Abstract:
A data storage tape cartridge has a housing, at least one tape reel assembly rotatably disposed within the housing, a storage tape wound about a tape winding surface of the tape reel assembly, and a brake assembly. The brake assembly includes a brake plate and a brake button. When the brake assembly is an unlocked position, a depression in the brake plate mates with a protruding member of the brake button to limit vibration of the brake assembly, thereby limiting noisy vibration of cartridge.

Description:
THE FIELD OF THE INVENTION  
       [0001]     The present invention relates to data storage tape cartridges. More particularly, it relates to a data storage tape cartridge brake assembly, that when disengaged, limits vibration of the brake assembly itself while the cartridge is operating.  
       BACKGROUND  
       [0002]     Data storage tape systems have been used for decades in the computer, audio, and video fields. The data storage tape system includes a tape drive and one or more data storage tape cartridges. In one data storage/drive system, storage tape is driven along a tape path between a first tape reel assembly within the cartridge and a second tape reel assembly within the drive. Regardless of exact form, the data storage tape system continues to be a popular format for recording large volumes of information for subsequent retrieval and use.  
         [0003]     With the above in mind, a data storage tape cartridge generally consists of an outer shell or housing maintaining at least one tape reel assembly and a length of magnetic storage tape. The storage tape is wrapped about a hub of the tape reel assembly and is driven through a defined path by a driving system. The housing normally includes a separate cover and a separate base. Together, the cover and the base form an opening (or window) at a forward portion of the housing facilitating access to the storage tape by a read/write head upon insertion of the data storage tape cartridge into the tape drive. The interaction between the storage tape and the head can occur within the housing (i.e., a mid-tape load design) or exterior to the housing (i.e., a helical drive design). Where the head/storage tape interaction is exterior to the housing, the data storage tape cartridge normally includes a single tape reel assembly employing a leader block or similar device. Alternately, where the head/storage tape interaction is within the housing, a dual tape reel cartridge configuration is typically employed.  
         [0004]     Regardless of the number of tape reel assemblies associated with a particular data storage tape cartridge, the tape reel assembly (also known as a spool) generally includes a hub and one or more reel flanges. In general, the hub includes a core that defines a tape winding surface. The reel flanges are optional, and if employed, are disposed at opposite ends of the hub. To this end, the flanges have a spacing slightly wider than a width of the storage tape to facilitate winding of the storage tape onto, and off of, the tape winding surface.  
         [0005]     With this in mind, some form of a brake mechanism is provided to secure the tape reel assembly within the housing during periods of storage. The brake mechanism is generally movable between a locked (i.e., storage) position, and an unlocked position that permits the tape reel assembly to rotate during read/write processing.  
         [0006]     For example, the prior art brake mechanisms are normally provided with engagement teeth, or other high friction surface, configured to mate with a corresponding brake surface of the hub of the tape reel assembly. When the data storage tape cartridge is not engaged with the tape drive (i.e., when the cartridge is being handled), the teeth of the brake mechanism are engaged with the brake surface of the hub to prevent rotation of the tape reel assembly. That is to say, the prior art data storage tape cartridges are designed to prevent the rotation of the tape reel assembly when the cartridge is disengaged from the tape drive such that the storage tape, for example, does not inadvertently unravel from the tape reel assembly.  
         [0007]     While the above-described brake mechanism addresses unintended unraveling of the storage tape, it can also vibrate and/or wobble within the cartridge housing during read/write processing. In particular, the mass of the brake button during dynamic read/write processing, is known to vibrate substantially in a fundamental frequency. The vibration is accentuated across other frequencies when rotating portions of the tape reel assembly are eccentric, or imbalanced. In addition, any imbalance in the brake mechanism, or contact of the brake mechanism with the rotating tape reel assembly, induces vibrations that result in audible noise during read/write processing.  
         [0008]     Data storage tape cartridges have proven highly desirable in the storage and protection of large volumes of retrievable electronic data. Recent advance in data storage tape cartridges have resulted in larger data storage capacities and faster read/write processing. With this in mind, a need exists to reduce deleterious vibrations in data storage tape cartridges that produce noise.  
