Abstract:
A reel has: a hub which is cylindrical, which is molded of a resin material, and around which a recording tape is wound; and a flange provided at an end portion of the hub, and holding a transverse direction end portion of the recording tape. A ring-shaped member formed of metal is provided at the hub by insert molding. In accordance with the present invention, there is provided a reel in which can maintain a highly-accurate configuration of the hub, regardless of environmental changes.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a reel on which is wound a recording tape, such as a magnetic tape or the like, used for storing data of a computer or the like.  
           [0003]    2. Description of the Related Art  
           [0004]    Conventionally, among recording tape cartridges used as recording media used in external storage devices of computers and the like, there is a type in which a single reel, on which a recording tape such as a magnetic tape or the like is wound, is rotatably accommodated within a recording tape cartridge. The magnetic tape is used for storing data of a computer or the like, and important information is recorded thereon. Thus, the recording tape cartridge is structured such that the magnetic tape cannot be inadvertently pulled out therefrom when the recording tape cartridge is not being used (such as when the recording tape cartridge is being stored or the like), and also, so that trouble such as jamming of the tape or the like will not occur.  
           [0005]    Recently, the storage capacity of recording tape cartridges has increased and, as a result, the amount of data which can be recorded has increased from several tens of GBs to several hundreds of GBs. In order to realize such an increase in storage capacity, the track pitch width has been decreased, or the thickness of the magnetic tape has been decreased. Accordingly, high dimensional accuracy is required of the recording tape cartridge itself as well. In particular, the dimensions and the configuration of the reel on which the magnetic tape is wound must be highly accurate.  
           [0006]    However, at a reel, both the cylindrical hub on which the magnetic tape is wound, and the upper and lower flanges which are provided at the upper and lower end portions of the hub and which hold the transverse direction end portions of the magnetic tape wound around the hub, are molded of a resin material. Thus, there are cases in which slight deformation occurs due to changes in temperature and/or humidity at the time when the recording tape cartridge is being transported. When such deformation arises at the hub in particular, a problem arises in that a fair amount of the magnetic tape is adversely affected thereby, i.e., bending or the like due to this deformation arises at the magnetic tape itself.  
         SUMMARY OF THE INVENTION  
         [0007]    In view of the aforementioned, an object of the present invention is to provide a reel in which the high accuracy of the dimensions and the configuration of a hub can be maintained, regardless of changes in the environment such as the temperature, the humidity, or the like.  
           [0008]    In order to achieve the above object, a reel relating to the present invention comprises: a hub which is cylindrical, which is molded of a resin material, and around which a recording tape is wound; and a flange provided at an end portion of the hub, and holding a transverse direction end portion of the recording tape, wherein a ring-shaped member formed of metal is provided at the hub by insert molding.  
           [0009]    In accordance therewith, even if the hub, which is formed of resin, attempts to deform due to changes in the environment such as the temperature, the humidity or the like, such deformation is suppressed by the ring-shaped member which is formed of metal and provided at the hub by insert molding. Further, similarly, even if the recording tape contracts in the winding/tightening direction (the radial direction of the hub) due to changes in the environment such as the temperature, the humidity or the like, deformation due to such contraction is suppressed because the strength of the hub is improved by the ring-shaped member formed of metal. Accordingly, it is possible to obtain a hub whose dimensional accuracy can be maintained high, and a recording tape wound thereon is not adversely affected. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is an exploded perspective view of a magnetic tape cartridge having a reel relating to the present invention.  
         [0011]    [0011]FIG. 2 is a perspective view, as seen from below, of the reel relating to the present invention, a braking member, and an upper case.  
         [0012]    [0012]FIG. 3 is a side sectional view of a driving device and the magnetic tape cartridge which has the reel relating to the present invention.  
         [0013]    [0013]FIG. 4 is an exploded side sectional view of the reel relating to the present invention.  
         [0014]    [0014]FIG. 5 is a schematic side sectional view showing a mold for molding a reel hub and a lower flange of the reel relating to the present invention.  
         [0015]    [0015]FIG. 6A is a schematic side sectional view showing a modified example of the reel relating to the present invention.  
         [0016]    [0016]FIG. 6B is a schematic side sectional view showing another modified example of the reel relating to the present invention.  
         [0017]    [0017]FIG. 7A is a schematic side sectional view showing main portions of a mold for molding the reel of FIG. 6A.  
