Patent Document

RELATED APPLICATION 
     The present application claims priority from prior U.S. Provisional Patent Application Ser. No. 60/250,188 filed Nov. 29, 2000 which is fully incorporated herein by reference. This application relates to application Ser. No. 09/774,356, filed Jan. 30, 2001, and application Ser. No. 09/774,380, filed Jan. 30, 2001. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a tape system that can include a tape drive and a tape cartridge for housing data storage tape and, in particular, to a tape drive that includes a control mechanism for attaching/detaching at least one leader band to/from the data storage tape. 
     BACKGROUND OF THE INVENTION 
     Tape drives having a single tape reel use removable tape cartridges for obtaining the tape upon which and from which such tape drives write/read data. In particular, each of the tape cartridges used by such a tape drive has a complementary tape reel therein upon which the tape resides when not being operatively used in conjunction with the tape drive. In order to protect the tape and the data thereon from damage, the tape within each cartridge is not intended to be accessible except by the tape drive. Accordingly, the tape drive must include a mechanism for automatically threading the tape through the tape drive between the tape cartridge and the single reel of the tape drive. Various techniques have been used to perform such automatic threading. In connection with designing such tape drives, certain technical challenges have been identified that are commonly addressed, namely: 
     (a) The mechanism for pulling the tape through the tape drive is frequently unreliable in that, e.g., the tape drive threading components used for engaging with the free end of the tape during the threading of the tape by the tape drive do not engage reliably. Similarly, the tape drive components may also fail to disengage from the tape during the unthreading of the tape from the tape drive. Thus, the tape drive may fail to access the tape in some cartridges and/or a tape cartridge may become stuck within the tape drive. 
     (b) Once the free end of the tape has been secured for threading to, e.g., what is known in the art as a “leader band” (or simply “leader”), the tape free end may inadvertently disengage from the leader band during threading and/or become misaligned and fail to fully thread thus potentially damaging the tape drive. 
     (c) Due to the flexibility and thinness of many tapes currently used for data storage, the free end of the tape itself is not typically grasped (ungrasped) during threading (unthreading) operations. Instead, an appendage is provided on the free end of the tape, wherein this appendage is more readily grasped (ungrasped). Such an appendage may include a substantially rigid cylindrical, semicircular or other shaped component having a thickness substantially greater than the thickness of the tape. Alternatively, the appendage may include a slot for mating with an end portion of the leader band. In all such cases, the resulting coupling of the tape free end and the leader band is substantially thicker than the tape itself. Thus, when this substantially thicker coupling portion winds about the single reel of the tape drive, a non-smooth surface results which can compromise the data encoded on the tape that is subsequently wound on top of the non-smooth surface. 
     Although solutions to these technical issues have been advanced, it remains desirable to provide a tape drive that overcomes or alleviates them in an efficient manner. Such solutions should avoid complex mechanical configurations, be cost effective and reliable. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a tape system is provided that includes a take up assembly for winding/unwinding magnetic or other data storage tape. The tape system also includes a leader assembly to which the data storage tape is releasably joined. The tape system further includes a load/unload control mechanism that functions to attach/detach the leader assembly to/from the tape. 
     The load/unload control mechanism engages at least portions of the leader assembly to cause desired movement thereof in conjunction with tape loading/unloading relative to the removably held tape cartridge. In that regard, the control mechanism is used in moving the leader assembly in at least two directions when loading or joining the leader assembly to the storage tape. In one embodiment, the control mechanism causes the portions of the leader assembly to move in a first direction that is generally a straight movement from the tape drive to the tape cartridge. And, a pivotal movement is then caused to occur, preferably in a clockwise direction, for positioning the leader assembly to engage the storage tape. More specifically, the storage tape has a pin held adjacent to its free end. The leader assembly includes at least a first leader band and a connector subassembly. In one embodiment, the leader assembly has first and second leader bands. The connector subassembly can include a pair of hooks interconnected by a hook stay. In this embodiment, when loading the data storage tape, the control mechanism causes upper portions of at least the first leader band and the hook subassembly to move into the tape cartridge and then pivot clockwise. When necessary or desired, the hook subassembly and the upper portions of the at least first leader band are then moved in a substantially straight direction towards the exit of the tape cartridge. In so doing, the hooks engage the tape pin and remove it from its seat as the hook subassembly and the upper portions of the first leader band move to exit the tape cartridge. 
     Comparable opposite directional movements are caused to occur when the storage tape is detached from the leader assembly (unloading operation). In particular, the leader assembly holding the tape pin moves into the tape cartridge and continues in a generally linear direction. During this movement, the tape pin seat for holding the tape pin in the tape cartridge is encountered. After the tape pin seat receives the tape pin, the hook subassembly and upper portions of the first leader band are caused to move in a counterclockwise direction. Alternatively, if desired or appropriate, after release of the tape pin in the tape pin seat, the leader assembly may continue for a short distance in the generally straight direction and then pivot counterclockwise. After the counterclockwise movement, the leader assembly is caused to move without the tape pin in the opposite generally linear direction towards and out of the tape cartridge. 
