Abstract:
In one embodiment, a tape cartridge includes: a housing; a reel rotatably disposed in the housing; a reel lock operatively coupled to the reel, the reel lock operative between a first position in which the reel is locked and a second position in which the reel is unlocked; one of the housing or the reel lock having an insert and the other of the housing or the reel lock having a receiver, the insert sized and shaped to fit closely into the receiver and the insert slidable in the receiver; and a damper operatively coupled between the housing and the reel lock when the reel lock is in the second position.

Description:
BACKGROUND 
   A widely used medium for storing data is magnetic tape. Tape cartridges are one of the most popular formats for storing data on tape. Two widely used tape cartridges are the dual reel cartridge and the single supply reel cartridge. In a dual reel tape cartridge, both the supply reel and the take-up reel are housed in the cartridge. In a single supply reel tape cartridge, the take-up reel is built into the tape drive along with an automatic tape threading mechanism. When a tape cartridge is not in use in a tape drive or tape player, it is possible for the reel(s) to rotate idly and cause the tape to lose tension and become partially unwound from the reel. To avoid this problem, tape cartridges often include some type of reel lock. 
   A common type of reel lock used in single supply reel cartridges includes a locking gear that engages teeth or other projections on the back of a reel drive gear that locks the reel when the cartridge is not installed in a tape drive. A spider washer pushes the locking gear out of the way into a disengaged position unlocking the reel when the cartridge is installed in the tape drive. In this disengaged position, the spider washer spins (with the reel) against the stationary locking gear. The spinning washer sometimes makes the locking gear wobble, oscillate up and down or otherwise vibrate within the free play tolerance of the alignment feature that couples the locking gear to the cartridge housing. At the higher tape speeds of some of the newer generation tape drives, the reel lock vibrating against the hard plastic cartridge housing can be noisy. Embodiments of the invention were developed to reduce these noisy vibrations. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective bottom side view of a single supply reel tape cartridge. 
       FIGS. 2 and 3  are cross section perspective views of a single supply reel tape cartridge constructed according to one embodiment of the invention showing the reel lock in the locked and unlocked positions, respectively. 
       FIG. 4  is a perspective view of the inside of the top of the housing of the cartridge shown in  FIGS. 2 and 3 . 
       FIG. 5  is a top perspective view of reel lock components of the cartridge shown in  FIGS. 2 and 3 . 
       FIG. 6  is an exploded perspective view of the components shown in FIG.  4 . 
       FIGS. 7 and 8  are perspective views of reel lock components of the cartridge shown in  FIGS. 2 and 3  showing the legs of the spider washer in the locked and unlocked position, respectively. 
       FIGS. 9 and 10  are perspective views showing reel lock and motion damping components of a tape cartridge constructed according to a second embodiment of the invention. 
       FIGS. 11 and 12  are perspective views showing reel lock and motion damping components of a tape cartridge constructed according to a third embodiment of the invention. 
       FIGS. 13 and 14  are perspective and section views, respectively, showing reel lock and motion damping components of a tape cartridge constructed according to a fourth embodiment of the invention. 
       FIG. 15  is a detail view of one embodiment of a damper portion of the components shown in  FIGS. 13 and 14 . 
       FIG. 16  is a detail view of another embodiment of a damper portion of the components shown in FIGS.  13  and  14 . 
   

   DESCRIPTION 
   Referring to  FIGS. 1-3 , a single reel tape cartridge  10  includes a housing  12  and a tape supply reel  14 . Housing  12  is a rectangular box-like structure configured to enclose a single reel of tape. Housing  12  is usually formed of plastic molded into two segments—a cover segment  18  and a base segment  20 . The tape is accessible to a tape drive through an access window  24 . A door  26  covers access window  24  when cartridge  10  is not installed in a tape drive. 
