Patent Publication Number: US-11393498-B2

Title: Head assembly with suspension system for a tape embedded drive

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 16/365,034, filed on Mar. 26, 2019, issuing as U.S. Pat. No. 10,991,390, entitled HEAD ASSEMBLY WITH SUSPENSION SYSTEM FOR A TAPE EMBEDDED DRIVE, which claims priority to U.S. Provisional Patent Application Ser. No. 62/803,366, filed Feb. 8, 2019, entitled TAPE EMBEDDED DRIVE, and U.S. Provisional Patent Application Ser. No. 62/816,860, filed Mar. 11, 2019, entitled TAPE EMBEDDED DRIVE, the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Field 
     This disclosure relates to tape-based data storage devices. More particularly, the disclosure relates to a data storage device with an embedded tape-based reading and writing mechanism. 
     Description of Related Art 
     In certain computing systems, tape storage systems comprise of a tape drive and tape cartridges or cassettes that store tape media (also called tape film or magnetic tape). The tape drive performs writing or reading of data in the cartridges or cassettes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments are depicted in the accompanying drawings for illustrative purposes, and should in no way be interpreted as limiting the scope of this disclosure. In addition, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. 
         FIGS. 1A-1C  illustrate a perspective exploded view and a simplified top down and side profile view of a tape embedded drive, in accordance with some embodiments. 
         FIG. 2  illustrates a top perspective view of a Printed Circuit Board Assembly (PCBA) of the tape embedded drive, in accordance with some embodiments. 
         FIGS. 3A-3B  illustrate possible placement locations of the tape reel(s) within the casing, in accordance with some embodiments. 
         FIG. 4  illustrates a perspective view of a 3.5 inch form factor tape embedded drive and a Linear Tape-Open (LTO) tape cassette, in accordance with some embodiments. 
         FIG. 5  illustrates a head assembly of the tape embedded drive, in accordance with some embodiments. 
         FIG. 6  illustrates an LTO head bar and a head bar for the tape embedded drive, in accordance with some embodiments. 
         FIGS. 7A-7B  illustrate perspective and facing views of another head assembly, in accordance with some embodiments. 
         FIGS. 8A-8B  illustrate perspective and facing views of a head assembly using a suspension system, in accordance with some embodiments. 
         FIGS. 9A-9B  illustrate perspective and facing views of a head assembly using a push-pull suspension system, in accordance with some embodiments. 
         FIGS. 10A-10C  illustrate a perspective view, a first side profile view, and a second side profile view of another embodiment of the head assembly comprising a head gimbal assembly, in accordance with some embodiments. 
         FIG. 11  illustrates a control block diagram for a servo-mechanical system of the tape embedded drive, in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     While certain embodiments are described, these embodiments are presented by way of example only, and are not intended to limit the scope of protection. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the scope of protection. 
     Although the principles disclosed herein may be applicable to any suitable or practical data storage system or environment, for convenience, certain embodiments are disclosed herein in the context of tape-based data storage systems. 
     Tape data storage is a system for storing digital information on magnetic tape using digital recording. Tape storage media is most commonly packaged in cartridges and cassettes. A tape drive performs writing or reading of data in the cartridges or cassettes. Autoloaders and tape libraries can be used to automate cartridge handling by moving cartridges/cassettes from a library of cartridges to the tape drive and vice versa. A common cassette-based format is LTO, which comes in a variety of densities. 
     In the context of magnetic tape, the term cassette usually refers to an enclosure that holds two reels with a single span of magnetic tape. The term cartridge is more generic, but frequently means a single reel of tape in a plastic enclosure. For convenience, the disclosure will refer to cassettes, but the described technology can also be applied to cartridges. 
     The type of packaging is a large determinant of the load and unload times as well as the length of tape that can be held. A tape drive that uses a single reel cartridge has a take-up reel in the drive while cassettes have the take-up reel in the cassette. A tape drive (or “transport” or “deck”) uses precisely controlled motors to wind the tape from one reel to the other, passing a read/write head as it does. 
