Abstract:
A tape drive having a cartridge receiving area for receiving a cartridge containing a recording medium on a supply reel is disclosed. The tape drive has a take-up reel. The take-up reel includes a take-up rotatably mounted to the tape drive and a pair of flanges mounted on either side of the take-up hub. A magnetic read/write head is disposed between the cartridge receiving area and the take-up reel. A pair of fixed guide assemblies is disposed symmetrically about the magnetic read/write head. Each of the fixed guide assemblies has a fixed guide mount fixed to the tape drive, a fixed guide attached to a top of the fixed guide mount, and a spring/pressure pad having at least one pressure pad mounted to the fixed guide, wherein the pressure pad applies pressure to a top edge of the recording medium when the tape drive is operational. The tape drive also has a forward guide roller and a rearward guide roller disposed symmetrically about the magnetic read/write head. The forward guide roller is located between the cartridge receiving area and the one of the pair of fixed guide assemblies and the rearward guide roller is located between the take-up reel and the other of the fixed guide assemblies. Each of the forward guide roller and rearward guide roller includes a shaft mounted to the tape drive and a rotor disposed about the shaft.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 60/186,772, filed Mar. 3, 2000, the contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a magnetic tape drive device used in conjunction with single reel tape cartridges and, more particularly, to a tape path for such a tape drive device. 
     DESCRIPTION OF RELATED ART 
     Tape drive devices for storing magnetic data are well known in the art. In the forward move, tape is moved from a supply reel, which supplies the tape, to a take-up reel, which draws tape from the supply reel along the tape path and over the magnetic read/write head. In the reverse mode, tape is moved from the take-up reel to the supply reel. 
     Tape cartridge configurations for data storage generally fall into one of two categories. In the first category, both reels are located inside a single magazine or cartridge, that is, the supply reel and the take-up reel are contained within a single housing. In the forward read/write mode, the tape moves from the supply reel to the take-up reel in a single housing and vice versa in the reverse mode. The read/write head is located in the tape drive separate from the tape cartridge. Examples of such cartridges include quarter-inch cartridges (“QIC”), digital audio tape (“DAT”) cartridges, and audio/video cassettes. 
     The second category of tape cartridge configurations has only a single reel, generally the supply reel, in the cartridge or magazine. This type of cartridge is used with a tape drive having a take-up reel permanently housed in the tape drive unit. In such tape drives, the tape cartridge is inserted into the tape drive unit. The cartridge is then registered and the front end, or leader end, of the tape is transferred from the supply reel along the tape path of the tape drive to the take-up reel. The magnetic read/write head, which reads or writes to the tape, is located along the tape path and the take-up reel serves to draw the tape across the magnetic read/write head. Examples of such cartridges include DLT (Digital Linear Tape) cartridges made by Quantum, 3480/3490 cartridges made by IBM, and LTO (Linear Tape Open) cartridges to be made by Seagate Technologies, Inc., Hewlett Packard, and IBM. 
     There are a number of single reel tape cartridges available in the marketplace. Tape drives that work in conjunction with such cartridges have a take-up reel located inside the tape drive housing and should have a suitable tape path for proper tape handling. The tape paths of these tape drives provide many, if not all, of the following features: 
     a proper wrap angle to the read/write head; 
     the ability to filter out axial runout of the reels/motors as the tape moves from a reel to the head (i.e., the tape path must move the tape in a reasonably straight path); 
     minimization of, and the effects of, misalignment between the reels; 
     minimization of drops in the tape tension along tape guiding elements as the tape travels from one of the reels to the read/write head; 
     minimization of tape wear at the media surface and at its edges; 
     operation in a rapid start/stop mode; 
     minimization of shifting in the tape position when the tape changes from a forward direction to a reverse direction, or vice versa; 
     a suitable surface under varying humidity and temperature conditions to ensure that the tape does not stick to the guiding elements; and 
     a suitable surface to conduct electrostatic charges that build up on the tape surfaces. 
