Abstract:
Structure of a lower case that reinforces a recording tape cartridge. At an inner side of the lower case, an annular projecting portion is provided along and at an inner side of a reel area rib that demarcates a reel area, raising stiffness of the case. At a periphery of a hole for positioning, which is formed in an outer face of the lower case, a recessed surface, which provides a height direction reference surface, is formed. At the inner side of the lower case, a boss is formed in correspondence to the hole for positioning. The boss is located along an outer face of the reel area rib. A thickness-enhancing portion is formed at the periphery of a base portion of the boss. Thus, thickness at the reference surface, that is, the recessed surface, is substantially the same as thickness at portions therearound.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a recording tape cartridge which accommodates a reel on which a recording tape such as a magnetic tape or the like is wound, the recording tape cartridge being loaded at a drive device when in use.  
           [0003]    2. Description of the Related Art  
           [0004]    Recording tapes such as magnetic tapes and the like are used as recording media for saving data (information) for computers and the like, and for audio use, video use and the like. In order to prevent damage to a recording surface of such a recording tape, due to adherence of dust or the like to the recording surface, finger contact or the like, such a recording tape is employed in a recording tape cartridge. In this recording cartridge, the recording tape is wound onto a reel and the reel is rotatably accommodated in a case formed of resin.  
           [0005]    “Single reel cartridges”, in which a recording tape wound onto a single reel is accommodated in a case (these are principally used for back-up of information for computers and the like), two-reel cartridges, which are provided with two reels for winding and unwinding (for example, audio cassettes, video cassettes and the like), and the like are known as recording tape cartridges. When information is to be recorded or replayed with one of these recording tape cartridges, the recording tape cartridge is loaded at a drive device (a recording/replaying device).  
           [0006]    In a state in which the recording tape cartridge has been loaded into the drive device and the case has been positioned in the drive device, the recording tape is drawn out of the case. This recording tape is guided along a predetermined tape path and brought close to a recording/replaying head of the drive device. Hence, information is recorded onto the recording tape and/or information that has been recorded on the recording tape is replayed.  
           [0007]    Here, as shown in FIGS. 5 and 6, substantially circular arc-shaped reel area ribs  202  are standingly provided in a case  200  (an upper case is omitted from these drawings). The reel area ribs  202  bound a reel area  204  which accommodates a reel (not shown). The reel is urged downward by a spring (not shown). Accordingly, in order to increase rigidity of the case  200  in accordance with pressing force of the spring, the case  200  is made slightly thicker at the reel area  204 .  
           [0008]    Reference holes  208  and  210  are recessedly provided at two locations in an outer face of a lower case  206 , which locations are obverse to a region at an outer side of the reel area  204  (and correspond to inner portions of bosses  205  and  207 , which are projectingly provided at an inner face side of the lower case  206 ). By the reference holes  208  and  210  being insertingly fitted onto pins  214  disposed in a drive device  212 , positioning of the case  200  in horizontal directions with respect to a drive device  212  is achieved.  
           [0009]    Reference surfaces  208 A and  210 A, which are recessed from the outer face of the lower case  206 , are provided at entry aperture portions of the reference holes  208  and  210 , respectively. When the reference holes  208  and  210  are insertingly fitted onto the pins  214 , the reference surfaces  208 A and  210 A abut against pedestal seats  214 A provided at the pins  214 , and thus positioning of the case  200  in a height direction with respect to the drive device is achieved.  
           [0010]    Because the reference surfaces  208 A and  210 A are recessedly provided in the lower case  206 , plate thickness at the reference surfaces  208 A and  210 A is thinner than at other portions of the lower case  206 , such as, for example, portions that form regions peripheral to the reference surfaces  208 A and  210 A.  
           [0011]    As a result, differences in plate thickness between the reference surfaces  208 A and  210 A and the peripheries of the reference surfaces  208 A and  210 A are large. As a result, sinking after forming, and flow lines and the like can occur. Moreover, mold transcription is variable, and texture, brightness and the like are irregular, which has an adverse effect on the appearance of the cartridge.  