     Current tape drive library systems have several deficiencies. As tapes are open to the environment, the tape storage facility (e.g., data center) needs to control the humidity and temperature to ensure the reliability of the tape. Such environmental maintenance can be expensive. In addition, even with such maintenance, long-term reliability can still be a problem. For example, variances in temperature or contamination from dust could affect the reliability of the tape drives. 
     In addition, the robotics used to move a tape cassette from a tape holder in the library to the tape drive system can cause additional delay in reading. For example, access time for both robotics (about average 50 s) and tape drive (about average 50 s) can be about 100 s. 
     Furthermore, the tape drive system uses an up/down stepping motor and voice coil motor (VCM), called dual stage motors, to move a large writer and reader head bar. At higher tracks per inch (TPI), the large head bar limits the accuracy possible with the dual stage motors. Additionally, the tape drive system needs to support multiple generations of cassettes. The tape drive system may need to write and read data for several types of tape film vendors and recording generations. Maintaining compatibility can limit the possibility of technology improvement. 
     Tape Embedded Drive Overview 
     One possible solution to these problems is a tape embedded drive, embodiments of which are discussed below. The tape embedded drive is, in some embodiments, a cassette that integrates the tape media and the head(s) for reading and writing. Further, the cassette can utilize, for example, the 3.5 inch form factor common to hard disk drives (HDD). By using the 3.5 inch form factor, technologies developed for HDDs such as controllers and sealed drive technology can be adapted or otherwise utilized for tape drives. For example, a similar PCBA used in HDD drives could be used, providing a SATA or a SAS interface to the host. Further, the PCBA can comprise a system-on-a-chip (SoC) and/or other control circuitry, including, for example, data read channel, memory, motor driver(s) and actuator driver(s). Integrating the head technology can eliminate the need for maintaining a tape library system, including the associated maintenance costs. 
     In addition, using a standardized form factor such as the 3.5 inch form factor can provide better integration with existing data center infrastructure. HDDs are commonly used in data centers for storage, with specialized racks and servers designed to utilize 3.5 inch form factor HDDs. By using the 3.5 inch form factor, the tape embedded drive can simplify the maintenance and infrastructure needs of data centers. Rather than having a second set of infrastructure for supporting tape drives, the data center could utilize the same infrastructure to support both HDDs and tape embedded drives such as those described in this disclosure. In certain other embodiments, the same integrated approach can be applied to a non-3.5 inch form factor construction. For example, a 2.5 inch or 5.25 inch form factor may be used, or another generally rectangular form factor may be used. Using a 2.5 inch or 5.25 inch form factor may also provide the same infrastructure and other benefits mentioned above with respect to the 3.5 inch form factor. 
       FIGS. 1A-1C  illustrate a perspective exploded view and a simplified top down and side profile view of a tape embedded drive  100 , according to certain embodiments. Focusing on  FIG. 1B  for example, the tape embedded drive comprises a casing  105 , one or more tape reels  110 , tape media  115 , one or more motors (e.g., a stepping motor  120  (also known as a stepper motor), a voice coil motor  125 , etc.), a head assembly  130  with one or more read and write heads, tape guides/rollers  135   a ,  135   b  and PCBA  155  ( FIG. 1C ). In an embodiment, most of the components are within an interior cavity of the casing, except the PCBA which is mounted on an external surface of the casing. The same components are illustrated in a perspective view in  FIG. 1A . 
     In the illustrated embodiment, two tape reels  110  are placed in the interior cavity of the casing, with the center of the two tape reels on the same level in the cavity and with the head assembly  130  located in the middle and below of the two tape reels. Tape reel motors  140  located in the spindles of the tape reels can operate to wind and unwind the tape film in the tape reels. Each tape reel may also incorporate a tape folder to help the tape film be neatly wound onto the reel. The tape media may be made via a sputtering process to provide improved areal density. 
     Tape film from the tape reels are biased against the guides/rollers  135   a ,  135   b  and are movably passed along the head assembly  130  by movement of the reels. The illustrated embodiment shows four guides/rollers  135   a ,  135   b , with the two guides/rollers  135   a  furthest away from the head assembly  130  serving to change the direction of the film and the two guides/rollers  135   b  closest to the head assembly  130  pressing the film against the head assembly  130 . 