     To achieve the above features, tape paths generally have a combination of tape guiding elements or members. Examples of these guiding elements include flanged or flange-less guide rollers, fixed guides, and air bearing guides. 
     One known tape path is disclosed in U.S. Pat. No. 5,414,585, which uses a large number of tape guide rollers to guide the tape along the tape path from the supply reel to the take-up reel. One of the problems associated with this design is the large initial motor current that is required to overcome the mass moment of inertia of the rotating guide elements. As a result, for a rapid start/stop requirement, this device has present potential problems. 
     Moreover, depending on tolerances allowed during fabrication of this type of tape drive, each of the guide rollers may contribute to error in the tape path, rather than eliminate the error. Also, these tape guide rollers use precision ball bearings, which must be lubricated to reduce wear and, subsequently, raise the possibility of failure. The motors in these tape drives also must produce a certain amount of torque to overcome the drag produced by the rollers, thus requiring higher torque motors. 
     Another known tape drive with its associated tape path is described in U.S. Pat. No. 5,224,641 (also U.S. Pat. No. 4,842,177), in which the drive utilizes air bearing guides as its guide elements. Air bearing guides are advantageous in that they are highly reliable, provide excellent tape guiding, and result in very low stiction. There are problems, however, with air bearing guides because, foremost, they utilize an air pump and must have the necessary plumbing to get the air from the air pump to the air bearing. Modem computers, however, are very constrained with respect to space and tape drives must satisfy a certain form factor. As a result, if the form factor of the tape drive is small, then air bearing guides are not a good solution because of the space required to house the air pump and the associated plumbing elements. In addition, tape drives that utilize air bearing guides are very expensive. 
     Tape drives having tape paths that utilize only fixed guides are well known in the art, but have many problems. In such tape drives, a well designed tape path has a maximum length of tape between the supply reel and the take-up reel. Fixed guides produce friction in the tape path, a problem that is considerably more serious in humid environments. Stiction is exacerbated if the angle that the tape must wrap around the fixed guide (i.e., the “wrap angle”) is large and/or if the contact area is large. 
     SUMMARY OF THE INVENTION 
     There is a need for a single reel cartridge tape drive that fits into a limited space, i.e., fits within a limited form factor (e.g., the 5.25 inch form factor or 5.75″ wide×8″ deep). 
     These and other needs are met by an embodiment of the invention, which provides a tape drive having a cartridge receiving area adapted to receive a cartridge containing a recording medium on a supply reel. The tape drive has a take-up reel, a magnetic read/write head disposed between the cartridge receiving area and the take-up reel, a pair of fixed guide assemblies disposed symmetrically about the magnetic read/write head, and a forward guide roller and a rearward guide roller disposed symmetrically about the magnetic read/write head. The forward guide roller is located between the cartridge receiving area and the one of the pair of fixed guide assemblies and the rearward guide roller is located between the take-up reel and the other of the fixed guide assemblies. 
     Another preferred embodiment provides a tape drive having a cartridge receiving area for receiving a cartridge containing a recording medium on a supply reel is disclosed. The tape drive has take-up reel. The take-up reel includes a take-up rotatably mounted to the tape drive and a pair of flanges mounted on either side of the take-up hub. A magnetic read/write head is disposed between the cartridge receiving area and the take-up reel. A pair of fixed guide assemblies is disposed symmetrically about the magnetic read/write head. Each of the fixed guide assemblies has a fixed guide mount fixed to the tape drive, a fixed guide attached to a top of the fixed guide mount, and a spring/pressure pad having at least one pressure pad mounted to the fixed guide, wherein the pressure pad applies pressure to a top edge of the recording medium when the tape drive is operational. The tape drive also has a forward guide roller and a rearward guide roller disposed symmetrically about the magnetic read/write head. The forward guide roller is located between the cartridge receiving area and the one of the pair of fixed guide assemblies and the rearward guide roller is located between the take-up reel and the other of the fixed guide assemblies. Each of the forward guide roller and rearward guide roller includes a shaft mounted to the tape drive and a rotor disposed about the shaft. 
