Abstract:
A tape cartridge includes a first rotatable hub and a second rotatable hub. The first hub and the second hub are wound so that they are substantially full of the flexible recording tape. The flexible tape between the first and second hub crosses a centerline including the two hubs. Both the first rotatable hub and the second rotatable hub are removable from the cartridge. The hubs have a flange with a conical edge which nests into a first opening and a second opening in the tape cartridge with conical receiving surfaces. The conical edges have a plurality of reliefs therein to form conical teeth within each of the first and second hub. The conical teeth of one of the hubs engages the reliefs of the other hub to seal the cartridge and to support the tape between the hubs. The cartridge also includes a base, a latch for engaging the first rotatable hub and the second rotatable hub. A cartridge cover covers the latch and base. The tape cartridge is placed into a tape drive for reading and writing to tape media within a tape cartridge. The tape drive includes an apparatus for removing the first hub and second hub from the tape cartridge. The tape drive also includes a first spindle attached to a first arm and a second spindle attached to a second arm. The arms move the first spindle and the second spindle between a hub receiving position and a functional position. In the functional position, the first spindle and the second spindle position the tape near the transducer in a transducing relationship. Each of the spindles may include a hub flange extension or a tape packer.

Description:
FIELD OF THE INVENTION 
     The invention relates to a high performance tape cartridge. More particularly, the invention is directed toward a tape cartridge which devotes a high percentage of its volume to tape storage, and to a tape drive for this cartridge. 
     BACKGROUND OF THE INVENTION 
     Tape is a known medium or media for the storage of audio, video, and computer information. The information is typically written to and read from the tape magnetically and/or optically. Such tapes are available spooled on individual hubs and in single or dual hub tape cassettes/cartridges. The tape path for any type of tape cartridge and tape drive includes a tape head in close proximity to the tape. Many tape cartridges include an opening through which a tape head from a tape drive is inserted. The tape in a single hub tape cartridge also has an opening through which tape passes. The tape is accessed through the opening and then mechanically threaded through an external tape path and spooled onto a take-up hub after insertion into a tape drive device. The tape head has one or more transducer elements for writing to and/or reading from the tape. 
     Cassettes or cartridges including tape are commonly used to back up computer information from all types of computer systems. In work environments, tape is used to back up data or information on a regular basis. Tape and tape cartridges store vast amounts of data. In some instances, tape cartridges are used in a library which includes a tape drive coupled with a picking mechanism and a storage area for storing a number of tape cartridges. The tape cartridges in the storage area are accessible by the picking mechanism. The picking mechanism is controlled so that the picking mechanism picks a selected tape cartridge from it L F particular position in the storage area, and inserts the tape cartridge into the tape drive when the information on the particular tape cartridge is requested. The picking mechanism removes the tape cartridges from the tape drives and returns them to the storage area when the information is no longer needed. 
     When analyzing the different digital recording cartridges on the market, all have advantages and weaknesses. In general, there are two types of tape cartridges—the tape cartridge with a single hub and the tape cartridge with a double hub. The single hub cartridges have good capacities and low price, but have longer access times. In other words, it takes longer to get to the data than with a center park two hub cartridge. 
     In tape libraries, two hub cartridges with center park are preferred for their superior access time performance. Two hub cartridges which are center parked have better access time to data but have very little volume of the cartridge devoted to tape and therefore are less efficient in terms of using space. Two hub cartridges have either half the length of tape on one hub and the other half of the tape on the other hub in a two hub cartridge; or the full tape on one hub with the other hub empty; or portions of the tape of the full tape on one hub and portions of the full tape on the other hub. In this manner, the data is, at most, half the length of the tape away from its center parked position. The volume of tape compared to the volume of the cartridge is low since there are generally tape guides and other pins for providing a tape path within the cartridge. The additional pins and tape guides provide tape tracking but add to the cost of the cartridge and to the complexity of manufacture. Since each hub must have the capacity to hold the entire length of tape within the two hub cartridge on each of the hubs, tape capacity is lost since each hub is not filled with tape. In other words, each hub must have capacity in the event the entire tape is shuttled to one or the other of the hubs. The result is that a small percentage of the volume of the cartridge is tape. Generally, the volume of the cartridge devoted to tape is in the range of 7% to 10% of the total volume of the cartridge. Newer style, center park cartridges are generally costly. The many parts required add to the complexity of manufacture of the cartridges. 
     The recording capacity per cartridge is becoming increasingly important especially in tape library systems. As a result, there is a need for a two hub cartridge which can be center parked so that access to data is short. In addition, there is a need for a two hub cartridge which can hold a high volume of tape so that volumetric efficiency of the tape cartridge and the tape library which uses such a cartridge can be increased. In addition, there is a need for a cartridge which is easy to manufacture and which can be made inexpensively. 