     As shown in  FIG. 1A , in some embodiments, the guides/rollers  135  utilize the same structure. In other embodiments, as shown in  FIG. 1B , the guides/rollers  135  may have more specialized shapes and differ from each other based on function. Furthermore, a lesser or greater number of rollers could be used. For example, the two functional rollers may be cylindrical in shape, while the two functional guides may be flat-sided (e.g., rectangular prism) or clip shaped with two prongs and the film moving between the prongs of the clip. 
     The voice coil motor and stepping motor can variably position the tape head(s) transversely with respect to the width of the recording tape. The stepping motor can provide coarse movement while the voice coil motor can provide finer actuation of the head(s). In an embodiment, servo data can be written to the tape to aid in more accurate positioning of the head(s) along the tape film. 
     In addition, the casing  105  can comprise one or more particle filters  141  and/or desiccants  142  ( FIG. 1A ) to help maintain the environment in the casing. For example, if the casing is not airtight, the particle filters may be placed where airflow is expected. The particle filters and/or desiccants can be placed in one or more of the corners or any other convenient place away from the moving internal components. For example, the moving reels may generate internal airflow as the tape winds/unwinds, and the particle filters can be placed within that airflow. 
     There is a wide variety possible in the placement of the internal components of the tape embedded drive  100  within the casing. In particular, as the head mechanism is internal to the casing in certain embodiments, the film does not ever have to be exposed outside of the casing, such as in conventional tape drives. Thus, the tape film does not need to be routed along the edge of the casing and can be freely routed in more compact or otherwise more efficient ways within the casing. Similarly, the head(s) and tape reels can be placed in a variety of locations to achieve a more efficient layout, as there is no design requirement to provide external access to these components. 
     As shown in  FIG. 1C , the casing  105  comprises a cover  150  and a base  145 . The PCBA  155  is attached to the bottom, on an external surface of the casing  105 , opposite the cover  150 . As the PCBA is made of solid state electronics, environmental issues are less of a concern, so it does not need to be placed inside the casing  105 . That leaves room inside the casing for other components, particularly the moving components and film media that benefit from a more protected environment. 
     In some embodiments the tape embedded drive  100  is sealed. Sealing can mean the drive is hermetically sealed or simply enclosed without necessarily being airtight. Sealing the drive can be good for tape film winding stability, tape film reliability, and tape head reliability. Desiccant may be used to limit humidity inside the casing. 
     In one embodiment, the cover  150  is used to hermetically seal the tape embedded drive. For example, the drive  100  may be hermetically sealed for environmental control by attaching (e.g., laser welding, adhesive, etc.) the cover to the base  145 . The drive  100  may be filled by helium, nitrogen, hydrogen or some other typically inert gas. 
     In some embodiments, other components can be added to the tape embedded drive  100 . For example, a pre-amp for the heads can be added to tape embedded drive. The pre-amp may be located on the PCBA  155 , in the head assembly  130 , or in another location. In general, placing the pre-amp closer to the heads can have a greater effect on the read and write signals in terms of signal-to-noise ratio (SNR). In other embodiments, some of the components could be removed. For example, the filters  141  or the desiccant  142  may be left out. 
       FIG. 2  illustrates a top perspective view of the PCBA  155  of the tape embedded drive  100 , according to certain embodiments. The PCBA  155  is attached to the bottom surface of the casing, with a connector  205  attaching to contacts or an interface on the bottom surface electrically/electronically connected to internal components in the casing. For example, the contacts or interface may be electrically connected to one or more motors and/or actuators within the casing. In an embodiment, the contacts/interface are built into the casing without compromising an air tight seal of the casing. In some embodiments, the connector  205  can be an electrical feed-through electrically connecting components inside the casing to those on the PCBA, while maintaining sealing of the casing. For example, an electrical feed-through similar to those found in sealed helium disk drives can be used, such as that described in U.S. Pat. No. 9,672,870, titled “Sealed bulkhead electrical feed-through X-Y positioning control,” issued on Jun. 6, 2017 and assigned to the assignee of this disclosure, the disclosure of which is incorporated by reference. 