         SUMMARY OF THE INVENTION  
         [0012]    In consideration of the circumstances described above, an object of the present invention is to assure strength of a reel area of a recording tape cartridge. In addition, an object of the present invention is to provide a recording tape cartridge in which, when the recording tape cartridge is molded, deleterious effects of sinking and the like on external appearance do not occur.  
           [0013]    A first aspect of the present invention provides a recording tape cartridge which accommodates a recording tape and is loaded at a drive device for use, the recording tape cartridge comprising: a reel at which the recording tape is wound; and a case which includes an inner face on which the reel is disposed, the case accommodating the reel, wherein the case includes: a rib which protrudes on the inner face and bounds a region accommodating the reel, and an annular protruding surface formed on the inner face, which surface is adjacent to and located at an inner side of the rib.  
           [0014]    A second aspect of the present invention provides a recording tape cartridge which accommodates a recording tape and is loaded at a drive device for use, the recording tape cartridge including: a reel at which the recording tape is wound; and a case which includes an inner face on which the reel is disposed, the case accommodating the reel, wherein the case includes: an outer face obverse to the inner face; a recessed surface at the outer face for providing a reference surface for a height direction of the recording tape cartridge; and a protruding surface formed at the inner face for a region corresponding to at least the recessed surface.  
           [0015]    In a recording tape cartridge of the aspects described above, ribs which define the region accommodating the reel are provided protruding up from the inner face of the case, and holes for positioning are formed in the outer face in correspondence with a region outward from the ribs. Recessed surfaces are formed circumferentially to the holes, projecting portions are formed at the inner face in correspondence with the holes and structure wall portions of the holes, and protruding surfaces are formed circumferentially to base portions of the projecting portions. It is generally preferable that thicknesses of the case defined by the recessed surfaces and the protruding surfaces are made substantially equal to thicknesses at locations around the protruding surfaces of the case.  
           [0016]    As described above, in the case of a recording tape cartridge that is loaded at a drive device and used, the reel area ribs are provided, and the reel area ribs define the reel area accommodating the reel on which the recording tape is wound.  
           [0017]    The reference surfaces are recessedly formed in the outer face of the case, at positions that correspond to the region at an outer side of the reel area ribs, that is, obverse to the region, and serve as references for positioning in the height direction of the case in the drive device. At the inner side of the reel area ribs, the annular protruding surface, that is, a protruding portion, is provided in the reel area. Portions other than the reel area ribs that are thinner because of the reference surfaces are made thicker at the inner face side by thickening portions.  
           [0018]    Thus, because the annular protruding portion is protrudingly provided at the inner side of the reel area ribs, rigidity of the case can be improved. Moreover, because the portions that would be thinner because of the reference surfaces are made thicker by the annular protruding portion and the thickening portions, differences in thickness with respect to positions surrounding the reference surfaces, that is, the differences in thickness between positions at the reference surfaces and positions surrounding the reference surfaces, can be made smaller, and variations in pressure during molding can be made smaller. Consequently, sinking after forming and/or flow lines and the like are less likely to occur at the peripheries of the reference surfaces. Further, mold transference for higher precision with regard to brightness and/or texture can be provided.  
           [0019]    Furthermore, because the annular protruding portion is protrudingly provided at the inner side of the reel area ribs, resin circulates more easily when the reel area ribs are formed. That is, propagation becomes easier. Thus, short shot of the reel area ribs is less likely to occur. Furthermore, because the annular protruding portion is provided in the reel area, if the reel is inclined when the reel tape cartridge is not in use or the like, then the annular protruding portion will abut against outer edge portions of the reel. Accordingly, tilting of the reel can be restrained. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is an exploded perspective view showing overall structure of a recording tape cartridge relating to an embodiment of the present invention.  
         [0021]    [0021]FIG. 2 is a view showing a sectional view along the lines  2 - 2  in FIG. 1 and positioning pins of a drive device.  
         [0022]    [0022]FIG. 3 is a view showing another example of a sectional view along the lines  2 - 2  in FIG. 1 and the positioning pins of the drive device.  
         [0023]    [0023]FIG. 4A is a sectional view showing an inclined state of a reel in a situation in which an annular protruding portion is not protrudingly provided in a reel area.  
         [0024]    [0024]FIG. 4B is a sectional view showing an inclined state of a reel in a situation in which the annular protruding portion is protrudingly provided in the reel area.  