     SUMMARY OF THE INVENTION 
     A tape cartridge includes a first rotatable hub and a second rotatable hub. A flexible recording tape is wound upon the first rotatable hub and the second rotatable hub. The first hub is wound so that it is substantially full of the flexible recording tape. The second hub is also wound so that it is substantially full of the flexible recording tape. The flexible recording tape is wound on the first hub in a first direction and wound upon the second hub in a second direction. The flexible tape between the first rotatable hub and the second rotatable hub crosses a plane including the axis of rotation of the first hub and a point on the line defining the axis of rotation of the second hub. Both the first rotatable hub and the second rotatable hub are removable from the cartridge. The hubs have a flange with a conical edge which nests into a first opening in the tape cartridge with a conical receiving surface and a second opening in the tape cartridge with a conical receiving surface. The conical edges have a plurality of reliefs therein to form conical teeth within each of the first and second hub. The conical teeth of one of the hubs engages the reliefs of the other hub. The teeth of one of the conical edges of the hubs can be unevenly spaced to lessen the distance needed to have the first and second hub engage one another. The cartridge also includes a base, a latch for engaging the first rotatable hub and the second rotatable hub. The latch is attached to the base. A cartridge cover covers the latch and base and also attaches to the base. The tape cartridge is placed into a tape drive for reading and writing to tape media within a tape cartridge. 
     The tape drive includes a transducing head for reading representations of data from the tape and for writing representations of data to the tape, and an apparatus for removing the first hub and second hub from the tape cartridge. The tape drive also includes a first spindle attached to a first arm and a second spindle attached to a second arm. A first arm moves the first spindle between a hub receiving position and a functional position. Similarly, a second arm moves the spindle between a hub receiving position and a functional position. In the functional position, the first spindle and the second spindle position the tape near the transducer in a transducing relationship. Each of the spindles may include a hub flange extension which aids in winding tape onto the first hub and the second hub. The hub flange extensions also provide capacity to the first hub and the second hub so that substantially all of the tape within the two hub tape cartridge can be placed on one of the first hub and the second hub. The tape drive may also include tape packers for each of the first hub and the second hub. The tape packers would be mounted onto a third arm and a fourth arm. The tape drive includes a mechanism for disengaging the latch on the tape cartridge. The tape drive also includes an apparatus for moving the portion of the tape cartridge other than the first hub and the second hub and the tape wound thereon, relative to the first hub and the second hub. In other words, the hubs can be dropped away from the cartridge or the cover and base can be lifted off the first hub and second hub. 
     In operation, the tape cartridge is positioned so that a first hub engages the a first spindle and so that the second hub engages a second spindle. The first and second hubs are then removed from the tape cartridge. The arms which carry the spindles are initially positioned so that the first hub and the second hub can be received. The hubs are locked onto the spindles. The first spindle and the second spindle are then moved to a second position where the tape between the first spindle and the second spindle passes over a transducing head. Hub flange extensions can be placed near the first hub and the second hub after the second or functional position is reached. A first tape packer may then be placed onto the tape pack of the first hub and a second tape packer may then be placed onto the tape pack of the second hub. 
     Advantageously, inventive two hub tape cartridge has two hubs each of which holds a full tape pack. The resulting two hub cartridge holds a higher volume of tape with respect to the volume of the tape cartridge than current two hub cartridges. The volumetric efficiency of the inventive two hub tape cartridge increases. The volumetric efficiency of a tape library which using such a cartridge also increases. The two hub cartridge can be center parked so that access to data is minimized. In addition, the inventive two hub cartridge has less parts than current two hub cartridge designs and is therefore, less expensive and easier to manufacture. The drive also mounts the hubs from the two hub cartridge onto moveable spindles. The spindles move from a load position to a functional position. As they move to the functional position, the tape is wrapped around the head and the guides of the tape drive. This load cycle is faster and more reliable than the load cycle associated with a single hub cartridge since no tape threading will be required. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following detailed description of the preferred embodiments can best be understood when read in conjunction with the following drawings, in which: 
     FIG. 1 shows a isometric view of a tape cartridge having two full tape packs. 
     FIG. 2 shows an exploded isometric view of a two hub tape cartridge with two full tape packs. 
     FIG. 3 shows a perspective view of the conical edge of one of the first and second hubs. 
     FIG. 4 shows a top view of a two full tape packs of the tape cartridge. 
     FIG. 5A shows a close-up view of the area where the two hubs of the tape drive contact one another. 