     Additional advantages and novel features of the invention are set forth in the following description and will become apparent to those of ordinary skill in the art from the following description or through practice of the invention. The advantages of the invention may be realized and attained through the instrumentalities and combinations pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following detailed description of the embodiments of the invention is best understood when read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a tape path for a single reel cartridge tape drive according to the invention; 
     FIG. 2 is a top view of the tape path of FIG. 1; 
     FIGS. 3A-3C are several views of the take-up reel assembly of FIG. 1; 
     FIGS. 4A-4C are several views of the forward guide roller assembly of FIG. 1; 
     FIGS. 5A and 5B are several views of the forward fixed guide assembly of FIG. 1; 
     FIGS. 6A and 6B are several views of the rearward fixed guide assembly of FIG. 1; and 
     FIGS. 7A-7C are several views of the rearward guide roller assembly of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, and initially to FIGS. 1 and 2, there will be seen a tape drive unit  100 . The tape drive unit comprises a main base plate  102  and a housing (not shown). A cartridge  104  containing the supply reel or cartridge reel  106  is inserted into a cartridge receiving area  107  of the tape drive  100 . A tape  108  is wound on the supply reel  106 . The cartridge  104  is equipped with a slot  110  that is covered by a door  112  when the cartridge  104  is not inserted into the drive  100 . The slot  110  allows the tape  108  to pass outside of the cartridge  104  when the drive  100  is in use. The door  112  protects the tape  108  when the cartridge  104  is not inserted in the tape drive  100 . The door  112  is opened by a mechanism (not shown) once it is inserted into the tape drive. 
     The tape drive  100  also has a take-up reel  200 , which is shown in more detail in FIGS. 8A-8C. The take-up reel  200  draws the tape  108  from the supply reel  106  along the tape path and winds the tape  108  in the forward read/write mode. The tape drive  100  also has a magnetic read/write head  114  that reads from and writes to the tape  108 . The tape  108  must be drawn across the magnetic read/write head  114  at a vertical location that does not change substantially across the entire length of the tape  108 . 
     Disposed on either side of the magnetic read/write head  114  are a guide roller assembly  300 ,  600  and a fixed guide assembly  400 ,  500 . The forward guide roller assembly  300  and the forward fixed guide assembly  400  are placed between the tape cartridge  104  and the magnetic read/write head assembly  114 . The rearward fixed guide assembly  500  and the rearward guide roller assembly  600  are disposed between the magnetic read/write head assembly  114  and the take-up reel  200 . In other words, as the tape  108  is drawn from the supply reel  106  to the take-up reel  200 , the tape  108  first passes the forward guide roller  300 , then the forward fixed guide  400 , the magnetic read/write head  114 , the rearward fixed guide  500 , and finally passes the rearward guide roller prior to being wound by the take-up reel assembly  200 . 
     The forward guide roller  300  is positioned in the vicinity of the slot of the cartridge. The forward guide roller  300  is positioned to ensure that the tape  108  exits properly from the cartridge, for instance, so that the tape  108  will not contact the cartridge as the cartridge reel goes from a fully loaded condition to an empty condition. Moreover, the location of the forward guide roller  300  provides suitable angles and ranges (preferably, 66 degrees at the beginning of the tape and 45 degrees at the end of the tape) around the guide roller  300  and provides a maximum distance between the supply reel  106  and the forward guide roller  300  and a maximum distance between the forward guide roller  300  and the forward fixed guide  400 . 
     The forward fixed guide  400  is positioned to provide the necessary wrap of the tape  108  at the magnetic read/write head  114 . Based on the geometry of the read/write head  114 , a certain wrap angle of the tape is necessary for a proper head tape interface. The correct wrap angle also limits tape surface wear and maintains the head air bearing effects. 