     The PCBA  155  can include various components, such as one or more controllers, one or more connectors  205 , an SoC  210 , one or more data interfaces  215  (e.g., Serial ATA (SATA), Serial Attached SCSI (SAS), non-volatile memory express (NVMe) or the like), memory  220 , a Power Large Scale Integration (PLSI)  225 , and/or data read channel controller  230 . One or more cutouts  235  can be added in the PCBA to provide additional space for tape reel motors, if needed. For example, the portion of the casing above the tape reel motors  140  may be raised to provide additional space for the motors. By providing cutouts  235 , the thickness of the tape embedded drive  100  can be reduced as the PCBA  155  can surround the raised portion of the casing. 
     The PCBA can extend along the entire bottom exterior surface of the casing  105  or may only partially extend along the surface, depending on how much space the various components need. In some embodiments, a second PCBA may be located internally in the casing  105  and be in communication with the first PCBA  155 , for example, via the connector  205 . 
     In some embodiments, a controller on the PCBA controls the read and write operations of the tape embedded drive  100 . The controller can engage the tape spool motors and cause the tape spools to wind the tape film forward or backwards. The controller can use the stepping motor and the voice coil motor to control placement of the head(s) over the tape film. The controller can also control output/input of data to or from the tape embedded drive  100  through the one or more interfaces  215  such as SATA or SAS. 
       FIGS. 3A-3B  illustrate possible placement locations of the tape reel(s) within the casing. As discussed above, the enclosed nature of the tape embedded drive  100  allows great leeway in placement of the internal components.  FIG. 3A  shows a placement of the tape reels  110   a ,  110   b  essentially along the same horizontal line. The reels are close to a top edge  305  of the casing, providing space along the bottom edge  310  of the casing for other internal components, such as motors and the head(s). 
       FIG. 3B  shows a placement of the tape reels diagonally from each other. The right tape reel  110   b  is located on the top right corner of the casing, with the left tape reel  110   a  on the bottom left corner of the casing. Space along the bottom right corner  315  and/or the top left corner of the casing is left for other internal components, such as motors and the head(s). In another embodiment, the reels can be located in the top left corner and the bottom right corner, with space left over in the bottom left corner and/or top right corner. 
     Dimension Considerations 
       FIG. 4  illustrates a perspective view of a 3.5 inch form factor tape embedded drive  100  and an LTO tape cassette, according to certain embodiments. In one embodiment, the tape embedded drive  100  has a length of 147 mm, a width of 102 mm and a height of 26 mm. An LTO cassette  405  has dimensions of a length of 125 mm, a width of 109 mm and a height of 25 mm. While the above discloses one set of possible dimensions for the tape embedded drive, other embodiments may have different dimensions. For example, the height might be doubled or otherwise increased (e.g., to about 52 mm) to allow larger tape film with a larger data capacity to be used. 
     The size (length×wide×height) of the tape embedded drive with PCBA can be optimized by access time and storage capacity. For faster access time, the tape film length should be shorter. Shorter tape film length can lead to shorter length and/or width size of the casing for the tape embedded drive, but at the potential cost of reduced total data capacity. For increased capacity, the casing can be lengthened in width and/or length to store longer total tape length, but at the potential cost of longer access time. 
     In some embodiments, the tape film width may be increased from the standard 12.65 mm used in LTO cassettes to a wider film. Increasing the tape width can increase capacity without necessarily having much effect on access time, as the overall tape length can stay the same. 
     Table 1 illustrates one possible embodiment for the tape film measurements of the tape embedded drive  100 , in comparison to LTO tape measurements. Based on tape thickness, tape length can be calculated to be about 592 m, which is about 60% of the length of a standard LTO tape film. For reference, current LTO tape cassette (125 mm×109 mm×25 mm) has about 960 m of tape film length in the cassette (LTO-7 spec). 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                 Tape  
               