     The control mechanism for causing such loading/unloading movements can include a number of gears. These gears might include a drive gear, which is attached to a shaft of a motor. The gears can also include a planetary gear that meshes with the drive gear. A sprocket gear can also be provided to rotate one or more sprockets. Such a sprocket will engage holes in the first leader band, for example. A cam gear may also be utilized for use in rotating a cam. The cam movement is useful in causing the pivoting movement of the hook subassembly. 
     The planetary gear is selectively meshable with either the sprocket gear or the cam gear. When moving the leader assembly in the generally linear directions, the planetary gear meshes with the sprocket gear, and not the cam gear, so that when the planetary gear is driven, the sprocket gear causes the one or more sprockets to move the leader assembly in the generally linear directions. When a planetary gear meshes with the cam gear, and not the sprocket gear, the cam is caused to rotate to achieve the selected rotational or pivotal movement. 
     With regard to achieving the selective engagements between the planetary gear and the sprocket gear and between the planetary gear and the cam gear, the control mechanism can include a pivotal arm. When the motor is driven clockwise, the pivotal arm rotates clockwise. When the motor is driven counterclockwise, the arm rotates counterclockwise. When the arm rotates clockwise, it disengages the planetary gear from the sprocket gear and engages with the cam gear. When the arm rotates counterclockwise, the planetary gear is disengaged from the cam bear and engaged with the sprocket gear. 
     The control mechanism preferably also includes a biasing device, such as a spring. The spring is operably connected to other portions of the control mechanism. The spring is preferably biased to allow or enable at least portions of the control mechanism to pivot in a counterclockwise direction. Consequently, when the leader assembly is caused to pivot in the clockwise direction, the force of the spring must be overcome during such pivotal movement. 
     Although the control mechanism can be used with any number of different configurations, in a preferred embodiment, the take up assembly includes a take up reel hub having at least a first take up reel connected to and spaced from the take up reel hub. In an even more preferred embodiment, first and second take up reels are provided, with the take up reel hub located intermediate thereof. The take up reel hub has a circumferential surface about which the magnetic tape winds and unwinds. Each of the one or both take up reels has a leader band wound thereabout. Because of the spaced, separate take up reel or reels, there is no overlap or contact between the leader bands and the magnetic tape. 
     Based on the foregoing summary, a number of advantages of the present invention are readily discerned. A reliable tape loading/unloading control mechanism is provided. The control mechanism causes different movements in order to enter the tape cartridge and either access or release a tape pin. A reduced number and efficient use of parts are achieved in the control mechanism design. In that regard, a unique arrangement and operation of a number of driven gears and a cam are provided. The control mechanism controls desired movement of both an elongated storage tape and a connector subassembly, in the form of a pair of hooks, into and out of a tape cartridge. In one embodiment, the leader assembly with which the control mechanism functions has first and second leader bands spaced from but connected to each other using the hook subassembly. In another or the same embodiment, the take up assembly has separate parts for winding/unwinding the storage tape and winding/unwinding one or more leader bands. 
     Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 schematically illustrates a tape cartridge removably held by a tape drive that includes a control mechanism for positioning a leader assembly adjacent to a leader pin; 
     FIG. 2 is a perspective view illustrating assemblies and parts of the tape drive; 
     FIG. 3 is a schematic view of a tractor assembly for use in moving the leader assembly; 
     FIG. 4 is an enlarged, perspective view of the leader pin, with a pair of hooks of a connector subassembly positioned for engagement with the leader pin; 
     FIG. 5 is an enlarged, fragmentary, perspective view of the leader assembly including first and second leader bands and the connector subassembly; 
     FIG. 6 is an enlarged, fragmentary side view of one of the two hooks of the connector subassembly, with the leader pin being illustrated as about to be joined with a hook; 
     FIG. 7 is a diagrammatic view of the control mechanism including the plurality of gears involved in controlling movement of the leader assembly; 
     FIGS. 8A-8F diagrammatically illustrate sequential steps that are conducted related to loading (attaching) of the leader assembly to the leader pin; 
     FIGS. 9A-9E diagrammatically illustrate sequential steps that are conducted related to unloading (detaching) the leader assembly from the leader pin; 
     FIG. 10 diagrammatically illustrates a tape drive and tape cartridge, with a take up assembly including a take up reel hub and take up reels; 
     FIG. 11 is an enlarged, perspective view of the take up assembly; 
     FIG. 12 is an exploded view of the take up reel hub including a first embodiment of a door mechanism; 
     FIG. 13 is a perspective view of the take up assembly illustrating the take up reel hub, the take up reels and the two pairs of flanges on the opposing sides of the take up reel hub; 
     FIG. 14 is a diagrammatic illustration of data storage tape being wrapped about the take up reel hub; 
     FIG. 15 diagrammatically illustrates the leader pin located relative to the take up reel hub; 
     FIG. 16 is a perspective view of a take up assembly illustrating a second embodiment of a door mechanism; 
     FIG. 17 illustrates the door mechanism of the second embodiment in its closed position; 
     FIG. 18 diagrammatically illustrates the door mechanism of the second embodiment in its open position, with the take up assembly wrapping portions of the leader assembly; and 
     FIGS. 19A-19G diagrammatically illustrate a sequence of steps in which the door mechanism of the second embodiment changes from its open position to its closed position as the door mechanism contacts the leader pin joined to the data storage tape. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows an embodiment of the present invention in the context of a single reel magnetic tape drive  20 . In particular, FIG. 1 shows the tape drive  20  with a tape cartridge  24  positioned within the tape drive wherein magnetic or other data storage tape  28  is wound around the cartridge hub  32 . However, during operation, the magnetic tape  24  is automatically threaded through the tape drive  20 , over the read/write head  38  (for reading from and/or writing to the tape) and subsequently wound on the take up assembly  40 , and more particularly, wound around the take up reel hub  42 . 