     The tape path is symmetrical about the read/write head assembly  114  to ensure that the tape  108  is subject to the same forces and the like, regardless of whether the tape drive  100  is operating in the forward mode or the reverse mode. In other words, the distance and tape path between the forward fixed guide  400  and the magnetic read/write head  114  are substantially identical to the distance and tape path between the rearward fixed guide  500  and the magnetic read/write head  114 . The distance and tape path between the forward guide roller  300  and the forward fixed guide  400  are substantially identical to the distance and tape path between the rearward guide roller  600  and the rearward fixed guide  500 . 
     As shown in FIGS. 3A-3C, the take-up reel comprises a take-up hub  202  with flanges  204 ,  206  disposed on either side of the hub  202 . The top flange  204  is mounted to the take-up hub  202  via a plurality of screws  208 . The screws  208  are inserted through a plurality of screw-holes  210  in the flange  204 . The screw-holes  210  are distributed substantially evenly about the inner periphery of the top flange  204 . The screws  208  are then inserted into the corresponding holes  212  in take-up hub  202  and tightened. 
     The bottom flange  206  is mounted to the take-up hub in substantially the same manner. That is, a plurality of screws  214  are inserted through a plurality of screw-holes  216  in the flange  206 . The screw-holes  216  are distributed substantially evenly about the inner periphery of the bottom flange  206 . The screws  214  are then inserted into the corresponding holes  218  in take-up hub  202  and then tightened firmly to hold the bottom flange  206  in place. 
     In the embodiment of FIGS. 3A-3C, there are five screws  208  fixing the top flange  204  to the take-up hub  202  and five screws fixing  214  fixing the bottom flange  206  to the take-up hub  202 . The arrangement of the screws  208 ,  214  ensures that the clamping force is evenly distributed across the flanges  204 ,  206 . Although five screws  208 ,  214  are shown, any number may be utilized so long as they are substantially evenly distributed about the inner periphery of each flange  204 ,  206 . Also, other types of connecting fasteners may be used rather than screws. 
     Because the flanges have openings  220 ,  222 , counterweights  224 ,  226  are inserted into the take-up hub  202 . The counterweights  224 ,  226  ensure that the weight of the take-up reel assembly  200  is well-balanced and that the take-up reel assembly  200  is not adversely affected by centrifugal forces and not subject to unnecessary vibrations. 
     There are several advantages to the depicted embodiment of the take-up reel  200 . Among these advantages is that each of the flanges  204 ,  206  has smooth and uninterrupted surfaces to minimize air turbulence as the flanges  204 ,  206  rotate during the forward or backward read/write modes of the tape drive  100 . A substantially laminar air flow results under the flanges  204 ,  206 , which greatly reduces unwanted movement of the tape  108  during rapid start/stop of the tape  108 . Moreover, each flange  204 ,  206 , as shown in FIG. 8C, is tapered to prevent the tape  108  from contacting the flanges  204 ,  206  during the read/write modes. As a result, the geometry of the take-up reel assembly  200  provides an excellent wind quality. 
     FIGS. 4A-4C show, in detail, the first guide roller  300 . The forward guide roller  300  includes a shaft  302 , which has an underside  305  that acts as a mounting surface for the forward guide roller  300 . The shaft  302  is attached to the main base plate  102  of the tape drive  100  via a screw (not shown). 
     Disposed about the shaft  302  is a rotor or sleeve  304 . The rotor  304  is supported by ball bearings  306 ,  308 , which are located at either end of the shaft  302 . A cover  310  is placed over a distal end of the shaft  302  to prevent contaminants from falling into the interior of the rotor  304  and the ball bearings  306 ,  308 . 
     The distal end of the shaft  302  is also equipped with a slot  312  (or anti-rotation mechanism) that is used to prevent the shaft  302  from rotating during installation of the first guide roller  300  onto the main base plate  102  of the tape drive  100 . For example, the head of a flat-head screw driver can be inserted into the slot  312  to prevent the shaft  302  from rotating while the screw (not shown) is inserted into the underside  305  at the proximal end of the shaft  302  through the main base plate  102 . 
     During the forward read/write mode, the tape  108  is drawn from the supply reel  106  across the first guide roller  300 . As the tape  108  is drawn closer to the take-up reel  200 , the tape path next comprises the forward fixed guide assembly  400 , which is shown in detail in FIGS. 5A and 5B. The forward fixed guide assembly  400  is located on the main base plate  102  using a plurality of locating pins (not shown). 