     FIG. 5B shows a close-up view of the area where the two hubs of the tape drive contact one another and where the teeth on the conical flange of one hub engage on the recesses on the conical flange of the other hub. 
     FIG. 6 shows a top view of the tape cartridge with the spindles positioning the hubs of the tape cartridge in a hub receiving position. 
     FIG.7 shows a top view of the tape cartridge and tape drive with the spindles positioning the hubs of the tape cartridge in a functional position. 
     FIG. 8 shows a tape drive which uses a belt to minimize or lessen problems associated with popped strands. 
     FIG. 9 shows a side view of the tape drive with the spindles positioned so the hubs of the tape cartridge are in a read position. 
     FIG. 10 shows a top view of a tape cartridge  900  of the prior art with all the tape within the cartridge wound onto one hub. 
     FIG. 11 shows a top view of a tape cartridge  900  of the prior art with equal amounts of the tape within the cartridge wound onto the first hub and onto the second hub. 
     FIG. 12 shows a top view of a tape cartridge  100  with the tape within the cartridge wound onto the first hub and onto the second hub. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows an isometric view of a tape cartridge  100 . The tape cartridge  100  includes a box-like housing formed by a mount plate or base  120  and a cover  140 . Cover  140  is secured to base  120  by mechanical fasteners, welding or bonding the cover  140  to the base  120 . The mechanical fasteners are typically screws. Cover  140  also includes two openings  142  and  144  which expose portions of a first tape hub  220  and a second tape hub  240  (also shown in FIG.  2 ). Unlike other tape cartridges, there is no tape access opening in the cover  140 . 
     FIG. 2 shows an exploded isometric view of a two hub tape cartridge  100 . As mentioned previously, the tape cartridge  100  includes a base  120  and a cover  140 . As shown in FIG. 2, the tape cartridge also includes a retainer or latch  210 , as well as a first hub  220  and a second hub  240 . The hubs  220  and  240  are essentially the same and have similar features and, therefore, only one hub will be described in detail. It should also be noted that the first hub  220  and the second hub  240  are shown devoid of tape in this particular view. This is so that the hubs  220  and  240  may be more clearly described. In this particular tape cartridge, as will be seen in future figures, hubs  220  and  240  each contain a substantially full tape pack while in the assembled cartridge. The base includes a pair of openings  121  and  122 , which are sized to receive the hubs  220  and  240 . The opening  121  includes a conical receiving surface  123 . The opening  122  also includes a conical receiving surface  124 . Between the openings  121  and  122  is a slot  126 . In an assembled tape cartridge  100 , the first hub  220  includes a full tape pack and the second hub  240  includes a full tape pack of magnetic tape. The first tape pack is connected to the second tape pack through the slot  126  in the base  120 . The base also includes a series of locking posts  130 ,  131 ,  132 ,  133  and  134 . Each of the locking posts includes a main body  135  and a neck  136 . The main body  135  spaces the latch or retainer  210  from the base. The retainer attaches to or is latched to the neck  136  of each of the locking posts  130 ,  131 ,  132 ,  133  and  134 . 
     The first hub  220  and the second hub  240  are substantially similar in their design, so only the first hub  220  will be described in any detail. The first hub  220  has a single flange  222 . The single flange  222  includes a beveled or conical edge  224 . The beveled edge  224  includes recesses  225  therein. The recesses  225  result in a plurality of teeth  226  which are located along the beveled or conical edge  224  of the flange  220 . The recesses  225  and teeth  226  can be equally spaced apart or can be unequally spaced apart. When unequally spaced, the pitch of the gear is varying and this allows for easier meshing of the beveled or conical edge  224  of the first hub with the beveled or conical edge of the second hub  240 . The hub  220  also includes an axle  228 . The axle  228  includes a cylindrical head  229 . The cylindrical head  229  includes a slot  230  which have substantially parallel surfaces. The slots are located between the axle  228  and the top of the head  229 . The hub  220  also includes a drum  232  which is attached to the flange and which has an outside radius which is larger than the axle. The drum  232  is substantially hollow. The inner diameter of the drum  232  is also larger than the diameter of the axle  228 . In an assembled tape cartridge  100 , a flexible tape medium is wrapped onto the drum  232  of the hub  220 . Similarly, the hub  240  has a similar drum-and-axle arrangement. 
     The retainer or latch  210  is comprised of a flat piece of material having a series of slots  211 ,  212 ,  213 ,  214  and  215  therein. The slots  211 ,  212 ,  213 ,  214  and  215  engage the necks of the locking posts  131 ,  132 ,  133 ,  134  and  130 , respectively. The retainer or latch  210  also includes two other openings  216  and  218 . The openings  216  and  218  include a central opening as well as a notch. The notch is sized such that it is able to slide within the slots  230  on the axle  228  of the hub  220  or  240 . 