               
                   
                   
                 LTO-7 
                 embedded drive 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Outer diameter (mm) 
                 91.9 
                 68.0 
               
               
                   
                 Inner diameter (mm) 
                 40.0 
                 20.0 
               
               
                   
                 Tape thickness (um) 
                 5.6 
                 5.6 
               
               
                   
                 Tape length (m) 
                 960 
                 592 
               
               
                   
                   
               
            
           
         
       
     
     In an LTO cassette, with a 7 m/s tape wind up and a tape length of 1098 m, the average seek time is about 1098/3/7˜=52 s, assuming that a ⅓ length seek time represents average seek time. Assuming an average robotics handling speed in the library system of 50 s, then total average data access time is about 100 s. On the other hand, some embodiments of the tape embedded drive, in a 3.5 inch form factor, can have an access time of 592/3/20˜=10 s for average seek time. With a shorter tape length and hence smaller tape mass, 10 m/s, 15 m/s, and 20 m/s tape wind up could be achieved. Further, there may be no or at least less backlash due to inertial rotation from each tape reel motor. 
     While the above discusses the tape embedded drive  100  as having a casing with a 3.5 inch form factor like that of HDDs, the tape embedded drive  100  can use other form factors. For example, if tape technology becomes sufficiently miniaturized in the future, then the tape embedded drive could use a 2.5 inch drive form factor, like that used by laptop HDDs. In some embodiments where larger sizes are desired, the tape embedded drive  100  can use a 5.25 drive form factor for the casing, such as that used by computer CD-ROMs. Further, the tape embedded drive  100  can use the 3.5 inch form factor with some variations. For example, the drive may be slightly longer/shorter, slightly thicker/thinner, or the like. Even with slight differences in dimensions or placement of data/power interfaces, the drive  100  may still be compatible with existing 3.5 inch based infrastructure found in various computer equipment, such as racks and servers. 
     Head Assembly 
       FIG. 5  illustrates a head assembly  500  of the tape embedded drive  100 , according to certain embodiments. The head assembly  500  comprises a multi-stage actuator for moving the head assembly. In some embodiments, the multi-stage actuator comprises a stepping motor  505  (first stage), a voice coil motor  510  (second stage) comprising a coil  529  and magnet  530  and a piezoelectric actuator  515  (third stage) which can provide coarse, fine, and ultra-fine actuation, respectively, for up/down movement of a head bar  520 . In an embodiment, the piezoelectric actuator is a lead zirconate titanate (PZT) actuator (e.g., shear PZT). By using a 3-stage motor, the movement of the head bar  520  can be more precise. With greater precision, more channels can be supported on the tape film, potentially allowing for greater data density on the tape film. In one embodiment, the head bar comprises heads in a write-read-write layout, similar in layout to conventional tape heads. In another embodiment, the head bar comprises two heads in a read-write layout, similar in layout to HDD heads. 
     The head assembly  500  can further comprise a screw shaft  525  connecting an actuator block  526  to the stepping motor. The screw shaft  525  and guide shafts  524 ,  540  can facilitate movement of the actuator block by the stepping motor  505 . In some embodiments, a different number of guide shafts are used (e.g., 0, 1, 3+). For example, smaller or lighter actuator blocks may need less support during movement and use only one or even no guide shafts. Meanwhile, larger or heavier actuator blocks could use additional guide shafts or multiple screw shafts. 
     A suspension assembly  528  can connect the head bar  520  to the actuator block  526 . In one embodiment, the suspension assembly includes a mounting plate, a load beam, and a laminated flexure to carry the electrical signals to and from the read and write heads in the head bar. The suspension assembly  528  can also include a coil  529  through which a controlled electrical current is passed. The coil  529  interacts with one or more magnets  530  attached to the actuator block  526  to form a voice coil motor  510  for controllably moving the head bar  520 . 
     In an embodiment, a head support block  535  connects the head bar  520  and piezoelectric actuator  515  to the suspension assembly  528 . The head support block  535  can comprise a clamp  536  to secure the head bar  520  and the piezoelectric actuator  515  and a supporting structure  537  perpendicular to the clamp to connect the base to the suspension assembly  528 . In an embodiment, the head support block and the actuator form a suspension system that allows the head bar  520  to move across the width of the tape media, in conjunction with the control provided by the voice coil motor  510  and the stepping motor  505 . 