         [0025]    [0025]FIG. 5 is a perspective view showing a lower case of a conventional recording tape cartridge.  
         [0026]    [0026]FIG. 6 is a view showing a sectional view along the lines  6 - 6  in FIG. 5 and the positioning pins of the drive device. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    A recording tape cartridge  10  relating to an embodiment of the present invention will be described on the basis of FIGS.  1  to  3 . For convenience of explanation, a direction of loading the recording tape cartridge  10  into a drive device (the direction of an arrow A) is taken to be a forward direction, and the direction of an arrow B is taken to be a downward direction. Front, back, left, right, up and down are expressed with reference to a case of viewing in the direction of arrow A.  
         [0028]    As shown in FIG. 1, the recording tape cartridge  10  is structured to rotatably accommodate a single reel  14  in a case  16 . A magnetic tape  12 , which serves as a recording tape which is an information recording/replaying medium, is wound on the reel  14 . The case  16  is substantially rectangular in plan view.  
         [0029]    At the reel  14 , an upper flange  14 B and a lower flange  14 C are coaxially provided at respective upper and lower ends of a substantially cylindrical reel hub  14 A. The reel  14  is formed such that the reel hub  14 A, the upper flange  14 B and the lower flange  14 C are integrally rotatable. The magnetic tape  12  is wound around at an outer peripheral portion of the reel hub  14 A. A leader pin  18  is attached at a free end of the magnetic tape  12 , in a state in which both of end portions of the leader pin  18  protrude outward from width direction end portions of the magnetic tape  12 .  
         [0030]    The case  16  is formed in a substantially rectangular box shape by joining an upper case  20  and a lower case  22 , which are respectively formed of synthetic resin. A label area  38 , which is substantially rectangular in plan view, is recessedly provided at an upper face of the upper case  20 .  
         [0031]    A gear aperture portion  24  is formed at a substantially central portion of the lower case  22 . A reel rib  25  is standingly provided at an edge portion of the gear aperture portion  24 . The reel  14  is positioned by this reel rib  25 .  
         [0032]    A spring  68  is disposed in the case  16 . The spring  68  urges the reel  14  downward. As a result, an unillustrated reel gear provided downward of the reel  14  is exposed through the gear aperture portion  24 . An unillustrated gear meshes with the reel gear, and transmits rotary force to the reel  14 . Thus, the reel  14  is driven to rotate in the case  16 .  
         [0033]    Reel area ribs  62 , which are respectively circular arc-shaped, are standingly provided at inner faces of the upper case  20  and the lower case  22 . (In this respect, the upper case  20  is substantially the same as the lower case  22 , and thus illustration thereof is omitted.)  
         [0034]    The reel area ribs  62  are formed such that a radius of curvature thereof is slightly greater than an external radius of the upper flange  14 B and the lower flange  14 C of the reel  14 . Thus, the reel area ribs  62  demarcate a reel area  64  which rotatably accommodates the reel  14 .  
         [0035]    Further, a plurality of ribs  23  is provided between the reel area ribs  62  and peripheral walls of the upper case  20  and the lower case  22 . The ribs  23  connect the reel area ribs  62  with the respective outer walls, and reinforce the reel area ribs  62  and the outer walls.  
         [0036]    An annular protruding portion  66  (which is described later) is provided at the lower case  22 , at the reel area ribs  62  side of the reel area  64 . The annular protruding portion  66  forms a substantially rectangular shape in cross-section, and has a height substantially the same as the reel rib  25 .  
         [0037]    Substantially rectangular opening portions  26 A and  26 B are formed in a right side wall  20 A of the upper case  20  and a right side wall  22 A of the lower case  22 . An opening portion  26 , which is structured by the opening portion  26 A and the opening portion  26 B, is for drawing out the magnetic tape  12  from the case  16 . The opening portion  26  is opened and closed by a sliding door  28 .  
         [0038]    A pair of upper and lower rail grooves  30  are provided in the case  16  along the opening portion  26  (the rail groove in the upper case  20  is not shown). Specifically, in a state in which upper and lower end portions of the sliding door  28  are inserted into the rail grooves  30 , the sliding door  28  is structured to slide in the rail grooves  30 , to open and close the opening portion  26 . The sliding door  28  is urged forward by a coil spring  32 , so as to normally close up the opening portion  26 .  