       SUMMARY  
       [0009]     One aspect of the present invention is related to a data storage tape cartridge. The data storage tape cartridge includes a housing, at least one tape reel assembly rotatably disposed within the housing, a storage tape wound about a tape winding surface of the tape reel assembly, and a brake assembly. The housing includes a base and a cover that combine to define an enclosed region. In addition, the base defines a central opening. The brake assembly is aligned with the central opening and is nested between the tape reel assembly and the cover. In this regard, the brake assembly includes a brake button and a brake plate. The brake button defines a hub side including a protruding member. The brake plate defines a cover side defining depression. When the brake assembly is an unlocked position, the depression of the brake plate mates with the protruding member of the brake button to limit vibration of the brake assembly.  
         [0010]     Another aspect of the present invention is related to a brake assembly for a data storage tape cartridge. The brake assembly includes a brake button defining a convex protruding member, and a brake plate defining a concave depression sized to receive the convex protruding member. In this regard, the concave depression defines a radius of curvature that is greater than a radius of curvature of the convex protruding member.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Embodiments of the invention are better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.  
         [0012]      FIG. 1  illustrates a perspective, exploded view of a data storage tape cartridge according to one embodiment of the present invention;  
         [0013]      FIG. 2  illustrates a brake plate according to one embodiment of the present invention;  
         [0014]      FIG. 3  illustrates a cross-sectional view of the brake plate illustrated in  FIG. 2 ;  
         [0015]      FIG. 4  illustrates a perspective view of a brake button according to one embodiment of the present invention;  
         [0016]      FIG. 5  illustrates a cross-sectional view of the brake button illustrated in  FIG. 4 ;  
         [0017]      FIG. 6  illustrates a perspective view of components of a brake assembly according to one embodiment of the present invention;  
         [0018]      FIG. 7  illustrates a cross-sectional view of an aligned and operably assembled brake assembly not including a spring and according to one embodiment of the present invention; and  
         [0019]      FIG. 8  illustrates a cross-sectional view of an assembled data storage tape cartridge according to one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]      FIG. 1  illustrates an exemplary single reel data storage tape cartridge  20  according to one embodiment of the present invention. Generally, the single reel data storage tape cartridge  20  includes a housing  22 , a single tape reel assembly  26 , a storage tape  28  coupled to a leader block  30 , and a brake assembly  32 . The single tape reel assembly  26  is disposed within the housing  22 . The storage tape  28 , in turn, is wound about the single tape reel assembly  26  and includes a leading end  33  attached to the leader block  30 . As a point of reference, while a single reel data storage tape cartridge  20  is shown, the present invention is applicable to other cartridge configurations, such as dual reel cartridge configurations.  
         [0021]     The housing  22  is sized for reception by a typical tape drive (not shown). Thus, the housing  22  exhibits a size of approximately 125 mm×110 mm×21 mm, although other dimensions are equally acceptable. With this in mind, the housing  22  is defined by a first housing section  34  and a second housing section  36 . In one embodiment, the first housing section  34  forms a cover whereas the second housing section  36  forms a base. As used throughout the Specification, directional terminology such as “cover,” “base,” “upper,” “lower,” “top,” “bottom,” etc., is employed for purposes of illustration and description as related to the particular Figure shown.  
         [0022]     The first and second housing sections  34  and  36 , respectively, are sized to be reciprocally mated to one another to form an enclosed region  37  and are generally rectangular, except for one corner  38  that is preferably angled and forms a tape access window  40 . The tape access window  40  serves as an opening for the storage tape  28  to exit from the housing  22  such that the storage tape  28  can be threaded to a tape drive (not shown) when the leader block  30  is removed from the tape access window  40 . Conversely, when the leader block  30  is engaged in the tape access window  40 , the tape access window  40  is covered.  
         [0023]     In addition to forming a portion of the tape access window  40 , the second housing section  36  also forms a central opening  42 . The central opening  42  facilitates access to the single tape reel assembly  26  by a drive clutch portion of the tape drive (not shown). A raised ring  44  is formed concentrically about the central opening  42  and is configured to couple with a complementary groove (not shown) formed in the tape reel assembly  26 .  
