110  and the main support plate  1102  such that the sub-assembly  1106  may rotate freely without rubbing against the rotatably fixed support plate  1102 . 
     One of the differences between motors having internally supported stators compared to externally supported stators is the size of the rotor sub-assembly. Referring momentarily back to  FIG. 10A , because the stator  1004  is supported by (e.g., coupled to) the main support plate  1002  using the isolation mounts  1016 , the rotor sub-assembly  1006  is located at the center of the stator  1004  such that the sub-assembly  1006  may rotate freely without compromising the stability of the stator  1004 . Alternatively, referring now to  FIGS. 11A-11B , an internally supported brushless DC motor  1100  may be supported at or near a center of the stator  1104  by a support arm  1120  which extends from a mechanical ground, such as the main support plate  1102 . Accordingly, the rotor sub-assembly  1106  in an internally supported motor  1100  may be positioned at an exterior of the stator  1104  in order to rotate freely rather than at the center of the stator as seen in externally supported motors. 
     Accordingly, the rotor sub-assembly may have a larger circumference in internally supported brushless DC motors compared to similarly sized externally supported brushless DC motors. A rotor sub-assembly having a larger circumference (and thereby diameter) may translate into a motor which has a greater achievable torque compared to a rotor sub-assembly which has a smaller circumference. Accordingly, internally supported brushless DC motors may be more desirably used in certain situations, while externally supported brushless DC motors may be more desirably used in other situations. 
     Referring back to  FIGS. 11A-11B , it should be noted that the number of poles on the magnet  1108 , the number and/or size of the legs  1112  in the stator  1104 , the number of coil wraps made around each of the legs  1112 , etc., may be varied from the particular embodiments illustrated and/or described herein in order to adjust the performance characteristics of a resulting motor, e.g., as would be appreciated by one skilled in the art after reading the present description. 
     Additionally, although various ones of the components (features) included in the motor  1100  may be in direct contact with each other (e.g., such as the magnet  1108  and the hub  1110 ), the stator  1104  and the stator support arm  1120  are not directly coupled to each other. Rather, at least one isolation mount  1116  couples the stator  1104  to the stator support arm  1120 . The at least one isolation mount  1116  preferably includes a viscoelastic material (e.g., such as rubber) which is characterized by converting kinetic energy into heat. Thus, the at least one isolation mount  1116  may act as a vibration insulator which dampens any disturbances caused by the stator  1104  from effecting the main support plate  1102  and/or other components which may be coupled to the main stator support arm  1120 . However, depending on a number of isolation mounts  1116  and/or a configuration of the at least one isolation mount  1116 , portions of the stator  1104  and stator support arm  1120  may not have an isolation mount (or portion thereof) positioned therebetween. However, it is again preferred that the stator  1104  and stator support arm  1120  are not directly coupled to each other. Thus, in some approaches a gap exists between the stator  1104  and the stator support arm  1120  such that the stator  1104  and stator support arm  1120  refrain from coming into direct contact with each other. 
     Looking specifically to  FIGS. 11A-11B , the motor  1100  includes a single isolation mount  1116  positioned between the stator  1104  and the stator support arm  1120 . In the present approach, the isolation mount  1116  fully encircles the second end of the stator support arm  1120  while similarly extending along the whole inner circumference of the stator  1104 . Additionally, the isolation mount  1116  is shown as being a solid piece of material having an indent in an upper and lower surface thereof. However, in other approaches the motor  1100  may include more than one isolation mount, each of which are separated by about an equal amount (e.g., see isolation mounts  1016  in  FIG. 10A ). For example, the motor  1100  may include at least three isolation mounts which are evenly spaced along an interface between the second end of the stator support arm  1120  and the stator  1104 . Accordingly, the regions between each of the more than one isolation mount  1116  may form a gap between an inner circumference of the stator  1104  and an outer circumference of the stator support arm  1120 . In such approaches, the dimension of the gap between the stator  1104  and stator support arm  1120  may effectively be defined by the dimensions of the more than one isolation mount, and therefore may have one or more same dimensions as those of the isolation mounts measured in the same direction or along a same plane. In other approached, the isolation mount  1116  fully encircles the second end of the stator support arm  1120 , e.g., as seen in  FIGS. 11A-11B , but may further have vias formed therethrough. Referring momentarily to  FIG. 11C , a motor  1150  having an isolation mount  1152  with vias  1154  formed therethrough is illustrated in accordance with an illustrative embodiment which is in no way intended to limit the invention. It follows that the isolation mounts included herein may take any desired shape depending on the approach. Such geometric changes may be made to the isolation mounts described herein to provide a sufficient overall support of the stator, while also providing sufficient damping of disturbances emanating from the stator. 