     To provide a better appreciation as to the relationship between various components of the present invention and the tape cartridge  24 , reference is made to FIG. 2 wherein a partially exploded view of a tape drive assembly  44  is provided having both the tape drive  20  and the tape cartridge  24  therein. Moreover, this figure shows the tape cartridge  24  operably positioned adjacent to the tape drive  20  for reading and/or writing of the tape  28 . Note that the tape drive assembly  44  includes a front panel  48  with a door  52  covering an opening for entry and exit of the tape cartridge  24  from the tape drive assembly  44 . Thus, the tape drive assembly  44  is designed to accept tape cartridges  24  having a configuration and orientation substantially as shown in FIGS. 1 and 2 during operation of the tape drive  20 . 
     Referring to the tape cartridge  24  in somewhat more detail, it includes a substantially cylindrical leader or tape pin  56  (FIGS. 1 and 4) attached to an end of the tape  28  such that when the tape  28  is fully retracted into the tape cartridge  24  (and thus wound about the cartridge hub  32 ), the leader or tape pin  56  seats within the pin recess  59  of the tape cartridge. The leader pin  56  has five sections; they are: (i) a central cylindrical body  58 , (ii) two pin slots  60 , one at each end of the cylindrical body wherein each pin slot includes a reduced diameter cylindrical slot interior  62  and two opposing sides  64 ; and (iii) two cylindrical end pieces  66 , one at each end of the leader pin. The pin recess  59  includes two spaced apart pin stays  65  that are positioned so that the leader pin  56  seats against these stays  65  when resting within the recess  59 . In particular, each end piece  66  seats with an adjacent pin stay  65  so that the pin slots  60  are not occluded by the pin stays  65  and therefore remain fully accessible from the interior of the tape cartridge  24 . That is, the pin stays  65  do not restrict access to the reduced diameter cylindrical slot interiors  62 . 
     Returning now to FIG. 1, note that a threader band  80  (also denoted a leader) is provided within the tape drive  20  for threading the tape  28  through the tape drive  20 . In particular, the leader  80  is threaded along the leader path  82  which is, in one embodiment, two parallel spaced apart slots  84  provided within a threading frame  88  (FIGS.  1  and  3 ). Accordingly, the leader  80  is attached at one end to the take up reel assembly  40  while the other end of the leader has a hook  94  attached thereto for hooking the leader pin  56  for threading the tape  28  through the tape drive along a similar (but not identical) path as the leader path  82  taken by the leader  80 . Thus, once the pin  56  is secured by the hook  94 , the take up reel assembly  40  rotates thereby winding the leader  80  on the take up reel assembly  40  and consequently threading the magnetic tape through the tape drive  20 . 
     A more detailed illustration of an embodiment of the hook end of the leader  80  is shown in FIG.  5 . In particular, note that the leader  80  has two spaced apart parallel threading bands  98  that are only connected to one another via their attachments at one end to the take up reel assembly  40 , and via the connector, e.g. hook subassembly  94 , at the opposite end of the threading bands. The threading bands  98  are spaced apart a distance appropriate for freely moving in the parallel slots  84  (FIG. 3) in the direction of the leader path  82 . Moreover, note that such spacing between the threading bands  98  is greater than the width of the magnetic tape  28 ; e.g., for a magnetic tape having a width of about 12.65 mm, the threading bands  98  may be spaced apart by about 17 mm. Each threading band  98  includes a series of equally spaced holes  102  spaced along the end of the threading band  98  adjacent to where the hook subassembly  94  attaches thereto. These holes  102  are for engaging the teeth of a sprocket and thereby assuring that the hook end of the leader  80  moves in a desired manner during the hooking and unhooking of the leader pin  56  (as will be further described hereinbelow). Additionally, at least one of the threading bands  98  includes sensor holes  106  for allowing light from light-emitting sensors within the tape drive  20  to pass through the threading band for detection by corresponding light-receiving sensor along the leader path  82  as will also be described further hereinbelow. 
     Regarding the hook subassembly  94 , included therein are two pin hooks  110  with a stay  114  fixedly attached therebetween. Each of the pin hooks  110  has one end attached to a threading band  98 . From this attachment each pin hook  110  extends in a particularly advantageous hook shape for reliably hooking and unhooking the leader pin  56 . In particular, each of the pin hooks  110  is curved for entering into a corresponding one of the pin slots  60  so that the slot interior  62  of the pin slot is captured within the interior of the pin hook in a manner that substantially precludes accidental dislodgement therefrom during threading or unthreading of the magnetic tape from the tape drive  20 . 