     Note also that the piezoelectric actuator  515  may optionally be a multilayer piezoelectric element, comprising a plurality of piezoelectric material layers sandwiched between conductive (e.g., gold) electrode layers. The piezoelectric actuator  515  may optionally comprise one or more of the many known piezoelectric materials, for example, lead zirconate titanate, lead scandium tantalite, lanthanum gallium silicate, lithium tantalite, barium titanate, gallium phosphate and/or potassium sodium tartrate. 
     In one embodiment, the piezoelectric actuator  515  extends or contracts along a second axis. The actuator  515  can push the head bar  520  towards the tape media or pull the head(s) away from the tape media. In one embodiment, a heater (e.g., heating coil) may be incorporated into the head bar  520  in order to cause the head(s) to move closer to the tape film. A touchdown sensor could also be incorporated into the head bar to detect head-film contact and prevent the head bar from touching the tape film. 
     By allowing the head(s) to move closer to the tape film, the signal strength can be increased. In addition, by allowing the head bar to move away from the tape media, a fast-forward or fast-rewind function can be enabled for the tape embedded drive  100 . As the head bar is further away from the media, the chances of the media hitting the head bar is decreased even if the tape media is moving faster. By avoiding contact, the reliability of the read and write heads and/or the tape media are maintained. 
     In order to better secure the head assembly  500  to the casing  105 , a second guide shaft  540  may be used. In one embodiment, the first guide shaft  524  is on one side of the actuator block  526  with the second guide shaft  540  on the opposite end of the actuator block  526 . 
     In one implementation, movement of the head bar  520  is accomplished in a 3-stage action. First, the stepping motor makes the screw shaft  525  rotate, causing the actuator block to move up and down the first guide shaft  524  and the second guide shaft  540 . This causes the head bar to move across (up and down) the width of a tape film. When current is applied to the VCM coil, the head support block also goes up and down, while being supported by the suspension assembly. When voltage is applied to the piezoelectric actuator  515 , the head(s) again move up and down. Working in tandem, the 3-stage action can move the head bar across (up and down) the width of the tape film in coarse, fine or very fine increments. In one embodiment, the 3 stages of movement proceed at around a 30,000/10,000/1 ratio, with the stepping motor  505  capable of moving up to 12.65 mm, the VCM  510  capable of moving up to 4 mm and the piezoelectric actuator  515  capable of moving up to 0.4 μm. 
       FIG. 6  illustrates an LTO head bar  605  and a head bar  610  for the tape embedded drive  100 , according to certain embodiments. LTO cassettes only have a stepping motor and a voice coil motor to actuate the head bar.  FIG. 6  shows the relationship between tape width and tape head bar length for LTO and for an embodiment of the tape embedded drive. 
     Multiple writers and readers can be located in a head bar. For example, a tape bar could have 1-10 reader heads and/or 1-10 writer heads. Typically, a tape head bar uses a writer-reader-writer layout. However, other layouts, such as writer-reader-reader-writer could be used. In some embodiments, using two or more readers provides better signal-to-noise ratio (SNR), allowing for higher TPI. 
     Tape recording uses head film contact technology for recording. Typically, an LTO tape uses four data bands on the film, in which the head(s) are moved to four different locations up and down the width of the tape. The stepping motor is used to move to each of the four locations, with the voice coil motor handling finer actuation within each location. Thus, an LTO cassette uses a longer head bar length (e.g. 22.4 mm) than the tape width (12.65 mm) so that the tape width is covered by the head bar in each of the four locations it may move to. 
     Due to the heavy mass of the longer head bar  605 , wider head reader width and limited movement granularity of the stepping and voice coil motors, the track density on the film for an LTO cassette is limited. An LTO-7 track pitch is 10.7k TPI (2.37 μm). 
     In one embodiment, the tape embedded drive  100  comprises a significantly smaller head bar  610  than an LTO head bar  605 , such as a head bar  610  of about 4 mm in length. With a shorter head bar length and corresponding less mass, the head bar can be moved up and down by PZT ultra-fine actuation. In an embodiment, the head assembly is attached to the PZT actuator (as discussed in  FIG. 5 ), which is located on an assembly attached to an actuatable portion of the voice coil motor, which in turn is on an assembly attached to an actuatable portion of the stepping motor. In one embodiment, the PZT actuator is moved by the voice coil motor and the voice coil motor is in turn moved by the stepping motor. 
     While the above discusses head bar sizes of about 4 mm, other sizes are possible, such as about 3 mm, about 5 mm or even other sizes. In some embodiments, the head bar is significantly smaller than the tape width. For example, the head bar may be less than half or even less than a quarter of the width of the tape media. 
     In one embodiment, two tape guides  615  are located on both sides of the tape assembly. The tape guides limit the movement of the tape and provide better stability when the head assembly is moving over the tape film. In other embodiments, only a single tape guide placed either before or after the head assembly may be utilized. 