     To assemble the tape cartridge  100 , the first hub  220  and the second hub  240  are positioned within the first opening  121  and the second opening  122 . The beveled conical edge  224  of each of the hubs nests within the conical receiving surfaces  123  and  124 , respectively. In other words, the beveled conical edge  224  of the flange  222  centers each of the hubs  220  and  240  within the base  120 . In an assembled position, the two hubs  220  and  240  have full tape packs and magnetic tape is wound in one direction on the first hub  220  and in the opposite direction on the second hub  240 . Tape passes through the slot  126  in the base in an assembled tape cartridge  100 . Once the first hub  220  and the second hub  240  are positioned within the base  120 , the retainer or latch  210  is positioned so that the openings  211 ,  212 ,  213 ,  214  and  215  engage the locking posts  131 ,  132 ,  133 ,  134  and  130 , respectively. In addition, the openings  216  and  218  within the retainer  210  pass over the heads  229  of the flange  222  of both the first hub  220  and the second hub  240 . 
     Both of the hubs  220 ,  240  are engaged at the same time or substantially simultaneously. This allows both of the hubs  220 ,  240  to be released at the same time or substantially simultaneously. The retainer  210  is moved in two directions to engage the hubs  220 ,  240 . This requires that the retainer  210  be moved in a first motion and a second motion to release the hubs  220 ,  240 . The two motions prevent inadvertent release of the hubs  220 ,  240  from the tape cartridge  100 . If, for example, the hubs  220 ,  240  could be released using a single motion, an inadvertent bump could replicate the motion and the hubs  220 ,  240  could be released. This would be catastrophic if the tape cartridge was in a library and a picker happened to accelerate the tape cartridge to replicate the motion. Two motions of the retainer  210  are required to lessen the chance of such an occurrence. The requirement of two motions virtually eliminates the chances of an inadvertent release of the hubs  220 ,  240 . 
     The two motions of the retainer  210  can be virtually any two motions. There can be two sliding motions of the retainer  210 ; or a rotating motion of the retainer in combination with a lifting motion of the finger  219 ; or any other combination of two motions. In the preferred embodiment shown in FIG. 2, the retainer  210  rotates and the finger  219  is lifted between a latched and unlatched position. The base  120  of the tape cartridge  100  includes a triangularly shaped strut  280 . The trianglarly shaped strut  280  includes a surface  282  over which the flat portion of the finger  219  passes when the retainer  210  rotates. One side of the trianglarly shaped strut  280  includes a step  284  which serves as a latching mechanism for the finger  219 . The step  284  in the one side of the trianglarly shaped strut  280  forms a first ledge  286  and a second ledge  288 . The finger  219  is dimensioned so that it can fit on the first ledge  286  or on the second ledge  288 . When the finger  219  is positioned on the second ledge  288  the retainer is in the second or release position where the hubs  220 ,  240  can be released from the tape cartridge  100  or put into the tape cartridge  100 . When the finger  219  is positioned on the first ledge  286 , the retainer  210  is in a second or locked position. 
     The openings  211 ,  212 ,  214 ,  215 ,  216 , and  218  are shaped so that they engage locking posts  131 ,  132 ,  134 ,  135 , and the slot  230  of the first hub  220  and the slot  230  of the second hub  240 , respectively when the retainer  210  is rotated. The opening  213  in the retainer  210  fits over the locking post  133 . The retainer  210  pivots around locking post  133 . To assemble or add two hubs  220  and  240  to the cartridge  100 , the finger  219  is positioned over ledge  286  so that the retainer  210  is in the release position. The two hubs  220 ,  240  are inserted into the openings  121  and  122  of the base  120  and the tape strand between the two hubs  220 ,  240  is passed through the slot  126 . Once positioned so that the head  229  of each of the two hubs  220 ,  240  is within the openings  216  and  218  of the retainer  210 , the finger  219  is moved from the second or release position to a locking position. In the locking position where the finger  219  is atop the ledge  286 , notches in the openings  216  and  218  engage the slots  230  in each of the hubs  220 ,  240 . The finger  219  is formed from a spring type material. As a result, the finger  219  is biased toward the ledge  286  and will not go over the step  284  unless lifted over the step. Thus, the step  284  in combination with the biased finger  219  serve as a latching mechanism to keep the retainer  210  in its locked position. 