   Referring to  FIGS. 2 and 3 , tape reel  14  includes disc shaped top and bottom flanges  28  and  30  and an annular hub  32 . A circular reel gear  34  is positioned at the bottom of hub  32 . Reel gear  34  is the operative interface between a tape drive and the tape reel. Reel gear  34  is engaged by a mating coaxial gear in the drive mechanism of a tape drive. Reel gear  34  is accessed by the tape drive through an opening  36  in the base  20  of housing  12 . 
   Referring now to  FIGS. 2-8 , reel lock  38  includes a spider washer  40 , a locking gear  42  and locking posts  44  positioned at spaced apart locations around the top of reel gear  34 . The ends  46  of locking posts  44  are sized and shaped to fit into locking gear teeth  48 . Three locking posts  44  spaced at equal intervals around reel gear  34  are just one example of a suitable structure for the operative engagement between locking gear  42  and reel gear  34 . Other examples include a full or partial set of gear teeth on the top of reel gear  34  instead of the posts used in the embodiment shown in  FIGS. 2-8  or, instead of using a locking gear  42 , this locking member could be constructed as a flat disk having one or more posts projecting down to engage teeth on top of the reel gear. 
   Legs  50  of spider washer  40  project through holes  52  in reel gear  34 . Holes  52  are positioned at the gaps  54  between reel gear teeth  56  as best seen in  FIGS. 6-8 . Spider legs  50  project into gaps  54  between reel gear teeth  56 , as best seen in FIG.  7 . Preferably, each hole  52  and correspondingly each spider leg  50  spans the gap  54  between adjacent gear teeth to prevent jamming in the teeth of the tape drive gear. Each hole  52  and spider leg  50  could also be made to span two or more gaps  54 , in which case hole  52  would extend through one or more gear teeth. 
   Locking gear  42  is movable in only one dimension, along the axis of rotation of reel  14 . Locking gear  42  is nominally fixed in the other dimensions by an alignment feature  57  that couples gear  42  to cartridge housing  12 . In the embodiment shown in  FIGS. 2-8 , alignment feature  57  includes an insert  58  formed on or integral with cover segment  18  of housing  12  and a mating receiver  60  formed on or integral with the top  62  of locking gear  42 . In this embodiment, insert  58  is constructed as a ridge on housing cover  18 . Receiver  60  on locking gear  42  receives ridge  58  on cartridge housing  12  to align locking gear  42  over spider washer  40  and locking posts  44 . A biasing spring  64  between cartridge housing  12  and locking gear  42  urges locking gear  42  against spider washer  40  and locking posts  44 . This biasing mechanism  64  pushes spider legs  50  down into reel gear teeth  56  and keeps reel lock  38  locked when tape cartridge  10  is not installed in a tape drive. A damper  65  is interposed between locking gear  42  and housing  12 . In the embodiment shown in  FIGS. 2-8 , damper  65  is constructed as a resilient pad  66  surrounding slot  60  on locking gear  42 . Resilient pad  66  is slightly deeper than receiver  60  so that pad  66  protrudes above receiver  60 . 
   In operation, as the drive motor gear in a tape drive engages reel gear  34 , the tips of the drive motor gear push on spider legs  50  to drive spider washer  40  up into reel gear  34 . This action moves locking gear  42  up and off locking posts  44  to unlock reel lock  38 , as best seen by comparing  FIGS. 2 and 3  and  FIGS. 7 and 8 . Spider washer  40  and biasing spring  64  serve as the actuator for reel lock  38 . Spider washer  40  acts as a release mechanism to disengage the locking member, locking gear  42  in this embodiment, from reel  14  and unlock reel lock  38  when the tape drive engages the reel  14 . Spring  64  serves as a biasing mechanism to urge the locking member, locking gear  54 , towards the locked position. When locking gear  42  is pushed up to the unlocked position, shown in  FIGS. 3 and 8 , resilient pad  66  is driven into contact with housing  12  at the area surrounding ridge  58  as ridge  58  slides deeper into receiver  60 . Thus, while reel lock  38  is in the unlocked position, resilient pad  66  is pressed between locking gear  62  and housing  12  to dampen any vibration in locking gear  62  and insulate housing  12  against any such vibration. 