     FIG. 6 shows a view of one of the pin hooks  110  thereby illustrating the novel shape of the pin hook. However, in order to more fully appreciate the functional aspects of the pin hook  110 , a brief description of the hooking action is now provided. Accordingly, for hooking the slot interiors  62  of the leader pin  56 , each pin hook  110  enters the tape cartridge  24  through the opening  68  wherein each pin hook  110  is adjacent to one of the pin slots  60 . Subsequently, the pin hooks  110  are synchronously pivoted clockwise (in a manner further described hereinbelow) so that the hook opening  118  of each pin hook  110  rotates into alignment with the adjacent slot interior  62 . Thus, as the leader  80  retracts from the tape cartridge  24 , each slot interior  62  enters the adjacent hook opening  118  and subsequently traverses the hook interior along the direction of arrow  122  until the slot interior contacts the closed end  126  of the pin hook. 
     Note that the unhooking action is substantially the reverse of the hooking action. That is, the hooked leader pin  56  seats in the pin recess  59 , the hook pins  110  disengage from the slot interiors  62  by entering the tape cartridge  24 , the hook subassembly  94  is rotated counterclockwise so that when it is retracted from the tape cartridge  24 , the pin hooks  110  can retract from the tape cartridge without re-engaging the slot interiors  62 , and additionally, without re-engaging the leader pin  56 . 
     Accordingly, given the above hooking and unhooking description, the novel curvature of the pin hooks  110  may now be appreciated. In particular, note that the hook opening  118  is angled from the plane or width of the leader  98  (FIG. 6) at about 30° (more generally, in a range of 10° to 45°), and the hook opening  118  has a width (at arrow  130 ) that is somewhat wider than the diameter D of the slot interior  76  (e.g., the width being about 1.7 mm for D being about 1.6 mm). Thus, when the hook  94  rotates clockwise and is retracted from the tape cartridge  24 , the pin hooks  110  easily grasp the slot interiors  62 . Subsequently, upon further retraction of the hook subassembly  94  out of the tape cartridge  24 , each slot interior  62  slides along the path indicated by the arrow  122  of the hook interior  124  and seats at the closed end  126  of the pin hook. Thus, since the pin hook interior width (e.g., at the arrows  132 ) is only marginally wider than the diameter D of the slot interior  62 , and since the thickness  134  (FIG. 5) of each pin hook is only marginally smaller than the distance between the parallel sides  64  of a pin slot  60 , each pin hook snugly engages the leader pin  56  such that there is substantially no lateral leader pin movement transverse to a direction it travels along the leader path  82 . Moreover, since the pin hook interior is angled relative to the directions (e.g., arrows  134  and  138 ) of hook subassembly  94  movement during the tape threading and/or unthreading processes, the leader pin  56  is not susceptible to disengagement from the pin hooks  110  in the directions of arrows  134  and  138 . In particular, when the engaged leader pin and hook subassembly  94  are rapidly slowed down during the threading and/or unthreading process, any potential movement for decoupling the pin  56  and the hook subassembly  94  is substantially precluded since such movement is likely to be in the directions of arrows  134  and  138  and not in the angled direction that the leader pin would have to travel in order to exit from one or both of the pin hooks  110 . Thus, the pin  56  and the hook subassembly  94  remain reliably engaged during the threading and unthreading operations of the tape drive  20 . 
     As described hereinabove, during hooking and unhooking of the pin  56  by the hook subassembly  94 , the hook subassembly is rotated clockwise and counterclockwise respectively. The hook pivot assembly  160  (e.g., FIGS.  1 , 7 ,  8 A- 8 E) performs this task. Referring to FIGS. 1 and 7, the hook pivot assembly  160  is pivotable as a unit about pivots  164  (shown in FIG. 7 as separate components of the tape drive  20  that attach the hook pivot assembly  160  to the remainder of the tape drive  20 ; however, various arrangements of pivots  164  are within the scope of the invention including pivots that are integral with, e.g., the upper and lower threading tracks  176   a  and  b  described hereinbelow). The hook pivot assembly  160  is also biased to pivot in a counterclockwise direction by the spring  168  (FIG. 1) wherein the spring attaches at one end to the pivot assembly  160  and the other end to the threading frame  88 . As can be best seen in FIG. 6, the pivot assembly  160  includes an end portion of the leader path  82  which includes the upper and lower threading tracks  176   c  and  d  that provide paths for the threading bands  98  along the leader path  82  through the hook pivot assembly  160 . Note that each of the threading tracks  176   a-d  has a ledge  180  that functions as a guide for the threading bands  98 . Moreover, note that each of the threading tracks  176   a-d  is at least partially provided in a corresponding recess  184  that also serves as a threading band guide along the leader path  82 . 