     To release the hubs  220 ,  240  from the tape cartridge  100 , the finger  219  is moved from the first position atop ledge  286  to the second position atop ledge  288 . The second position is the release position where the notches in the openings  216  and  218  disengage from the slots  230  in each of the hubs  220 ,  240 . Once the notches in the openings  216  and  218  disengage the slots  230  in the hubs  220 ,  240 , both hubs  220 ,  240  release at about the same time. As mentioned previously, the finger  219  is formed from a spring type material so that it is biased toward the ledge  286  so that it stays in the locked or first position. To release the hubs  220 ,  240  the finger  219  is lifted over the step  284  and rotated to the release position where the finger  219  is positioned over the ledge  288 . Two motions, a lifting of the finger  219  and rotation of the retainer  210 , are thus required to release the hubs  220 ,  240  from the tape cartridge  100 . 
     Again it should be noted that to release the hubs  220 ,  240  from the tape cartridge  100 , the retainer  210  undergoes two or more motions because it is absolutely critical that the first hub  220  and the second hub  240  remain attached to the base during inadvertent shock-loading events. In other words, if the cartridge  100  should undergo a sudden motion or even any motion so that the retainer  210  moves in one direction with respect to the base, it would be catastrophic if the first hub  220  and the second hub  240  inadvertently dropped out of the cartridge. Therefore, a two motion release is used to assure or lessen the possibility of this happening. For example, if the tape cartridge  100  should be used within a tape library, the picking mechanism that is generally used, picks and moves tape cartridges quickly and, therefore, the cartridge  100  would undergo large forces which might cause the hubs to be removed inadvertently from the cartridge in the absence of a two-motion or multi-motion retainer  210  release. 
     FIG. 3 shows a perspective view of the conical edge  224  of the flange  222  of the hub  220 . As can be seen, the teeth  226  form from the beveled conical edge actually produce the bevel into which the hub  220  nests into the opening  121  or  122  of the base  120 . The recesses  225  which form the teeth, remove a portion of the flange  224 . The recessed portion is substantially perpendicular to the flange  222 . 
     FIG. 4 shows a top view of the first hub  220  and the second hub  240  as positioned within the base  120 . As shown, hub  220  contains a full tape pack  420  and the second hub  240  contains a full tape pack  440 . The full tape pack is depicted by a dotted line near the beveled conical edge  224  of the flange. The magnetic tape  400  is wound onto the first hub  220  in a counterclockwise direction or in a first direction, and wound onto the second hub  240  in a clockwise direction or in a second direction. The tape thus crosses at the point where the teeth  226  of the first hub meet or intersect with the teeth  226 ′ of the second hub  240 . It is important that the teeth  226  of the first hub  220  engage the recesses  225 ′ of the second hub  240 . When the two hubs  220  and  240  engage in this fashion, the hubs  220  and  240  become fully nested into the first conical receiving surface  123  and the second conical receiving surface  124  of the first opening  121  and the second opening  122 , respectively. When the first hub  220  becomes engaged with the second hub  240 , the flanges or the edges support the tape strand  400  that is located between the first tape pack  420  and the second tape pack  440 . This is best illustrated in FIGS. 5A and 5B which show a close-up of the area where the two hubs of the tape drive contact one another. In FIG. 5A, the teeth separate the first hub  220  from the second hub  240 . In operation, the teeth  226  of the first hub  220  are in interference with the teeth  226 ′ of the second hub  240 . The result is that the tape strand  400  between the first tape pack  420  and the second tape pack  440  is not fully supported. In addition, the cartridge  100  would not be fully sealed since there is a possibility that extraneous matter could enter the cartridge between the recesses  225  and  225 ′. FIG. 5B shows that the teeth  226  of the first hub are engaged with the recesses  225 ′ of the second hub  240 . The end result is that the tape strand  400  is fully supported and the two hubs form a sealed tape cartridge  100 . 
     FIGS. 5A and 5B also illustrate an approach for expediting the engagement of the gears or teeth from the first hub  220  and the second hub  240 . In order to expedite the meshing or engagement of the teeth of one hub into the recesses of the other hub, it is contemplated that the teeth be formed with unequal spacing so that the teeth of one hub engage the recesses of the other hub in less time than if the teeth were evenly spaced. As shown in FIG. 5A, the teeth  226 ′ are not equally spaced on the second hub  240 . Initially, one tooth  226 ′ of the second hub  240  actually interferes with one of the teeth  226  of the first hub in FIG.  5 A. The next tooth  226 ′ of the second hub  240  is positioned to engage a recess  225  of the first hub  220 . In other words, the two tape hubs  220 ,  240  after being apart in a tape drive, may initially interfere or clash. If they initially clash, they continue to clash until an unevenly spaced tooth  226 ′ engages a recess  225  as the two hubs are rotated. 