   It is desirable that spider legs  50  project out flush with the tips  68  of reel gear teeth  56  to maximize the vertical travel of locking gear  42  when reel gear  34  is engaged by the tape drive. The depth of locking gear teeth  48  should be slightly less than the depth of reel gear teeth  56  (or less than the distance spider legs  50  project into gaps  54  in reel gear teeth  56  if less than the full depth of the teeth) to ensure locking gear  42  clears locking posts  44  to fully release the lock  50 . Forces are transmitted between locking gear  42  and spider washer  40  through a button  70  on the bottom  72  of locking gear  42 . The frictional interface/bearing surface between spider washer  40  (which rotates with tape reel  14 ) and locking gear  42  (which is rotationally fixed to cartridge housing  12 ) occurs at button  70 . The frictional interface at button  70  is at the center of rotation of the reel so the radius of button  70  can be made relatively small to minimize frictional drag and wear. 
     FIGS. 9-10  and  11 - 12  illustrate alternative configurations for alignment feature  57  and the associated damper  65 . Referring first to  FIGS. 9 and 10 , the alignment feature includes a hub  74  and a projecting insert  76  on cover segment  18  of housing  12  and a mating receiver  78  on top  62  of locking gear  42 . In this embodiment, insert  76  is constructed as raised spokes on housing cover  18  and the damper is constructed as disc shaped resilient pads  80  affixed to housing  12  between spokes  76 . When locking gear  42  is pushed up to the unlocked position, receiver  78  is driven into contact with pads  80  as spokes  76  slide deeper into receiver  80 . Thus, while reel lock  38  is in the unlocked position, resilient pads  80  are pressed between locking gear  42  and housing  12  to dampen any vibration in locking gear  62  and insulate housing  12  against any such vibration. 
   Referring to  FIGS. 11 and 12 , the alignment feature includes insert  82  on cover segment  18  of housing  12  and a mating receiver  84  on top  62  of locking gear  42 . In this embodiment, insert  82  is constructed as intersecting ridges on housing cover  18  and the damper is constructed as a disc shaped resilient pad  86  affixed to housing  12  surrounding ridges  82 . When locking gear  42  is pushed up to the unlocked position, receiver  84  is driven into contact with pad  86  as ridges  82  move deeper into receiver  84 . Thus, while reel lock  38  is in the unlocked position, resilient pad  86  is pressed between locking gear  42  and housing  12  to dampen any vibration in locking gear  62  and insulates housing  12  against any such vibration. 
   Referring to  FIGS. 13-16 , alignment feature  57  includes the ridge type insert  58  and mating receiver  60  of  FIGS. 2-8 , but damper  65  consists of a resilient pad  88  affixed to or integral with the outside of ridge  58 . In one embodiment, shown in the detail view of  FIG. 15 , resilient pad  88  is formed from a bristling material lining the outside of ridge  58 . In another embodiment, shown in the detail view of  FIG. 16 , resilient pad  88  is formed as a multitude of tiny fingers molded along the outside of ridge  58 . In these embodiments, pad  88  creates a light resilient interference fit between ridge  58  and receiver  60  to dampen any vibration in locking gear  62  and insulate housing  12  against any such vibration. 
   Although it is expected that resilient pads  66 ,  80  and  86  will typically be formed from rubber or another suitable elastomeric material, any resilient material that provides the necessary or desired damping may be used. “Teeth” means any sharp angled, rounded or other combination of protrusions and indentations. 
   The present invention has been shown and described with reference to the foregoing exemplary embodiments. It is to be understood, however, that other forms, details, and embodiments may be made without departing from the spirit and scope of the invention which is defined in the following claims.