     The head bar  610  can be supported by an HDD-like gimbal assembly or suspension assembly (as discussed in  FIG. 5 ). This can provide gentler and/or more stable head to film contact, potentially providing better reliability for reading and/or writing. The suspension assembly could use a variety of materials, such as stainless steel or the like. 
     Head Assembly Embodiments 
       FIGS. 7-10C  illustrate various different embodiments of the head assembly of the tape embedded drive  100 . These are just some variations; other variations could work with the tape embedded drive  100 . For example, the following examples use piezoelectric actuators, such as shear or push-pull PZTs. However, other types of actuators with similar performance characteristics could be used. In another example, different numbers of piezoelectric actuators (e.g., 1, 2, 3, 4, etc.) could be used instead of the numbers shown. 
       FIGS. 7A-7B  illustrate perspective and facing views of an embodiment of the head assembly  700 . While the head assembly  700  is similar to the head assembly of  FIG. 5 , the piezoelectric actuator is split into two bars or sections  715   a ,  715   b , with a cutout in the middle. The piezoelectric actuators move the head bar  720  across the width of the tape media, as shown by the dashed arrows in  FIG. 7B . Reducing the amount of piezoelectric material can reduce weight, which is beneficial to movement of the head bar  720 . For example, a lighter head bar can reduce the electrical power needed to actuate the head bar. Reducing the material can also reduce production costs. 
       FIGS. 8A-8B  illustrate perspective and facing views of another embodiment of the head assembly  800  using a suspension system  840 . The head assembly  800  is similar to the head assembly of  FIGS. 7A-7B , with the addition of the suspension system  840 . The suspension system  840  can aid the head bar  820  in maintaining soft-touch contact with the tape film. As the tape film moves past the head bar  820 , the tape may fluctuate slightly with respect to the touching head surface. The suspension system  840  can compensate for those fluctuations and enable the head to remain in contact with the tape film. This can increase read/write performance, reduce potential damage to the tape film, and/or enhance read/write reliability. 
     In one embodiment, the suspension system  840  comprises a frame. The frame can be connected to a support structure  841  like the head support block described in  FIG. 5  on one side. The head bar  820  can be connected to the other side of the frame. 
     In some embodiments, the cutouts in the suspension system  840  can be enlarged or decreased in order to change the tension of the suspension system  840 . Changing the tension can affect the amount of movement of the head bar  820  when the piezoelectric actuators move the head bar across the tape media, as shown by the dashed arrows in  FIG. 8B . 
       FIGS. 9A-9B  illustrate perspective and facing views of another embodiment of the head assembly  900  using a push-pull suspension system. Push-pull actuators generally use less voltage than shear actuators. The push-pull suspension system comprises a push actuator  941 , a pull actuator  942  and a frame  943 . In one embodiment, the push actuator, the pull actuator, and a plurality of suspension wires connect the head bar  920  to the frame  943  connected to a support structure  944 . 
     Working in tandem, the push and pull actuators can move the suspended head up and down relative to the width of the tape, as shown by the dashed arrows in  FIG. 9B . For example, when the push actuator  941  contracts, the pull actuator  942  expands, thereby pushing the head to one direction (up). When the push actuator  941  expands and the pull actuator  942  contracts, the head is pushed in the opposite direction (down). In an embodiment, the push and pull actuators are PZTs. 
     The suspension system can also comprise wire suspensions  945   a ,  945   b  for movably supporting the head(s). In an embodiment, the wire suspensions  945   a ,  945   b  are made of a flexible material that can be easily moved by the push and pull actuators. In the illustrated embodiment, two suspension wires are placed on each side of the head(s). 
     The design of the wire suspensions may be different to account for the desired movement of the head bar. For example, the push pull actuators  941 ,  942  are moving the head bar across the width of the tape media, as shown by the dashed arrows. In one embodiment, a first suspension wire type  945   a  is configured to facilitate the up-down movement, for example, by having a loop section configured to compress along the up-down movement. In one embodiment, a second suspension wire type  945   b  is configured to reduce lateral movement during the up-down movement. For example, the second suspension wire may be stiffer, utilize a higher tensile material, and/or utilize a shape (e.g., a “W” shape) that reduces compression along the direction perpendicular to the up-down motion. 
     Push-pull actuators designs used in HDDs can be adapted for use in tape drives, as described above. Push-pull designs have high reliability and low production cost, making them a good fit for embodiments of the tape embedded drive  100 . 