     Uneven pitch spacing of the teeth must be added for a functional quick nesting system. Since tape tension on the s-wrap must be maintained at all times, an evenly spaced tooth pattern creates an over constrained system. Uneven spacing of the teeth allows them to mesh within one revolution of the two hubs, resulting in 0.0006″ diametral uncertainty. This only works if the hubs are identical; since they turn in opposite directions they “backtrack” each other. Hubs that are mirror images of each other could conceivably clash, if presented in a mirror-perfect orientation, just as evenly spaced tooth hubs would. 
     Advantageously, the hubs with unevenly spaced teeth allow the conical flanges of two full tape hubs to overlap and to quickly nest into a hub holding device or shell. This allows the two full, removable hubs to nest properly in the shell. This also allows the tape packs on the hubs be nearly in direct contact with each other so the s-wrap (tape strand between packs) will be of a length that will clear the opening in the shell. 
     A further advantage is that the nesting occurs quickly so that the “center wind” of the drive stays within specifications. 
     If the teeth  226  and  226 ′ are evenly spaced, they will eventually mesh. The problem is that the teeth  226  and  226 ′ may mesh after the two tape pack diameter ratio is well out of spec of the center line required for the drive. If the hubs have evenly spaced teeth or two hubs with the same pitch when the two tape hubs come together after being apart in the tape drive, if the teeth initially clash, they will continue to clash as the two hubs are rotated in order to “find” a tooth mesh. The teeth will inevitably mesh, but not until after the two-tape pack diameter ratio is well out of spec of the “center wind” required for the drive, which typically is held to a few wraps of tape, or about 0.002″. The amount of rotation required is directly proportional to the number of the teeth. A 56-toothed hub would require a .04″ change in diameter to allow evenly-spaced teeth to mesh. This would require about 133 revolutions of each hub, eating up valuable drive time. The 0.04″ uncertainty directly translates to the diametral amount of tape wasted to prevent the drive from winding tape off the end of a hub in a catastrophic “dis-attach” of the tape. 
     FIG. 6 shows the top view of a tape cartridge  100  as positioned within a tape drive  600 . The tape drive  600  includes a pair of spindles  620  and  640  which engage the hubs  220  and  240 . The spindles  620  and  640  are mounted on arms  610  and  612 . Arm  610  includes spindle  620 . Arm  612  includes spindle  640 . The tape drive  600  also includes a magnetic tape head  650  as well as a first tape guide  660  and a second tape guide  662  which are positioned near the magnetic head  650 . The arms  610  and  612  are each pivotally mounted to the tape drive  600 . Arm  610  pivots about an axis  611  while arm  612  pivots about an axis  613 . As shown in FIG. 6, the arms  610  and  612  are in a first position or a hub-receiving position. The spindles  620  and  640  located on the ends of the arms  610  and  612  are positioned so that they can engage the spindles  220  and  240  in the spindle-receiving position. 
     FIG. 7 shows a top view of a tape cartridge  100  with the spindles positioning the hubs of the tape cartridge  100  in a functional position. In the functional position, the hubs  220  and  240  have been removed from the tape cartridge  100 , leaving the base  120  in one portion of the drive  600 . The spindles  620  and  640  with their attached hubs  220  and  240 , respectively, are moved into a functional position where the tape  400  is positioned over a first tape guide  660 , the magnetic head  650  and the second tape guide  662 . The arms  610  and  612  rotate about axes  611  and  613 , respectively. The tape drive  600  also includes a first pack arm  720  and a second pack arm  740 . The pack arms  720  and  740  include a roller  722  and  742  which is biased against the tape pack  420  and  440 , respectively. 
     Air can be entrapped between the layers of tape in multiple layers of the tape as it is wrapped onto a hub. The tension of the tape produces a force that attempts to push the air out from between the layers. The force is counteracted by the bleed time of the air entrapped between the layers. It generally takes a period of time for the air entrapped between the layers to flow and escape from between the layers. During the period of time while the air is flowing from between the layers of tape, the tape is floating and not in a definite position. Under normal operating conditions, this amount of time corresponds to the time it takes to wrap approximately five to six layers of tape. Whether the tape floats also depends on the roughness of the tape surface. Surface speed is also a factor in whether the tape floats. Adjacent layers fixed with respect to each other when they become pinned. The layers become pinned when the points of the surface of one tape contact the points of the surface of the other, adjacent tape. When the air film is thicker than the two combined surfaces, the tape will float and will not be stable. The tape will not become pinned until the air film between adjacent tape surfaces is thin enough to allow the two surfaces to become pinned. Popped strands are tape strands that do not lay directly over the layer of tape below the popped strand. While the tape is floating or unpinned, the tape may react to a force that causes the tape to move sideways until it is restrained by a flange on the hub or some other obstruction. When the tape does move as described above it is called a popped strand. In other words the tape pops out of place. 