     The hook pivot assembly  160  also includes a motor  188  for driving a plurality of gears that cause the hook pivot assembly  160  to pivot, and also cause the hook  94  subassembly to move into and out of the tape cartridge  24  in the direction of the leader path  82  adjacent to the magnetic tape exit from the tape cartridge  24 . Note that there are four gears included in the hook pivot assembly  160 , these being: 
     (i) A drive gear  192  which is attached to the shaft  186  of the motor  188 , wherein the drive gear is directly driven by the motor; 
     (ii) A planetary gear  196  which is driven by the drive gear  192 ; 
     (iii) A sprocket gear  200  which is intermittently driven by the planetary gear  196 , wherein the sprocket gear, in turn, is attached to and rotates a pair of sprockets  204  (only one of which is shown in FIG. 7) for moving the leader  80  along the leader path  82  (as will be further described hereinbelow); and 
     (iv) A cam gear  208  which is also intermittently driven by the planetary gear  196 , wherein the cam gear, in turn, is attached to and rotates a cam  212  for pivoting the hook pivot assembly  160  (as will also be further described hereinbelow). 
     Additionally, note that the planetary gear  196  is attached to the remainder of the hook pivot assembly  160  by an arm  216  (FIGS. 1,  8 , and  9 ) that pivots about the shaft  186 . In particular, the planetary gear  196  is rotatably attached to the end of the arm  216  opposite the arm attachment to the shaft  186 . Thus, the arm  216  is able to pivot the planetary gear  196  between at least a first position for engaging the teeth of the sprocket gear  200 , and a second position for engaging the teeth of the cam gear  208 . 
     Referring now primarily to FIGS. 8A-8F, the operation of the pivot assembly  160  during the attaching of the hook  94  to the leader pin  56  is shown. Accordingly, in FIG. 8A, the pivot assembly  160  is in an inactive state, wherein the leader  80  extends along the leader path  82  from the take up reel assembly  40  to the open end  220  of the leader path. Moreover, at least one hole  102  of each threading band  98 , nearest the hook  94 , is grasped by the pair of sprockets  204  thereby securely holding each threading band  98  in its corresponding threading track  176 . 
     Upon receiving a request for threading a tape through the tape drive  20 , an electronic controller (not shown) therein activates the motor  188  to rotate counterclockwise as shown in FIG.  8 B. Accordingly, the drive gear  192  causes the planetary gear  196  to rotate clockwise. Moreover, substantially concurrently with the activation of the motor  188 , the arm  216  pivots counterclockwise so that the teeth of the planetary gear  196  meshes with the teeth of the sprocket gear  200 . Thus, the counterclockwise rotation of the drive gear  192  induces a counterclockwise rotation of the sprockets  204 . Moreover, since the spacing of the holes  102  match the spacing between the teeth of each of the sprockets  204 , the sprocket teeth mate with the holes  102  to thereby urge the hook  94  to extend out of the open end  220  of the pivot assembly, and into the tape cartridge  24  as shown in FIG.  8 C. In particular, note that the hook  94  extends further into the tape cartridge  24  than where the pin  56  is seated against the pin stays  64 . Additionally, once the motor  188  stops and the hook subassembly  94  is maximally extended into the tape cartridge  24  (such maximal extension being, e.g., approximately 8 mm of the leader  80 ), the motor  188  is driven clockwise and the arm  216  rotates clockwise so as to disengage the planetary gear  196  from the sprocket gear  200  and engage with the cam gear  208 . Following this, the motor  188  is driven to rotate in the opposite (e.g., clockwise) direction as shown in FIG.  8 D. Thus, there is a resulting clockwise rotation of the cam gear  208  which causes the cam  212  to correspondingly rotate and thereby bias the pivot assembly  160  away from the threading frame  88  in a clockwise pivoting action about the pivots  164 . Moreover, the motor  188  rotates the cam gear  208  until a sensor interrupt flange  224  (FIG.  7 ), that is attached to the upper cam surface  228 , rotates into a position wherein this flange interrupts a light beam emitted from a light-emitting sensor (not shown, but in one embodiment, residing adjacent the motor surface  228  of FIG. 7; however, the sensor is mounted to the threading frame  88 ). In particular, the light beam emitted by the light-emitting sensor is directed in the direction of a light-receiving sensor, wherein this light-receiving sensor is operatively connected to the controller for thereby deactivating the motor  188  when light is no longer sensed. Note that as shown in FIG. 8E, such deactivation takes place when the cam  212  is in a position for substantially maximally pivotally biasing the pivot assembly  160  clockwise away from the threading frame  88 . Thus, the pivoting action induces the hook subassembly  94  to move toward the pin  56  such that the pin is between the hook opening  118  and the threading track  176 . Thus, with the pivot assembly  160  remaining in the clockwise pivoted position, the arm  216  is again pivoted about the shaft  186  in a counterclockwise direction so that the planetary gear  196  disengages from the cam gear  208  and engages the sprocket gear  200 . Consequently, the electronic controller activates both the motor  188  to rotate the drive gear  196  in the clockwise direction, and a motor (not shown) of the take up reel assembly  40  for winding the leader  80  thereabout. Thus, the sprocket gear  200  and the sprockets  204  also rotate in a clockwise direction thereby causing the hook subassembly  94  to engage the pin  56 , and more particularly, cause each of the pin slots  60  to enter a corresponding hook interior  124  and seat against the corresponding pin hook closed end  126 . Subsequently, as the sprockets  204  continue to pull the leader  80  along the leader path  82  (and the opposite end of the leader is correspondingly wound about the take up reel assembly  40 ), the pin  56  and the attached magnetic tape  28  are threaded through the tape drive  20 . Note that it is an aspect of the present invention that the leader  80  (and more particularly the threading bands  98 ) preferably be somewhat stiff, albeit flexible enough to wind about the take up assembly  40 . In particular, such stiffness facilitates accurate movement and positioning of the hook subassembly  94  during the grasping and ungrasping of the pin  56 . In one embodiment of the present invention, a leader stiffness of approximately 50 Newtons per square millimeter has been found effective for reliably hooking and unhooking the pin  56 , plus, retaining sufficient flexibility to properly wind the leader about the take up reel hub  42 . However, it is believed that a leader stiffness in the range of 50 to 70 Newtons per mm 2  may be used in various embodiments of the present invention. 