         [0024]     The tape reel assembly  26  comprises a hub  50 , an upper flange  52  and a lower flange  54 . The upper and lower flanges  52 ,  54  extend in a radial fashion from opposing sides of the hub  50 , respectively, and cooperate to retain multiple wraps of the storage tape  28  about the hub  50  and between the flanges  52 ,  54 . In one embodiment, the hub  50  defines a tape winding surface (covered by the storage tape  28 ) and brake posts  56  extending axially from an interior surface  58  of the hub  50 . In one embodiment, a top portion of each of the brake posts  56  defines an engagement surface  60 . In another embodiment, the brake posts  56  form walls or wall sections that extend axially from an interior surface  58  of the hub  50 .  
         [0025]     The storage tape  28  is preferably a magnetic tape of a type commonly known in the art. For example, the storage tape  28  may consist of a balanced polyethylene naphthalate (PEN) based material coated on one side with a layer of magnetic material dispersed within a suitable binder system and coated on the other side with a conductive material dispersed within a suitable binder system. Acceptable magnetic tape is available, for example, from Imation Corp., of Oakdale, Minn.  
         [0026]     The leader block  30  covers the tape access window  40  and facilitates retrieval of the storage tape  28 . In general terms, the leader block  30  is shaped to conform to the window  40  of the housing  22  and to interact with the tape drive (not shown) by providing a grasping surface for the tape drive to manipulate in delivering the storage tape  28  to the read/write head. In this regard, the leader block  30  can be replaced by other components, such as a dumb-bell shaped pin. More over, the leader block  30 , or a similar component, can be eliminated entirely, such as with a dual reel cartridge design.  
         [0027]     The brake assembly  32  includes a brake plate  70 , a brake button  72 , and a spring  74 . The brake plate  70  is sized to be received within the hub  50  of the tape reel assembly  26 . In particular, the brake plate  70  defines slots  80  that are sized to receive the brake posts  56 , such that the brake posts  56  slide within the slots  80 . The brake button  72  is sized to be coaxially received by the spring  74 , and mate with the brake plate  70  when the brake assembly  32  is disengaged.  
         [0028]     When the data storage tape cartridge  20  is idle, the brake button  72  is biased by the spring  74  such that the brake button  72  is engaged with the brake posts  56  of the hub  50  to selectively “lock” the single tape reel assembly  26  against the raised ring  44 .  
         [0029]     During use, a drive clutch portion of a tape drive (not shown) displaces the brake plate  70  axially upward, thus displacing the brake button  72  axially upward to disengage the brake button  72  from the brake posts  56  of the hub  50 . A subsequent further axial upward movement of the drive clutch displaces the tape reel assembly  26  out of engagement with the raised ring  44 , prior to rotating the tape reel assembly  26  for access to the storage tape  28 . In this manner, the drive clutch compresses the spring  74  such that the brake plate  70  and the brake button  72  are in contact with each other during read/write processing.  
         [0030]      FIG. 2  illustrates a perspective view of the brake plate  70  according to one embodiment of the present invention. The brake plate  70  defines a platen  90  and legs  92  extending from the platen  90 . The platen  90  defines a first side  94  and a second side  96 . In one embodiment, the first side  94  is a cover side, and the second side  96  is a base side. In addition, the platen  90  defines the slots  80  and a depression  98  on the cover side  94 . In one embodiment, the depression  98  is a hemi-spherical depression formed in the cover side  94  of the platen  90 .  
         [0031]     As a point of reference, the slots  80  project through the platen  90  and are generally sized to slidingly receive the brake posts  56  ( FIG. 1 ). While three slots  80  are illustrated in  FIG. 2 , it is to be understood that one slot  80  is acceptable, as is an embodiment where more than three slots are defined in the platen  90 .  
         [0032]     In general terms, the legs  92  extend from the base side  96  of the platen  90 . In one embodiment, the platen  90  defines a generally triangular shape and includes three legs  92  extending from the base side  96 . As illustrated, the legs  96  are generally oriented and extend from vertices of the triangular platen  90 , although other locations for the legs  90  are also acceptable.  