         [0018]    [0018]FIG. 7B is a schematic side sectional view showing main portions of a mold for molding the reel of FIG. 6B. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]    Hereinafter, a reel relating to an embodiment of the present invention will be described on the basis of the drawings. Note that the reel relating to the present invention may be applied to a one-reel-type recording tape cartridge in which a single reel is accommodated within a case, or to a two-reel-type recording tape cartridge in which a pair of reels are accommodated within a case. Here, explanation will be given by using, as an example, a one-reel-type recording tape cartridge. Moreover, for convenience of explanation, the direction of loading the recording tape cartridge into a drive device is called the forward direction, and the front-back, left-right, and top-bottom directions are expressed on the basis of this forward direction. Further, a magnetic tape is used as the recording tape, and hereinafter, explanation will be given of a magnetic tape cartridge  10 .  
         [0020]    First, the overall structure of the magnetic tape cartridge  10  will be described. As shown in FIGS. 1 through 3, the magnetic tape cartridge  10  has an upper case  20  and a lower case  30  which are formed of a synthetic resin. The magnetic tape cartridge  10  is formed in a substantially rectangular box shape by peripheral walls  22 ,  32  of the upper case  20  and the lower case  30  being welded together by ultrasonic welding or the like. Play restricting walls  24 ,  34  stand erect at the inner surfaces of the upper case  20  and the lower case  30 , respectively. The inner diameters of the play restricting walls  24 ,  34  are formed to be slightly larger than the outer diameters of an upper flange  52  and a lower flange  54  of a reel  50 . The reel  50  is rotatably accommodated at the inner sides of the play restricting walls  24 ,  34 .  
         [0021]    A plurality of ribs  23  are provided between the play restricting wall  24  and the peripheral wall  22  of the upper case  20 . A plurality of ribs  33  are provided between the play restricting wall  34  and the peripheral wall  32  of the lower case  30 . The play restricting wall  24  and the peripheral wall  22  are connected by the ribs  23 , and the play restricting wall  34  and the peripheral wall  32  are connected by the ribs  33 . The play restricting walls  24 ,  34  and the peripheral walls  22 ,  32  are thereby strengthened.  
         [0022]    The reel  50  is structured by a reel hub  56  which is cylindrical and formed of a synthetic resin, and the upper flange  52  and the lower flange  54  which are provided at the end portions of the reel hub  56 . The widthwise direction end portions of a magnetic tape  12 , which serves as an information recording/playback medium wound on the reel hub  56 , are held at the upper flange  52  and the lower flange  54 .  
         [0023]    A bottom wall  58  is provided at the lower flange  54  of the reel hub  56 . A hole portion  58 A is formed in the center of the bottom wall  58 . An annular reel gear  60  projects out from the bottom wall  58  at the bottom surface side of the bottom wall  58 . The reel gear  60  can emerge from a circular open hole  38  provided at the center of the lower case  30 , and meshes with a driving gear  62  provided at a drive device  68  so as to transmit rotational force to the reel  50 .  
         [0024]    An annular metal plate  48  is provided integrally with the inner side of the reel gear  60 . Due to the metal plate  48  being attracted by a magnet (not shown) provided at the drive device  68 , axial offset is prevented, and the meshed-together state of the reel gear  60  and the driving gear  62  can be maintained. On the other hand, an annular groove  46  is provided at the outer side of the reel gear  60 . The reel  50  is positioned with respect to the lower case  30  due to a rib  36 , which stands erect at the peripheral edge portion of the open hole  38 , being inserted into the annular groove  46 .  
         [0025]    Further, an annular reel gear  70  is formed at the top surface side of the bottom wall  58  of the reel hub  56 . The reel gear  70  can mesh with a braking gear  82  which is formed at the outer peripheral portion of the bottom surface of a substantially disc-shaped braking member  80  which can be accommodated within the reel hub  56 . Ribs  84 , which are substantially U-shaped as seen in plan view (and are referred to hereinafter as “U-shaped ribs”), stand erect at the top surface of the braking member  80  such that the open sides thereof oppose each other. On the other hand, a pair of anchor pins  26  are provided vertically at the center of the inner surface of the upper case  20 , and can engage with the U-shaped ribs  84 .  
         [0026]    An annular groove  86  is provided at the outer side of the U-shaped ribs  84  of the braking member  80 . An annular projection  28  projects at the outer side of the anchor pins  26  of the upper case  20 . A spring  16  is provided between the braking member  80  and the upper case  20  by being held between the annular projection  28  and the annular groove  86 .  