     Note that once the hook subassembly  94  passes the sprockets  204 , detection by a sensor provides the electronic controller with an input that causes it to instruct the motor  188  to deactivate. Thus, the pivot assembly  160  remains in the fully pivoted position until, e.g., the tape  28  is rewound about the cartridge hub  32 , and the pin  56  and hook subassembly  94  are decoupled. Also, note that once the hook subassembly  94  passes the sprocket  204  during the threading process, the leader  80  and the tape  28  continue to be threaded through the tape drive  20  by the winding of the leader about take up assembly  40 . FIG. 10 shows a configuration of the tape drive  20 , wherein the leader  80  has threaded the data storage tape  28  through an initial portion of the tape path through the tape drive. In particular, this figure shows the tape  28  threaded up to approximately the read/write head  38 . It is further noted that since the interior of the leader path  82  is open between the threading tracks  176   a  and  176   b,  the magnetic tape  28  follows a shorter path through the tape drive  20 . For example, in FIG. 10, the magnetic tape  28  is shown taking a shorter path than that of the leader path  82  between the open end  220  of the leader path and the read/write head  38 . The path of the tape is constrained and defined by the following components of the tape drive  20  (FIGS.  1  and  10 ): (a) a first tape guide  240  (being, e.g., a low friction hydrodynamic bearing, in one embodiment manufactured from a ceramic composite), (b) a first tape cleaning blade  244  for removing debris from the tape  28 , (c) the read/write head  38 , (d) a second tape cleaning blade  248 , and (e) a second tape guide  252  (being also, in one embodiment, a hydrodynamic bearing). Note that the tape  28  is shown following the path defined by these components in FIG.  15 . Further note that the tape path is designed to accommodate high tape speeds through the tape drive  20 , such as a tape speed of 10 meters per second. In particular, the hydrodynamic bearings  240  and  252  are intended to facilitate such high tape speeds without damaging or tearing the tape  28 . 
     Referring now to the take up assembly  40 , it includes: 
     (a) the take up reel hub  42  (FIGS. 1,  11  and  12 ) for winding the tape  28  thereabout; 
     (b) a motor  256  (FIG. 11) for winding both the leader  80  and the data storage tape  28  about the reel assembly  40 ; 
     (c) two pairs of tape alignment flanges  260   a  and  260   b  (FIG.  13 ), wherein each of the pairs  260   a  and  260   b  includes a pair of substantially co-planar flanges  264  on opposite sides of the take up reel hub  42 , wherein each such pair  260   a  and  260   b  are parallelly spaced apart from the other two substantially co-planar flanges  264  included in the other pair of  260   a  and  260   b . Note that the pairs of  260   a  and  260   b  are parallelly spaced apart only marginally more than the width of the magnetic tape  28 ; 
     (d) two leader take up reels  270   a  and  270   b , wherein each of the threading bands  98  of the leader winds about a different one of the leader take up reels. Note that in the embodiment shown in, e.g., FIG. 13, the leader take up reel  270   a  is manufactured as a unit with the pair  260   a  of tape alignment flanges, and the leader take up reel  270   b  is manufactured as a unit with the pair  260   b  of tape alignment flanges. 
     The take up reel hub  42  includes outer caps  274   a  and  274   b  (e.g., FIG. 12) which secures therebetween the tape winding core  280  about which the magnetic tape  28  winds on the surface  284 . Note that each of the outer caps  274   a  and  274   b  has a cutout  296  therein, wherein the cutouts receive at least part of a core door mechanism  288  (also denoted simply as “door” herein) that pivots between: 
     (a) a closed position (FIGS.  13  and  15 ), wherein the arcuate surface  292 , in combination with the arcuate surface  284 , completes the cylindrical or circumferential surface about which the tape  28  winds when it is wound about the take up reel hub  42 ; and 
     (b) an open position (FIGS.  1  and  10 ), wherein an interior of the cutout  296  is accessible via the opening  300  (FIG.  10 ). 