     There are several ways to minimize the problem of popped strands. One way is to slow down the winding of the tape to allow sufficient time for the layers of tape to become pinned and not float. Another way of minimizing the problem of popped strands is to use rollers to force the air out from between the layers in a shorter amount of time. Rollers can be flat rollers or crowned rollers. Crowned rollers place a high force at a point on the wound tape. Flat rollers place a force along a line across the tape. The rollers iron out the air causing the tape to pin and prevent the adjacent layers of tape from floating. 
     Pack arms  720  and  740  carry the rollers and add a force to the squeeze iron out any air that might be trapped between layers of tape as the tape is wound onto the hub  220  or  240 . The pack arms prevent or lessen popped strands by forcing the air film between layers more quickly. In other words, the pack arms  720  and  740  and their associated rollers force the air film out faster which causes adjacent layers of tape to become pinned more quickly. The minimization or elimination of popped strands is desirable. Popped strands cause edge wear on the tape. Popped strands also cause tracking errors since the tape can move from side to side with respect to the surface of the flange and with respect to the magnetic head. 
     Another advantageous feature of this drive is that the spindle  620  and the spindle  640  can be moved to reduce the angle over the tape head when tapes travel over the magnetic head  650  at high speeds. In FIG. 7, the arms  610  and  612  and associated spindles  620  and  640  are in a functional position that may be associated with a relatively low speed travel for the tape  400  over the magnetic head  650 . In the event that the tape  400  is required to pass over the guide  660 , the head  650  and the other guide  662  at a faster speed, the arms  610  and  612  can be rotated toward the tape cartridge or base  120  that remains in the drive to reduce the angle and reduce the wear on the tape. By reducing the angle with respect to the guides  660  and  662 , as well as with respect to the head  650 , wear is reduced on the tape  400 . 
     As shown in FIG. 8, rather than having tape pack arms  720  and  740 , a belt system  800  can be substituted for the pack arms  720  and  740 . 
     The belt/system  800  includes a first pulley  801 , a second pulley  802 , and a third pulley  803 . A belt  805  passes over the first pulley  801 , the second pulley  802  and the third pulley  803 . The belt contacts the tape pack  440  on the second hub  240  and forces or squeezes any air that might be trapped between the layers of the tape as the tape is wound onto the hub  240 . The belt  805  is also in contact with the smaller tape pack  420  of the hub  220 . By having the belt  805  in contact with the tape pack  440 , air entrapped between the layers of tape is forced out so that popped strands or tape movement between the various layers is minimized. As shown, the hub  801  is turning in one direction while the tape is being wound onto the spindle  240 . The spindle  501  is turned in the opposite direction thereby moving the belt  805  in the opposite direction when the tape is being wound onto the spindle  220 . The tension on the tape  805  is maintained so that air may be removed or squeezed out from between the layers in the tape pack. Therefore, the tape is pinned to bottom layers and popped strands are minimized. 
     FIG. 9 illustrates a set of flange extensions  820  and  840  which are associated with the hub  220  and hub  240 . The hub extension  820  engages the teeth  224  and  226  of hub  220  and the teeth  226 ′ the hub  240 . A second flange  822  for hub  220  is positioned within the tape drive. The second flange is mounted so that it can be brought down into contact with the hub  220 . The outer edges or outer circumference of the second flange  822  and the flange extension  820  bound the tape that is wound on the hub  220 . The flange extension  820  and the flange  822  prevent the tape from moving laterally and therefore minimize popped strands. Similarly, associated with hub  240  is a second flange  842  which is located within the tape drive and which can be moved into place adjacent the hub  240 . The flange of the second portion  842  and the flange extension  840  bound the tape as it is wound onto the hub  240 . 
     In operation, tape packs must be removed from the tape cartridge  100  since there is no room in the container to shuttle tape from one hub  220  to a second hub  240 . The flexible recording tape on the first rotatable hub and on the second rotatable hub hold information representing data. The data is accessible only when the first hub and the second hub are removed from the tape cartridge  100 . The first rotatable hub and the second rotatable hub are inoperable unless removed from the cartridge since tape can not be shuttled from the first hub  220  to the second hub  240 , or vice versa. Of course, the first rotatable hub  220  and the second rotatable hub  240  are replaceable with respect to the tape cartridge  100 . 