         [0039]    Inward of the opening portion  26 , retaining channels  34  and  36  are provided in the upper case  20  and the lower case  22 , respectively. The upper and lower end portions of the leader pin  18  are inserted into the retaining channels  34  and  36 , and the leader pin  18  is retained at the retaining channels  34  and  36  by an unillustrated leaf spring or the like.  
         [0040]    The retaining channels  34  and  36  are formed so as to communicate with the rail grooves  30 . Side portions of the retaining channels  34  and  36  at vicinities thereof near the opening portion  26  are cut away so as to form portions of the rail grooves  30 .  
         [0041]    At an unillustrated library device which accommodates the recording tape cartridge  10 , a plurality of holders is provided. The recording tape cartridges  10  are loaded in the respective holders. When information is to be recorded/replayed, a desired one of the recording tape cartridges  10  is taken out by a robot hand or the like and loaded at one of drive devices (not shown).  
         [0042]    The recording tape cartridge  10  that has been loaded at the drive device is positioned in the drive device. In a state in which the recording tape cartridge  10  has been positioned thus, the magnetic tape  12  is drawn out from the case  16 , and information is recorded to the magnetic tape  12  and/or information that has been recorded at the magnetic tape  12  is replayed.  
         [0043]    As shown in FIG. 2 (note that the upper case  20  is not shown in this drawing), a first reference hole  50  and a second reference hole  58  are provided at a region of outer face of the lower case  22  which is obverse to (corresponds to) a region of the inner face that is located at an outer side of the reel area ribs  62 . In accordance with the first reference hole  50 , a boss  52  projects from the inner face of the lower case  22 . In accordance with the second reference hole  58 , a boss  60  projects from the inner face of the lower case  22  (refer to and compare with FIG. 1). Circular arc-shaped thickening portions  74  and  76  (which are described later) are protrudingly provided at base portions of the boss  52  and the boss  60 .  
         [0044]    The first reference hole  50  and the second reference hole  58  are fittable by insertion from outside of positioning pins  70  and  72 , which are disposed in the drive device, respectively. Thus, the first reference hole  50  and the second reference hole  58  serve as positioning references in horizontal directions (the front-rear direction and the left-right direction) of the recording tape cartridge  10  (see FIG. 1).  
         [0045]    Here, although the second reference hole  58  serves together with the first reference hole  50  as a positioning reference in the horizontal directions of the recording tape cartridge  10 , the second reference hole  58  is set to be a long hole in the left-right direction of the lower case  22 . Thus, an error in a separation distance between the first reference hole  50  and the second reference hole  58  can be tolerated.  
         [0046]    A first reference surface  78  and a second reference surface  80  are recessedly provided at opening portions of the first reference hole  50  and the second reference hole  58 , respectively. Pedestal seats  70 A and  72 A are provided at base portions of the positioning pins  70  and  72 , respectively. The first reference surface  78  and the second reference surface  80  are abuttable against the pedestal seats  70 A and  72 A.  
         [0047]    Accordingly, when the first reference hole  50  and the second reference hole  58  of the recording tape cartridge  10  are fitted over the drive device side positioning pins  70  and  72 , respectively, the first reference surface  78  formed at the first reference hole  50  and the second reference surface  80  formed at the second reference hole  58  abut against the pedestal seats  70 A and  72 A, respectively. Thus, the recording tape cartridge  10  is positioned in the horizontal directions and in the height direction.  
         [0048]    In accordance with the structure described above, when the magnetic tape  12  of the recording tape cartridge  10  shown in FIGS. 1 and 2 is to be used, the recording tape cartridge  10  is loaded along the direction of arrow A into a bucket of an unillustrated drive device. In accordance with this loading, the sliding door  28  is moved relatively in a direction opposite to the direction of arrow A, against urging force of the coil spring  32 , and the opening portion  26  is opened.  
         [0049]    In accordance with a descent of the bucket, the first reference hole  50  and the second reference hole  58  are fitted over the positioning pin  70  and the positioning pin  72 , respectively, of the drive device. Thus, positioning of the case  16  in the horizontal directions (the front-rear direction and the left-right direction) is achieved. Together therewith, the first reference surface  78  and the second reference surface  80  abut against the pedestal seats  70 A and  72 A of the positioning pins  70  and  72 , respectively. Thus, positioning of the case in the height direction is achieved.  