     Additionally, note that pin  304  (FIG. 12) secures the door  288  in the cutout  296 . In particular, the pin  304  extends through hole  308  in the door  288  so that the door pivots on this pin. 
     During the threading of the tape  28  through the tape drive  20 , each of the threading bands  98  winds around a corresponding one of the leader take up reels  270   a  and  270   b  to which the threading band is attached. Note that prior to the pin  56  contacting the take reel hub  42 , the door  288  is biased in an open position by a spring  310  and remains open during the rotation of the take up reel assembly  40  until the spring bias is overcome as will be discussed hereinbelow. Subsequently, since the length of the leader  80  and its attachment positions on the leader take up reels  270   a  and  270   b  are such that when the hook subassembly  94  and the attached pin  56  reach the take up reel hub  42 , the subassembly hook and the pin enter the opening  300  and the pin lodges against the ledge  314  (FIGS.  12  and  14 ). Note that the ledge  314  is interior to the cylindrical surface composed of the surfaces  284  and  292  about which the tape  28  winds. Subsequently, the tape  28  commences to wind about the surface  284  of the tape winding core  280  until the surface  292  of the open door  288  is encountered. Accordingly, the tape  28  then commences to follow the surface  292  as shown in FIG.  14 . Since the typical tension on the magnetic tape  28  during this tape threading process is approximately one Newton, prior to the magnetic tape reaching the free end  318  (FIGS. 12 and 14) of the door  288 , the tape tension overcomes the bias of the spring  310  and the door  288  closes thereby enclosing the hook  94  and the pin  56  within the take up reel hub  42 . Thus, a substantially smooth and uniform circumferential surface (i.e., the combined surfaces  284  and  292 ) is provided for winding the magnetic tape  28  thereabout, since the tape does not contact any of: the leader  80 , the hook subassembly  94 , and the pin  56 . 
     Regarding the unwinding of the tape  28  and the leader  80  from the take up reel assembly  40 , this process is substantially the reverse of the winding process described immediately above. That is, once the innermost layer of the tape  28  wrapping the combined surfaces  284  and  292  unwraps past approximately the midway point along the surface  292  of the door  288 , the bias of the spring  310  overcomes the counter-bias of the tape and the door  288  opens thereby allowing the pin  56  and the hook subassembly  94  to freely exit the interior of the take reel hub  42 . Thus, once the pin  56  detaches from the take up reel hub  42 , the leader bands  98  commence unwinding from the leader take up reels  270   a  and  270   b.    
     FIGS. 16-19G show an alternative embodiment of the take up reel hub  42 , wherein an alternative configuration of the door mechanism or simply door (labeled  288   a ) and related components are shown. Referring to FIGS. 16 and 17, the take up reel hub  42  is substantially identical to the initial embodiment of the take up reel hub provided hereinabove. However, instead of the door being substantially outside of the tape winding core  280  when in the open position, the door  288   a  is substantially interior to the tape winding core when the door is open when as shown in FIG.  16 . In particular, the surface  292 , upon which the tape winds when the door  288   a  is closed, it is entirely within the tape winding core  280 . The door  288   a  has a first pivot shaft  350  centered on an axis  354  about which the door pivots (according to rotation arrow  356 , FIG.  16 ). The first pivot shaft  350  is attached to the first door plate  358 . The first door plate  358  extends from a free end  362  to an opposite end that is attached to (or integrally molded with) the generally arcuately shaped door face component  366  which has the surface  292  as a “front side”, and an opposing “back side” having a reinforced portion  370  to which the first door plate  358  is attached. Additionally, note that there is a second door plate  374  having the same shape as the first door plate  358 , wherein the two plates are aligned such that when viewing them along the axis  354 , their profiles are identical. Moreover, each of the first and second door plates  358  and  374  are similarly attached to the reinforced portion  370 . Additionally, although not shown, the second door plate  374  has attached to its side  378  (entirely hidden in the views of FIGS. 16 and 17) a second pivot shaft  350  that is substantially identical to the first pivot shaft  350 . However, the second pivot shaft  350  extends away from the side  378  along the axis  354  in the opposite direction from which the first pivot shaft  350  extends from the first door plate  358 . 
     The first and second door plates  358  and  374  are parallelly spaced apart but attached to one another by a post  382  that traverses the space between the two door plates. Note that the post  382  is offset from the axis  354  so that when the door  288   a  pivots about the axis  354 , the post follows a circular path about the axis  354 . Moreover, as an aside, note that there may be additional posts connecting the first and second plates  358  and  374  together as one skilled in the art will understand. 