         [0033]     In an exemplary embodiment, the brake plate  70  is formed of a durable, non-magnetizing material. For example, the brake plate  70  is preferably formed of polymeric materials that are durable. In one embodiment, the brake plate  70  is formed of Acetal (polyoxymethylene), a high performance engineering polymer, although other polymeric materials, such as nylons and polyesters, are also acceptable.  
         [0034]      FIG. 3  illustrates a cross-sectional view of the brake plate  70  showing the depression  98  according to one embodiment of the present invention. The depression  98  is formed in the cover side  94  of the platen  90 , and in one embodiment is concave in hemi-spherical cross-section and defines a radius of curvature R P . In one embodiment, the radius of curvature R P  is between 0.25-2 inch, preferably the radius of curvature R P  is between 0.5-1.5 inch, and more preferably the radius of curvature R P  is approximately 1 inch.  
         [0035]      FIG. 4  illustrates a perspective view of the brake button  72  according to one embodiment of the present invention. The brake button  72  defines a first side  100  opposite a second side  102 , and an optional flange  104  extending radially between the first side  100  and the second side  102 . In one embodiment, the first side  100  is a cover side, and the second side  102  is a hub side. In this regard, in one embodiment the hub side  102  of the brake button  72  defines a brake surface  106  and a central protruding member  108 .  
         [0036]     In general, the brake button  72  is sized to coaxially receive the spring  74  ( FIG. 1 ). In this regard, the spring  74  is mounted circumferentially into the brake button  72  from the first side  100 . The brake surface  106  is generally a high friction surface. In one embodiment, the brake surface  106  defines a plurality of teeth configured to frictionally mate with the engagement surface  60  of the brake posts  56  ( FIG. 1 ).  
         [0037]     The protruding member  108  extends axially from the hub side  102 . In one embodiment, the protruding member  108  defines a convex hemi-spherical protrusion that is centrally located on a central axis of the brake button  72 .  
         [0038]     In another embodiment, the cover side  94  of the platen  90  defines a protruding member that defines a convex hemi-spherical protrusion centrally located on a central axis of the platen  90 , and the hub side  102  of the brake button  72  defines a depression that is concave in hemi-spherical cross-section.  
         [0039]     In an exemplary embodiment, the brake button  72  is formed of a durable, non-magnetizing material. For example, the brake button  72  is preferably formed of polymeric materials that are durable. In one embodiment, the brake plate  70  is formed of nylon, such as nylon 6-6, a high performance-engineering polymer, although other polymeric materials, such as Acetal (polyoxymethylene) and polyesters, are also acceptable.  
         [0040]      FIG. 5  illustrates a cross-sectional view of the brake button  72  according to one embodiment of the present invention. In an exemplary embodiment, the brake button  72  defines an interior wall  110  and a detent  112  that together form a spring well  114  sized to receive the spring  74  ( FIG. 1 ). In one embodiment, the detent  112  forms a wall or a wall section that extends radially about an inner surface the brake button  72 .  
         [0041]     The protruding member  108  extends centrally along a central axis from the hub side  102 . In this regard, the convex hemi-spherical protruding member  108  defines a radius R B . In one embodiment, the radius R B  is between 0.06-1 inch, preferably the convex hemi-spherical protruding member  108  defines a radius R B  of between 0.07-0.5 inch, and more preferably the convex hemi-spherical protruding member  108  defines a radius R B  of approximately 0.125 inch.  
         [0042]      FIG. 6  illustrates a perspective view of the brake plate  70  oriented relative to the brake button  72  according to one embodiment of the present invention. In this regard, the brake button  72  is shown suspended above and non-aligned with the brake plate  70  to illustrate the protruding member  108  relative to the depression  98 . When properly aligned and operably assembled, the cover side  94  of the brake plate  70  is adjacent the hub side  102  of the brake button  72 . In this manner, the depression  98  formed by the brake plate  70  is configured to receive the protruding member  108  of the brake button  72 .  
         [0043]      FIG. 7  illustrates a cross-sectional view of a properly aligned and operably assembled brake assembly  32  with the spring  74  ( FIG. 1 ) not shown for ease of illustration.  