     The drive spindles are mounted on the arms  610  and  612  so they can move from a hub-receiving position to a functional position. The hub-receiving position is shown in FIG.  6  and the functional position is shown in FIG.  7 . This cycle is required to load the tape  400  into the tape drive  600 . Initially, the cartridge  100  is lowered onto the spindles  620  and  640 , attached to the ends of the arms  610  and  612 , respectively. The hub  220  is latched to the spindle  620 . The hub  240  is latched to the spindle  640 . Once the spindles are latched to the hubs  220  and  240 , the cartridge latch or retainer  210  is released by moving the retainer in a first direction and a second direction. The retainer  210  is moved by placing a force on the tab  219  of the latch or retainer  210 . Once accomplished, either the spindle arms  610  and  612  are lowered, or the empty container or empty cartridge  100  is raised. The arms  610  and  612  are then rotated into their functional position, as shown in FIG.  7  and the tape  400  is passed over a first guide bearing  660 , a second guide bearing  662  and the magnetic head  650 , all of which are positioned within the tape drive  600 . The last movement allows the tape  400  to be wrapped around the magnetic head  650  and the guides  660  and  662  of the tape drive  600 . The load cycle takes approximately 1 to 3 seconds. Advantageously, this load cycle is faster and more reliable than the cycles required to load a single real cartridge onto the drive. The reason for the increased speed and reliability is that there is no tape threading required. 
     Advantageously, the long tape span helps with guiding and tracking. In addition, the arms  610  and  612  can be rotated to different angles depending upon the speed at which the tape is being passed over the guides  660  and  662 , as well as the magnetic head  650 , so as to prevent excessive wear on the tape  400 . In the functional position, where the tape  400  can be read from or written to pack arms  720  and  740 , a belt  800  or flange extensions  820  and  840  (not shown as yet in the figure), may be used to control tape pack formation. In other words, the flange extensions  820  and  840 , or pack arms  720  and  740 , can be used to efficiently pack the tape and form good tape packs  420  and  440 . Use of pack arms  720  and  740  allow for very fast tape movement without “popped strands”, thus improving tape tracking. With this approach, up to 31% of the tape cartridge  100  could be devoted to tape. The same shape could be maintained with respect to other cartridges. Other shaped cartridges could have a high percentage of volume of tape, approximately in the range of 40-50%. The additional volume comes from having two substantially full hubs  220  and  240  (illustrated in FIG. 11 below). In addition, a wider tape can be used since there is no need for a second flange on each hub and the clearance necessary for the second flange. There is also no need clearance for the flanges on the hubs  220  and  240  since these hubs do not rotate within the cartridge. The tape cartridge  100  can also be more ruggedly built with thicker walls and no need for door mechanisms that open to allow access to the tape within the tape cartridge  100 . The mechanical structure is more rugged and robust and easier to build. Furthermore, with two full tape hubs, the tape cartridge is better able to withstand shock loading. Thus, an additional advantage is that the two hub tape cartridge could become much more volumetrically efficient. In other words, today&#39;s tape drives devote less than 10% of their total volume to holding tape. The tape drive described herein could carry anywhere from 30-50% of the volume devoted to tape. The volume devoted to tape in the tape cartridge  100  could also range somewhere from 10-65% of the total volume of the tape cartridge. 
     FIGS. 10 and 11 show a tape cartridge  900  of the prior art. In prior art cartridges  900 , the hubs  920 ,  940  must be able to rotate. As shown in FIG. 10, the amount of tape  910  held in the prior art cartridges is limited by the amount that is held on one hub  920  or  940  since the tape may need to be wound on one of the hubs to access data on one or the other ends of the tape. As shown on FIG. 11, an equal amount of the tape is wrapped onto each of the hubs  920  and  940 . The hubs  920  and  940  can not be full since they are designed to rotate. In 
     In contrast, as shown in FIG. 12, each of the hubs  220  and  240  are entirely full. This accounts for much of the increase in the volumetric efficiency of the tape cartridge  100  of this invention. Other factors are discussed above. Still another factor is that the tape cartridge  100  does not need tape guides and other mechanisms for routing the tape through the tape cartridge  100 . 
     Advantageously, inventive two hub tape cartridge has two hubs each of which holds a full tape pack. The resulting two hub cartridge holds a higher volume of tape with respect to the volume of the tape cartridge than current two hub cartridges. The volumetric efficiency of the inventive two hub tape cartridge is increases as is the volumetric efficiency of a tape library which uses such a cartridge. The two hub cartridge can be center parked so that access to data is minimized. In addition, the inventive two hub cartridge has less parts than current two hub cartridge designs and is therefore, less expensive and easier to manufacture. The drive also mounts the hubs from the two hub cartridge onto moveable spindles. The spindles move from a load position or hub removal position to a functional position. As they move to the functional position, the tape is wrapped around the head and the guides of the tape drive. This load cycle is faster and more reliable than the load cycle associated with a single hub cartridge since no tape threading will be required.