     However, in some approaches, the stator  1104  and/or the stator support arm  1120  may have notches (e.g., indents) which cause at least a portion of the isolation mount  1116  to be recessed into the body of the stator  1104  and/or the stator support arm  1120  respectively. These notches may add stability and ensure that the isolation mounts  1116  do not shift during use of the motor  1100 , but are in no way required. However, it should again be mentioned that the stator  1104  and the main support plate  1102  are not directly coupled to each other regardless of the dimensions of the at least one isolation mount  1116 . In further approaches, the isolation mount  1116  may be coupled to the inner circumference of the stator  1104  and/or the outer circumference of the stator support arm  1120  using adhesives, fasteners, retention by friction, slot and grooves, etc., depending on the desired embodiment. 
     As mentioned above, the isolation mounts  1116  act as a vibration insulator which dampen any disturbances caused by the stator  1104  and/or the sub-assembly  1106  from effecting the main support plate  1102  and/or other components which may be coupled to the main support plate  1102 , e.g., such as a magnetic head of the tape drive in which the motor  1100  may be located. Thus, the isolation mounts  1116  are preferably configured to reduce the transfer of vibration from the stator  1104  to the stator support arm  1120  and further the support plate  1102 . In addition to separating the stator  1104  and stator support arm  1120  from being in direct contact with each other, the isolation mounts  1116  preferably include one or more different materials which are able to significantly dampen (reduce) vibrational disturbances from transferring between the stator  1104  and stator support arm  1120 . 
     According to one approach, the one or more isolation mounts  1116  may achieve this dampening by being constructed of a material characterized by converting kinetic energy into heat, e.g., such as viscoelastic materials. Thus, vibrational disturbances caused by the stator  1104  may be converted into heat and/or other energy byproducts (e.g., sound) rather than being translated into the stator support arm  1120  and main support plate  1102 . This transfer of kinetic energy into heat may be achieved by the isolation mounts  1116  by rotating, compressing, expanding, etc. slightly (e.g., on a microscopic scale), due to the reaction forces exerted on it by the magnetic coupling phenomena occurring during use of the motor  1100 . The isolation mounts  1116  may absorb microscopic counter rotation motion and dampen the disturbance oscillations experienced when the motor  1100  is in use, even in a rigid mount configuration. It should be noted that the configuration shown in  FIGS. 11A-11B  is just one of many possible configurations. The precise configuration (e.g., material composition) and/or number of isolation mounts implemented in a given approach, may be selected in an attempt to best match the desired approach. Depending on the approach, the isolation mount  1116  may include any one or more of the viscoelastic materials described above with respect to the isolation mounts  1016  of  FIGS. 10A-10B . Moreover, the overall stiffness of the isolation mount(s)  1116  may be adjusted depending on the desired approach, e.g., based on the amount of vibration, the amplitude of the oscillations produced by the stator  1104 , environment settings, user preference, etc. 
     Looking specifically to the cross-sectional view in  FIG. 11B , although not shown, the sub-assembly  1106  may also be supported by an axle and/or bearings in some approaches. The axle and/or bearings may provide a normal force on the sub-assembly  1106  while also facilitating the rotational movement of the sub-assembly  1106  as would be appreciated by one skilled in the art after reading the present description. Accordingly, the sub-assembly  1106  may effectively be mechanically linked to the main support plate  1102 , although not specifically shown in the partial view of the motor  1100  illustrated in  FIGS. 11A-11B . Moreover, the axle may include a center shaft which fits in a recessed portion of the hub  1110 . 
     It follows that by internally supporting the stator of a brushless DC motor with one or more isolation mounts, disturbance vibrations caused by the torque waveform output by the stator may be significantly reduced with respect to the remainder of the motor. As a result, the motor has less of an effect on its surrounding environment, thereby greatly improving read and/or write accuracy of a tape drive in which the motor may be implemented. 