         [0044]     In a preferred embodiment, the platen  90  defines a concave hemi-spherical depression  98  that is slightly larger than the convex hemi-spherical protruding member  108  on the brake button  72 . When the brake plate  70  and the brake button  72  are coaxially aligned, the protruding member  108  is received within the depression  98  in a stable, equilibrating orientation.  
         [0045]     For example, the depression  98  defines a radius R P  ( FIG. 3 ) that is greater than the radius R B  ( FIG. 5 ) of the protruding member  108 . In this manner, a majority of an exterior surface of the protruding member  108  is received by the depression  98  such that any lateral rocking motions of the brake button  72  relative to the brake plate  70  are constrained by, and thus dampened, by the brake plate  70  depression  98 . Thus, the depression  98  forms a trough or a well that dampens movement of the brake button, and in particular movement of the protruding member  108 , such that vibrations are minimized and/or greatly reduced (as is any possible relative motion between the brake plate  70  and the brake button  72 ). In other words, the depression  98  forms a trough or a well that defines a low potential energy state for the protruding member  108 , such that relative motion between the brake plate  70  and the brake button  72  is dampened/reduced.  
         [0046]      FIG. 8  illustrates a cross-sectional view of an assembled data storage tape cartridge  20  according to one embodiment of the present invention. The cartridge  20  is in an “in-hand” configuration ready for insertion into a tape drive (not shown) for read/write processing.  
         [0047]     The brake assembly  32  is engaged with the tape reel assembly  26  such that the tape reel assembly  26  cannot rotate or move axially. In this manner, the tape reel assembly  26  is “locked” and the brake assembly  32  is in a “locked position,” which is the case whenever the data storage tape cartridge  20  is not in a tape drive (i.e., the cartridge  20  is in hand). For ease of illustration, the storage tape  28  ( FIG. 1 ) has been omitted from the view of  FIG. 5A .  
         [0048]     The hub  50  of the tape reel assembly  26  and the brake assembly  32  are axially aligned with the opening  42 . As assembled, the brake plate  70  and the brake button  72  are disposed within the hub  50 , and the coiled spring  74  is disposed co-axially about the brake button  72 .  
         [0049]     The coiled spring  74  biases the brake button into the tape reel assembly  26  such that the engagement surface(s)  60  of the brake posts  56  are mated with the brake surface  106  of the brake button  72 . To this end, the brake button  72  impedes rotation of the tape reel assembly  26 , and the cartridge  20  is locked.  
         [0050]     As a point of reference, the data storage tape cartridge  20  is shown readied for insertion into and as a part of a tape drive system (not shown), where the tape drive system would include the data storage tape cartridge  20  and a motor-driven drive clutch. During use, the cartridge  20  is inserted into the tape drive and the drive clutch engages with the brake assembly  32 . More particularly, the drive clutch raises the brake plate  70  up and along the brake posts  56  (approximately 0.090 inches) until the brake surface  106  of the brake button  72  is disengaged from the brake posts  56 . Consequently, the depression  98  contacts the protruding member  108  as the risen brake plate  70  disengages the brake button  72  from the hub  50 . Thus, the tape reel assembly is “unlocked” and the configured for rotation in a read/write process.  
         [0051]     During a read/write process, the brake plate  70  rotates under the influence of the drive clutch. In this regard, the brake plate  70  and the brake button  72  comprise rotating wear components within the cartridge  20 . With additional reference to  FIG. 7 , the depression  98  of the rotating brake plate  70  combines with the protruding member  108  of the brake button  72  to dampen vibrations caused by eccentricities within the tape reel assembly  26 /brake assembly  32 . In particular, eccentricities caused, for example, by a slight mis-alignment of the cartridge  20  within the tape drive, or by variations in mass distribution within the tape reel assembly  26 , might cause lateral motion (i.e., wobbling) of the brake plate  70 . However, the incidence of lateral motion in the rotating brake plate  70  is quelled, or dampened, by the interaction of the protruding member  108  within the depression  98 . Thus, vibration of the components of the cartridge  20  during read/write processing is greatly reduced or eliminated (since the relative motion of the rotating wear components is reduced or eliminated) through the interaction of the brake plate  70  and the brake button  72 .  
         [0052]     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.