     The forward fixed guide assembly  400  comprises a fixed guide mount  402  for mounting the forward fixed guide assembly  400  to the main base plate  102  of the tape drive  100 . A fixed guide  404  is mounted to the fixed guide mount  402  via screws (not shown), for example. A spring  406  is mounted to the fixed guide  404  and a spring/pressure pad assembly  408  having pressure pads  410 ,  412  is mounted thereto. A cover  414  is secured to the top of the forward fixed guide assembly  400 . 
     The top surface  416  of the fixed guide mount  402  acts as a reference surface for the tape  108 . In other words, the tape path is designed such that the bottom edge of the tape  108  travels along the top surface  416  of the fixed guide mount  402 . The fixed guide mount  402  has a chamfer  409  to ensure that the tape  108  smoothly enters the fixed guide mount assembly  400 . 
     The top surface  418  of the fixed guide  404  has two cutouts (or pad mounting surfaces)  420 ,  422 , which are located at a certain distance  424  (a range of 12.0 to 12.5 mm, with a preferred distance of 12.25 mm) from the top surface  416  of the fixed guide mount  402 . The distance  424  is smaller than the width of the tape  108 . 
     The spring/pressure pad assembly  408  comprises two pressure pads  410 ,  412  and a spring finger  419 . The pressure pads  410 ,  412  are attached to the spring finger  419  via an adhesive  426 , although any bonding procedure may be used. The pressure pads  410 ,  412  rest on cutouts  420 ,  422  and act on the top edge of the tape  108  with a certain preload (a range of 1.2 to 1.0 grams with a preferable preload of 3.2 grams). As a result, the pressure pads  410 ,  412  serve to bias the tape  108  against the top surface  416  of the fixed guide mount  402 . 
     The spring finger  419  has two fingers  428 ,  430  with different spring rates. Finger  428  has a spring rate of 200 grams/inch and finger  430  has a spring rate of 300 grams/inch. The finger  430  located nearer the magnetic read/write head  114  has a higher spring rate than the other finger  428 . As a result, the vertical position of tape  108  is corrected gently as the fingers  428 ,  430  push down on the top edge of the tape  108  forcing the tape  108  towards the top surface  416  of the fixed guide mount  402 . 
     The height  432  of the fixed guide  404  other than where the cutouts are located, is larger than the width of the tape  108 . Axial motions of the tape  108  cause the pressure pads  410 ,  412  to translate vertically. In response to this vertical translation, the pressure pads  410 ,  412  act forcibly downward on the top edge of the tape  108 . The increased height in the non-cutout areas of fixed guide  404 , which is greater than the width of tape  108 , provides support for tape  108  and ensures that the tape  108  does not buckle. 
     The cover  414  protects the pressure pads  410 ,  412  and the tape path from contamination. The cover  414  also acts as a stop to limit the vertical translation of the fingers  428 ,  430 . The cover  414 , thus, limits the spring deflection of fingers  428 ,  430  to an amount below the elastic limit or stress. If the fingers  428 ,  430  were allowed to deflect beyond this limit, then permanent deformation or “set” may result. 
     Tape  108  may be offset in the vertical direction due to manufacturing tolerances between the cartridge reel location and the fixed guide assembly  400  in fabricating tape drive  100 . Also, there is axial runout of the tape from the supply reel  106 . The dynamic runout, or tape wander, in the vertical direction is controlled very effectively by the fixed guide assembly  400  and, more specifically, by the action of the pressure pads  410 ,  412  on the top edge of tape  108 . The fixed guide assembly  404  provides support to the tape  108  across its entire width and provides pressure to the tape  108  in the zones where the pressure pads  410 ,  412  are located. 