         [0050]    In this state, a hook member of the drive device engages with the two end portions of the leader pin  18  attached to the distal end of the magnetic tape  12 , which respectively protrude beyond the width direction end portions of the magnetic tape  12 . This hook member moves toward a take-up reel side of the drive device, and the two end portions of the leader pin  18  are accordingly taken out from the retaining channels  34  and  36 .  
         [0051]    Hence, the magnetic tape  12  is drawn out from the case  16  through the opening portion  26 , and is guided along a predetermined tape path to the take-up reel by the hook member. In this state, the reel  14  and the take-up reel are driven to rotate contemporaneously. Thus, the magnetic tape  12  is sequentially wound onto the take-up reel while reading of information (data) and/or replaying of information is carried out.  
         [0052]    When the magnetic tape  12  has been completely wound up by the take-up reel, the reel  14  and the take-up reel are driven to rotate in reverse, and the magnetic tape  12  is wound back to the reel  14 . When the magnetic tape  12  has been completely wound back onto the reel  14 , the leader pin  18  is put into the retaining channels  34  and  36  of the case  16 , and is retained by the unillustrated leaf spring.  
         [0053]    In this state, the bucket ascends, and the positioning pins  70  and  72  are removed from the first reference hole  50  and the second reference hole  58 , respectively. When the ascent of the bucket is complete, the recording tape cartridge  10  moves in the direction opposite to the direction of arrow A, the sliding door  28  closes the opening portion  26  due to the urging force of the coil spring  32 , and the recording tape cartridge  10  is ejected from the drive device. Thus, the recording tape cartridge  10  returns to its initial state.  
         [0054]    Next, the essence of a recording tape cartridge relating to an embodiment of the present invention will be explained.  
         [0055]    As shown in FIGS. 1 and 2, the annular protruding portion  66 , which forms an annular protruding surface, is protrudingly provided at the reel area ribs  62  side of the reel area  64  provided at the inner face of the lower case  22 . Further, the boss  52  and the boss  60  provided at the inner face of the lower case  22  are formed along an outer face of the reel area ribs  62 . Base portions of the bosses  52  and  60  are supported by parts of the annular protruding portion  66 , that is, the parts of the annular protruding portion  66  are formed to be extended beyond the reel area ribs  62  in certain places (i.e., the base portions of the bosses  52  and  60  are respectively located at such extended parts of the annular protruding portion  66 , that is, on the protruding surface).  
         [0056]    Accordingly, the thickening portions  74  and  76 , which are substantially the same height as the annular protruding portion  66 , are provided at the boss  52  and the boss  60 , respectively. Thicknesses at the first reference surface  78  and the second reference surface  80  are set to be substantially equal.  
         [0057]    Here, because the first reference surface  78  and the second reference surface  80  are recessedly provided at the region of the outer face of the lower case  22  that corresponds to the region at the outer side of the reel area ribs  62  formed on the inner face, thicknesses thereat would be made thinner in a situation in which the thickening portion  74 , the thickening portion  76  and the annular protruding portion  66  were not provided. However, because the thickening portion  74 , the thickening portion  76  and the annular protruding portion  66  are provided at the base portions of the bosses  52  and  60 , the thicknesses of the first reference surface  78  and the second reference surface  80  can be made thicker, and differences in thickness with respect to positions surrounding (peripheries of) the first reference surface  78  and the second reference surface  80 , that is, differences in thickness between positions at the first and the second reference surfaces  78 ,  80  and positions surrounding the first and the second reference surfaces  78 ,  80  can be made smaller.  
         [0058]    As a result, pressure variations at a time of forming can be made smaller, and post-formation sinking and/or flow lines and the like are less likely to occur around the first reference surface  78  and the second reference surface  80 . Moreover, high accuracy mold transcription for brightness and/or texturing can be obtained.  
         [0059]    Further, because the annular protruding portion  66  is protrudingly provided at the inner side of the reel area ribs  62 , resin can circulate more easily during formation of the reel area ribs  62 , and short shot of the reel area ribs  62  is less likely to occur.  