     Attached to the post  382  is a spring  386 , wherein the spring extends between the post and a spring fastener  390  attached to the tape winding core  280  within a cutout  394 . During the rotation of the door  288   a  between the fully open position of FIG.  16  and the fully closed position of FIG. 17, the post  382  follows an arcuate path  396  (FIG. 18) about the axis  354 . Accordingly, the spring  386  changes position and configuration as the post moves along the arcuate path  396 . In particular, the spring has sufficient tensile strength to bias the post  382  to the end points  398  and  402  of the arcuate path  396 . Accordingly, the spring urges the door  288   a  to either enter and stay in a fully open position, or enter and stay in a fully closed position. Thus, if the door  288   a  is open and is urged to close so that the post  382  travels clockwise to a position beyond the midpoint of the path  396 , then the door  288  will, from that position on, be biased by the spring  386  to fully close. Conversely, when the door  288   a  is in the fully closed position and is subsequently urged to open so that the post  382  travels counterclockwise past the midpoint of the path  396 , then the door will be biased by the spring  386  to fully open. 
     FIGS. 19A-19G illustrate the closing of the door  288   a  at the completion of the threading of the tape  28  through the tape drive  20 . Accordingly, in FIG. 19A, the door  288   a  is shown in its fully open position while the take up reel hub  42  rotates in the direction of arrow  406 . Accordingly, no portion of the tape  28  encounters the take up reel hub  42 . Instead, the threading bands  98  of the leader  80  are being wound about the leader take up reels  270   a  and  270   b . (Note, each of the take up reels are substantially identical to those shown in the initial embodiment; in particular, the take up reels  270   a  and  270   b  of FIG.  13 . Further, note that for simplicity the tape alignment flange pairs  260   a  and  260   b  are not shown in FIGS.  16 - 19 G). 
     In FIG. 19B, a portion of the arcuately shaped door component  366  has entered the space between the threading bands  98  of the leader  80  due to the winding of the threading bands about the leader take up reels  270   a  and  270   b.    
     In FIG. 19C, as the take up reel hub  42  continues to rotate, the door  288   a  contacts the pin  56  which is coupled with the hook subassembly  94 . Note that as with the previous embodiment  288   a  of the door, the length of the leader  80  is such that when substantially fully wound around the leader take up reels  270   a  and  270   b , the coupling of the pin  56  and the hook subassembly  94  is positioned for contacting the door  288   a  as shown in the present figure. Accordingly, this contact causes the door  288   a  to commence pivoting clockwise about the first and second pivot shafts  350 . 
     In FIG. 19D, the door  288   a  is shown pivoting further in the clockwise direction, wherein the post  382  has rotated away from the initial end point position of  398  (FIG.  18 ). Note that it is an aspect of the present invention that for the portion of the profile of the first and second door plates  358  and  374  where the pin  56  contacts this profile, the profile is smooth and shaped so that the force induced on the door  288   a  by the pin does not induce a force in the direction of the pivot shafts  350  that could cause the door to bind on the shaft pins or break the shaft pins. 
     In FIG. 19E, the pin  56  has caused the door  288   a  to pivot sufficiently so that the post  288  is substantially at a midway position between the positions  398  and  402  (FIG.  18 ). Thus, the spring  386  is in a substantially maximally extended configuration. Moreover, note that the pin  56  and the hook subassembly stay  114  have begun to enter the recess  410  between: (a) the door plates  358  and  374  on the one side, and (b) the arcuately shaped door face component  356  on the other side. 
     In FIG. 19F, the position of the post  382  is such that the spring  386  is biasing the door  288   a  to close. Accordingly, the door  288   a  will close without further urging by the pin  56 . Thus, the backside of the arcuately shaped door face component  366  now contacts the pin  56  due to the spring  386  now urging the door  288   a  closed. Moreover, note that the pin  56  is now fully within the recess  410 . However, note that since both the pin  56  and the hook subassembly  94  extend substantially from the leader take up reel  270   a  to the leader take up reel  270   b , the pin and hook subassembly extend outside of the tape winding core  280  in the direction of the axis  354  (FIG.  16 ). 
     In FIG. 19G, the door  288   a  is shown fully closed. Accordingly, the tape  28  now extends: 
     (a) from the pin  56  within the interior of the cylindrical tape winding surface provided by the combination surfaces  284  and  292 , 
     (b) through the tape exit  414 , which may be no more than a mating of the end  418  of the door  288   a  with the tape winding core  280 , and 
     (c) to the exterior of the take up reel hub  42 . 
     Note that the tape  28  now commences to wind around the circumferential combinations of arcuate surfaces  284  and  292 . 
     When the tape  28  is being unwound from the take up reel hub  42  and the tape is to be unthreaded from the tape drive  20 , the illustrations of FIGS. 19A-19G occur in reverse order. However, note that the tension on the tape itself during the unwinding process is now used to urge the door  288   a  open and thereby overcome the door closing bias of the spring  386 . Thus, as the take up reel hub  42  rotates in the clockwise direction for unwinding the tape, the tape  28  causes the door  288   a  to rotate counterclockwise about the pivot shafts  350 , and the pin and hook subassembly are released from the interior of the tape winding core  280 . 
     The foregoing discussion of the invention has been presented for purposes of illustration and description. Further, the description is not intended to limit the invention to the form disclosed herein. Consequently, variation and modification commensurate with the above teachings, and within the skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain the best modes presently known of practicing the invention and to enable others skilled in the art to utilize the invention as such, or in other embodiments and with the various modifications required by their particular application or uses of the invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.

Technology Category: 3