     The forward fixed guide assembly  404  also is located precisely to provide the necessary wrap of tape  108  at read/write head assembly  114 . The location is also chosen to limit surface wear of tape  108  and to maintain the head air bearing effects. The surface of fixed guide  402  is curved, which provides a higher tape stiffness at the tape edges than the stiffness that results from a straight tape path. 
     The guide mount  400 , the fixed guide  402 , and the pressure pads  410 ,  412  are constructed from a material, such as a ceramic, such that they will not wear out during the life span of the tape drive  100 . Moreover, the material is selected such that it provides electrical conductivity to “bleed” static charges that are present in plastic films. 
     The rearweard fixed guide assembly  500 , which is shown in FIGS. 6A and 6B, is identical to the forward fixed guide assembly  400 . That is, The rearward fixed guide assembly  500  comprises a fixed guide mount  502  for mounting the rearward fixed guide assembly  500  to the main base plate  102  of the tape drive  100 . A fixed guide  504  is mounted to the fixed guide mount  502  via screws (not shown), for example. A spring  506  is mounted to the fixed guide  504  and a spring/pressure pad assembly  508  having pressure pads  510 ,  512  is mounted thereto. A cover  514  is secured to the top of the rearward fixed guide assembly  500 . 
     The top surface  516  of the fixed guide mount  502  acts as a reference surface for the tape  108 . In other words, the tape path is designed such that the bottom edge of the tape  108  travels along the top surface  516  of the fixed guide mount  502 . The fixed guide mount  502  has a chamfer  509  to ensure that the tape  108  smoothly enters the fixed guide mount assembly  500 . 
     The top surface  518  of the fixed guide  504  has two cutouts (or pad mounting surfaces)  520 ,  522 , which are located at a certain distance  524  (a range of 12.0 to 12.5 mm, with a preferred distance of 12.25 mm) from the top surface  516  of the fixed guide mount  502 . The distance  524  is smaller than the width of the tape  108 . 
     The spring/pressure pad assembly  508  comprises two pressure pads  510 ,  512  and a spring finger  519 . The pressure pads  510 ,  512  are attached to the spring finger  519  via an adhesive  526 , although any bonding procedure may be used. The pressure pads  510 ,  512  rest on cutouts  520 ,  522  and act on the top edge of the tape  108  with a certain preload (a range of 1.2 to 1.0 grams with a preferable preload of 3.2 grams). As a result, the pressure pads  510 ,  512  serve to bias the tape  108  against the top surface  516  of the fixed guide mount  502 . 
     The spring finger  519  has two fingers  528 ,  530  with different spring rates Finger  528  has a spring rate of  200  grams/inch and finger  530  has a spring rate of 300 grams/inch. The finger  528  located nearer the magnetic read/write head  114  has a higher spring rate than the other finger  530 . As a result, the vertical position of tape  108  is corrected gently as the fingers  528 ,  530  push down on the top edge of the tape  108  forcing the tape  108  towards the top surface  516  of the fixed guide mount  502 . 
     The height  532  of the fixed guide  504 , other than where the cutouts are located, is larger than the width of the tape  108 . Axial motions of the tape  108  cause the pressure pads  510 ,  512  to translate vertically. In response to this vertical translation, the pressure pads  510 ,  512  act forcibly downward on the top edge of the tape  108 . The increased height in the non-cutout areas of fixed guide  504 , which is greater than the width of tape  108 , provides support for tape  108  and ensures that the tape  108  does not buckle. 
     The cover  514  protects the pressure pads  510 ,  512  and the tape path from contamination. The cover  514  also acts as a stop to limit the vertical translation of the fingers  528 ,  530 . The cover  528 ,  530 , thus, limits the spring deflection of fingers  514  to an amount below the elastic limit or stress. If the fingers  528 ,  530  were allowed to deflect beyond this limit, then permanent deformation or “set” may result. 
     Tape  108  may be offset in the vertical direction due to manufacturing tolerances between the cartridge reel location and the fixed guide assembly  500  in fabricating tape drive  100 . Also, there is axial runout of the tape from the supply reel  106 . The dynamic runout, or tape wander, in the vertical direction is controlled very effectively by the fixed guide assembly  500  and, more specifically, by the action of the pressure pads  510 ,  512  on the top edge of tape  108 . The fixed guide assembly  504  provides support to the tape  108  across its entire width and provides pressure to the tape  108  in the zones where the pressure pads  510 ,  512  are located. 