         [0060]    In addition, because the annular protruding portion  66  is protrudingly provided in the reel area  64 , stiffness of the lower case  22  can be increased. Thus, even if plate thickness in the reel area  64  is made the same as plate thickness of portions other than the reel area  64 , stiffness of the lower case  22  can be made sufficient in response to pressing force of the spring  68  disposed in the case  16 .  
         [0061]    Further again, when the recording tape cartridge  10  is not in use or the like, the reel  14  may become inclined in the recording tape cartridge  10 . At such a time, in a situation in which the annular protruding portion  66  is not provided in the reel area  64 , as shown in FIG. 4A, the reel  14  may be tilted to such an extent that the upper flange  14 B abuts against the inner face of the upper case  20  (an inclination of the reel  14  in this case is θ 1 ). However, because the annular protruding portion  66  whose internal diameter is smaller than the diameter of the lower flange  14 C is provided at the side of the reel area ribs  62 , as shown in FIG. 4B, an outer edge portion of the lower flange  14 C abuts against the annular protruding portion  66 , and tilting of the reel  14  is limited. Therefore, inclination of the reel  14  can be restrained (if an inclination of the reel  14  in this case is θ, then θ&lt;θ 1 ).  
         [0062]    The annular protruding portion  66 , which is protrudingly provided at the reel area ribs  62  side of the reel area  64 , has a substantially rectangular cross-sectional form. However, it is sufficient that pressure variations between the first reference surface  78  and second reference surface  80  and the surroundings of the first reference surface  78  and second reference surface  80  can be made smaller at the time of formation. Therefore, the cross-sectional form of the annular protruding portion is not limited thus.  
         [0063]    For example, as shown in FIG. 3, substantially truncated cone-shaped thickening portions  90 A and  92 A may be provided at base portions of bosses  90  and  92  in correspondence with a first reference surface  86  and a second reference surface  88 , respectively, and a sloping portion  98 , whose thickness gradually increases toward a base portion of a reel area rib  96 , may be provided in a reel area  94 .  
         [0064]    As shown in FIG. 1, the present embodiment has a structure which is provided with the leader pin  18 , which is held by the drive device side when the magnetic tape  12  is drawn out from the case  16 . However, the present invention is not limited thus. Obviously, the present invention can be applied to any recording tape cartridge provided with a member that can be held instead of the leader pin  18 . Thus, for example, the structure of the recording tape cartridge  10  may be provided with a leader block or a leader tape instead of the leader pin  18 .  
         [0065]    Further, in the present embodiment, an example in which the present invention is applied to the recording tape cartridge  10 , which rotatably accommodates the single reel  14  in the case  16 , has been illustrated. However, the present invention is not limited thus. For example, the present invention may be applied to a recording tape cartridge equipped with two reels for video use or the like.  
         [0066]    Further again, in this structure the magnetic tape  12  is used as the recording tape, but the present invention is not limited thus. It is sufficient if the recording tape is understood to be a long tape-like information recording/replaying medium which is capable of recording information and replaying information that has been recorded. The recording tape cartridge relating to the present invention can be applied to recording tape of any recording/replaying system.  
         [0067]    Because the present invention has the structure described above, rigidity of a case can be improved by protrudingly providing an annular protruding portion at an inner side of a reel area rib. Thickness differences between reference surfaces and reference surface peripheries can be made smaller by thickening, with the annular protruding portion and thickening portions, portions that would be thinner because of the reference surfaces. Thus, pressure variations during forming can be made smaller. Therefore, sinking after formation and/or flow lines and the like are less likely to occur at the reference surface peripheries, and/or high precision mold transcription for brightness and/or texturing can be obtained.  
         [0068]    Because the annular protruding portion is protrudingly provided at the inner side of the reel area rib, resin can circulate more easily (propagation is easier) when the reel area rib is formed, and short shot of the reel area rib is less likely to occur. Moreover, because the annular protruding portion is provided at the inner side of the reel area rib, if the reel is tilted when the recording tape cartridge is not in use or the like, then an outer edge portion of the reel abuts against the annular protruding portion. As a result, tilting of the reel can be suppressed.