     It should be noted that although various components in the motors described herein are illustrated and/or described as having a generally circular shape, any number of different shaped configurations may be implemented depending on the desired embodiment. For example, an internally supported stator may have a square center recess rather than a circular one as seen in  FIGS. 11A-11B . Accordingly, the isolation mount and/or second end of the stator support arm in  FIGS. 11A-11B  may have a square profile as well. In other approaches, the externally supported stator in  FIGS. 10A-10B  may have a square shaped outer surface, along with a circular inner recess. Thus, an inner surface of the main support plate may have a square profile as well while maintaining one or more isolation mounts positioned between the main support plate and the stator according to any of the approaches described above. 
     Similarly, although the stator support arm  1120  in  FIGS. 11A-11B  extends between the main support plate  1102  and a center of the stator  1104 , in other approaches the stator support arm may extend between the main support plate  1102  and an area of the stator  1104  which is not the center thereof while maintaining the desired functionality of the motor  1100  as a whole, e.g., depending on the overall shape and/or configuration of the stator  1104 . 
     Furthermore, although only a single motor is shown in each of  FIGS. 10A-10B and 11A-11B  respectively, more than one motor may be implemented in a given approach. For instance, a tape drive may include two motors according to any of the approaches described herein. In some approaches the two motors may be operated in unison, e.g., in a complimentary fashion. In other approaches a first of the motors may be used during normal use of the tape drive while the second motor is maintained as a backup motor, e.g., for when the first motor fails. In still other approaches, a first motor may be used to transition a magnetic tape in a “forward direction” from the supply reel to the take-up reel, while the second motor is used to transition the magnetic tape in a “backward direction” from the take-up reel to the supply reel. 
     Implementing various ones of the approaches included herein are desirably able to reduce motor disturbances being transmitted through the deck casting in tape drives and/or other similar systems. By insulating the stator from a surrounding environment which is preferably stationary (e.g., such as a magnetic tape head in the same tape drive) using isolation mounts as described above, the disturbances transmitted by the reaction forces emitted from a brushless DC motor can be significantly reduced compared to conventional products. The insulation of kinetic energy and general spacing (e.g., gap) that the isolation mounts provide between the stator and a surrounding environment allows the stator to vibrate and/or rotate (e.g., on the order of a few micrometers) without allowing these oscillations to be transmitted to the surrounding environment. Rather, these disturbances are absorbed by the isolation mounts and/or are otherwise confined to the stator level, thereby insulting the brushless DC motor from having an undesirable effect on the surrounding environment. Moreover, these improvements may be achieved for both internally and externally supported brushless DC motors. 
     The present invention may be a system, a method, and/or a computer program product. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a ROM, an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
     Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention. 
     Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     Moreover, a system according to various embodiments may include a processor and logic integrated with and/or executable by the processor, the logic being configured to perform one or more of the process steps recited herein. By integrated with, what is meant is that the processor has logic embedded therewith as hardware logic, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc. By executable by the processor, what is meant is that the logic is hardware logic; software logic such as firmware, part of an operating system, part of an application program; etc., or some combination of hardware and software logic that is accessible by the processor and configured to cause the processor to perform some functionality upon execution by the processor. Software logic may be stored on local and/or remote memory of any memory type, as known in the art. Any processor known in the art may be used, such as a software processor module and/or a hardware processor such as an ASIC, a FPGA, a central processing unit (CPU), an integrated circuit (IC), etc. 
     It will be clear that the various features of the foregoing systems and/or methodologies may be combined in any way, creating a plurality of combinations from the descriptions presented above. 
     It will be further appreciated that embodiments of the present invention may be provided in the form of a service deployed on behalf of a customer. 
     The inventive concepts disclosed herein have been presented by way of example to illustrate the myriad features thereof in a plurality of illustrative scenarios, embodiments, and/or implementations. It should be appreciated that the concepts generally disclosed are to be considered as modular, and may be implemented in any combination, permutation, or synthesis thereof. In addition, any modification, alteration, or equivalent of the presently disclosed features, functions, and concepts that would be appreciated by a person having ordinary skill in the art upon reading the instant descriptions should also be considered within the scope of this disclosure. 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of an embodiment of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.