       FIGS. 10A-10C  illustrate a perspective view ( FIG. 10A ), a first side profile view ( FIG. 10B ) and a second side profile view ( FIG. 10C ) of another embodiment of the head assembly  1000  comprising a head gimbal assembly (HGA)  1050  adapted from HDD HGAs.  FIG. 10C  is a side profile view of  FIG. 10B  rotated 90 degrees along an axis. The HGA  1050  comprises an elongated suspension  1051  comprising a top end and a base end. The suspension  1051  can support, on its top end, a head  1020  (or multiple ones) and head slider (or multiple ones) with an air bearing system  1052 . 
     The elongated suspension  1051  can be connected, at its base end, to a supporting structure  1053  by one or more actuators  1054 ,  1055  and a spring-type clamp  1056 . In the illustrated embodiment, the one or more actuators are a push-pull actuator, with a first actuator  1054  and a second actuator  1055  connecting the base of the suspension  1051  to the spring-type clamp  1056  that connects the suspension  1051  to the supporting structure  1053 . 
     In an embodiment, the first actuator  1054  and the second actuator  1055  are PZT actuators. As shown in  FIG. 10C , when the first actuator  1054  expands and the second actuator  1055  contracts, the head(s) move to the left. When the first actuator  1054  contracts and the second actuator  1055  expands, the head(s) move to the right. 
     Control System 
       FIG. 11  illustrates a control block diagram for a servo-mechanical system  1100  of the tape embedded drive  100 , according to certain embodiments. The control logic for the system may be implemented as a process in one or more controllers of the tape embedded drive  100 , such as the SoC and/or PLSI in the PCBA and used to control one or more motors and/or actuators. 
     In an embodiment, a stepping motor controller  1105 , a PZT controller  1107  and a VCM controller  1110  work together to control a stepping motor  1115 , a PZT actuator  1120 , and a VCM  1125  to coordinate the movement of the head(s) in response to a target command. 
     As discussed above, the stepping motor  1115  can provide coarse movement, the VCM  1125  can provide fine movement, and the PZT actuator  1120  can provide very fine movement. For example, assuming a 12.65 mm tape width, the stepping motor stroke may be about 12.65 mm, with the VCM stroke at about 4 mm, and the PZT stroke at about 0.4 μm. In this embodiment, that creates a movement ratio of about 30,000:10,000:1 (stepping motor/VCM/PZT actuator). In other embodiments, the ratios could be different based on the performance specification of the motors and actuators. 
     A first control signal  1130  is sent from the stepping motor controller to the stepping motor. The head(s) are then moved in a coarse movement. In an embodiment, a head position sensor detects the heads&#39; position after the first movement and provides a positive error signal (PES) to the VCM and PZT controllers. In response, the VCM and PZT controllers can further move the head(s) in a fine and a very fine movement respectively, if needed, to place the head(s) into the desired position. 
     A first amplifier  1133  can be positioned in between the PZT controller  1107  and the PZT actuator  1120  to amplify a second control signal  1135 . A second amplifier  1138  can be positioned in between the VCM controller  1110  and the VCM  1125  to amplify a third control signal  1140 . 
     In an embodiment, the PZT actuator  1120  and VCM  1125  move the head(s) serially. The VCM first moves the head(s) and then, if the head(s) are within a first threshold distance from the target position, the PZT actuator  1120  can take over movement of the head(s) for very fine movements. In another embodiment, the PZT actuator  1120  and the VCM  1125  may move the head(s) in parallel. It should be noted that although PZT is used throughout in the description of the control system of  FIG. 11 , as disclosed above other types of actuators may be used in place of PZTs, and the system of  FIG. 11  can be adapted accordingly in other embodiments. 
     Additional Embodiments 
     Those skilled in the art will appreciate that in some embodiments, other types of tape embed drive systems can be implemented while remaining within the scope of the present disclosure. In addition, the actual steps taken in the processes discussed herein may differ from those described or shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of protection. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the protection. For example, the various components illustrated in the figures may be implemented as software and/or firmware on a processor, ASIC/FPGA, or dedicated hardware. Also, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Although the present disclosure provides certain preferred embodiments and applications, other embodiments that are apparent to those of ordinary skill in the art, including embodiments which do not provide all of the features and advantages set forth herein, are also within the scope of this disclosure. Accordingly, the scope of the present disclosure is intended to be defined only by reference to the appended claims. 
     All of the processes described above may be embodied in, and fully automated via, software code modules executed by one or more general purpose or special purpose computers or processors. The code modules may be stored on any type of computer-readable medium or other computer storage device or collection of storage devices. Some or all of the methods may alternatively be embodied in specialized computer hardware.