     The rearward fixed guide assembly  504  also is located precisely to provide the necessary wrap of tape  108  at read/write head assembly  114 . The location is also chosen to limit surface wear of tape  108  and to maintain the head air bearing effects. The surface of fixed guide  502  is curved, which provides a higher tape stiffness at the tape edges than the stiffness that results from a straight tape path. 
     The guide mount  500 , the fixed guide  502 , and the pressure pads  510 ,  512  are constructed from a material, such as a ceramic, such that they will not wear out during the life span of the tape drive  100 . Moreover, the material is selected such that it provides electrical conductivity to “bleed” static charges that are present in plastic films. 
     The rearward guide roller  600 , which is shown in FIGS. 7A-7D and located near take-up reel  200 , is substantially similar to the forward guide roller  300 . As such, the rearward guide roller  600  includes a shaft  602 , which has an underside that acts a mounting surface  604  for the rearward guide roller  600 . The shaft  602  is attached to the main base plate  102  of the tape drive  100  via a screw (not shown). 
     Disposed about the shaft  602  is a rotor or sleeve  604 . The rotor  604  is supported by ball bearings  606 ,  608 , which are located at either end of the shaft  602 . A cover  610  is placed over the a distal end of the shaft  602  to prevent contaminants from falling into the interior of the rotor  604  and the ball bearings  606 ,  608 . 
     The distal end of the shaft  602  is also equipped with a slot  612  (or anti-rotation mechanism) that is used to prevent the shaft  602  from rotating during installation of the first guide roller onto the main base plate  102  of the tape drive  100 . For example, the head of a flat-head screw driver can be inserted into the slot  612  to prevent the shaft  602  from rotating while the screw (not shown) is inserted into the proximal end of the shaft  602  through the main base plate  102 . 
     When the tape is travelling at a rate greater than 1 m/sec, an air bearing is formed between the tape  108  and a conventional rotor  604 . The normal operational velocity for the tape drive  100  is about 4 m/sec. At this speed, a conventional guide roller will have little effect on tape guiding when the tape drive  100  is operated. As a result, the tape  108  flys, resulting in negligible friction loss and negligible resistance to control by the reel hub  202 . 
     After the tape  108  passes the rearward guide roller  600  it is wound on the take-up reel  200 . The quality of the winding of the tape  108  on the take-up reel  200  is maintained due to the alignment of the take up reel  200  and the design and separation of the reel flanges. 
     In the reverse read/write mode,  108  flies over the rearward guide roller assembly  600 . The pads  510  and  512  act to reduce vertical motion of tape  108  as the tape drive  100  starts and stops or switches from the reverse read/write mode to the forward read/write mode or vice versa. This ensures that tape path will be the same at the head locations in the forward and reverse read/write mode and that tape edge buckling will not occur. 
     In the tape drive according to the invention, the tension in tape is controlled by the reel that is supplying the tape, that is, the reel that is pulling the tape. If the tape drive is operating in the forward read/write mode, then the supply reel (i.e., the cartridge reel) controls the tension, but if the tape drive is operating the reverse read/write mode, then tension is controlled by the take-up reel. To ensure proper operation of the tape drive and optimal read/write performance, a certain tension (a range of 0.7 Newtons to 1.3 Newtons, with a preferable tension of 1 Newton) must be present at the read/write head. The drops in tension at the fixed guides and the guide rollers are minimal and predictable. Thus, the tension at the read/write head is very controllable with the tape path according to the invention. 
     In the inventive tape path, optimizing the size of the fixed guides, the materials used, and surface finishes, the area of tape contact is minimized. As a result, stiction is substantially avoided in high humidity environments. 
     In this disclosure there is shown and described only a preferred embodiment of the invention and but a few examples of its versatility. It is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.