         [0027]    Accordingly, when the magnetic tape cartridge  10  is not being used, the anchor pins  26  are inserted into the U-shaped ribs  84 , such that rotation of the braking member  80  is impeded. The braking gear  82  of the braking member  80  whose rotation has been impeded is urged toward the reel gear  70 , and strongly meshes with the reel gear  70  within the reel hub  56 . In this way, inadvertent rotation of the reel  50  is prevented.  
         [0028]    On the other hand, a projection  88 , which is substantially solid-cylindrical and which can be inserted through the hole portion  58 A, projects at the center of the bottom surface of the braking member  80 . Before the reel gear  60  meshes with the driving gear  62  and rotational force is transmitted to the reel  50 , a meshing releasing pin  64 , which is provided at the distal end portion of a rotating shaft  66  provided at the drive device  68 , abuts the projection  88 . The braking member  80  is thereby pushed upward against the urging force of the spring  16 , and the meshing of the braking gear  82  and the reel gear  70  is released. In this way, the reel  50  is able to rotate.  
         [0029]    Further, a leader block  40  is attached to the distal end portion of the magnetic tape  12  due to an elastic pin  14  and the distal end of the magnetic tape  12  being fit into a concave portion  42  of the leader block  40 . Opening portions  18 ,  19  are formed at the front right corner portions of the peripheral wall  22  of the upper case  20  and the peripheral wall  32  of the lower case  30 , respectively.  
         [0030]    The opening portions  18 ,  19  are for enabling the magnetic tape  12 , which is wound on the reel  50 , to be pulled out to the exterior. An unillustrated pull-out pin provided at the drive device engages with an engagement portion  44  formed at the distal end of the leader block  40 , and pulls the leader block  40  out from the opening portions  18 ,  19 , and fits the leader block  40  in a take-up reel (not shown) provided at the drive device.  
         [0031]    Thereafter, by driving the reel  50  and the take-up reel to rotate synchronously, data is recorded onto the magnetic tape  12  or data recorded on the magnetic tape  12  is played back, while the magnetic tape  12  is successively taken-up onto the take-up reel. Further, when the magnetic tape cartridge  10  is not being used, the leader block  40  is anchored on the peripheral edges of the opening portions  18 ,  19  and closes the opening portions  18 ,  19 .  
         [0032]    Next, the reel  50  relating to the present invention will be described in detail. Note that repeat explanation will not be given of portions which have been described above. As shown in FIGS. 3 and 4, the reel hub  56  and the lower flange  54 , which structure the reel  50 , are molded integrally of a resin material. A welding material (portion)  72  for ultrasonic welding, which is substantially triangular in cross-section, projects at the distal end surface (the top surface) of the reel hub  56 . The upper flange  52  is placed on the peak portion of this welding material  72 , and in this state, by melting the welding material  72  by ultrasonic waves, the upper flange  52  is welded onto the distal end surface (top surface) of the reel hub  56  such that the reel  50  is formed.  
         [0033]    The reel hub  56  and the upper flange  52  are molded by using resin materials which are compatible with one another. In this way, the reel hub  56  and the upper flange  52  can be welded together by ultrasonic waves. Examples of the types of resin materials are combinations such as PMMA and ABS, AS and ABS, PC and PC, and the like.  
         [0034]    As described above, the metal plate  48  is provided at the inner side of the reel gear  60 . As shown in FIG. 5, the metal plate  48  is inserted and integrally molded in a mold  90  which molds the reel hub  56  and the lower flange  54 . A fixed side mold plate  92  and a movable side mold plate  94  are provided at the mold  90 . In the state in which the metal plate  48  is fixed to the fixed side moldplate  92 , the mold  90  is clamped, and a molding material (resin material) is filled into a cavity  98  formed by the fixed side mold plate  92  and the movable side mold plate  94 .  
         [0035]    Here, an annular concave portion  47  is provided in one end side (the bottom surface side) of the metal plate  48 . When the metal plate  48  is set at the fixed side mold plate  92 , the annular concave portion  47  fits with an annular convex portion  96  formed at the fixed side mold plate  92 , and the metal plate  48  is positioned and fixed at the fixed side mold plate  92 . Further, an annular taper portion  49  serving as a bitten-in portion is provided at the peripheral edge portion of one end side (the lower surface side) of the metal plate  48 .  
         [0036]    In the state in which the metal plate  48  is set at the fixed side metal plate  92 , there is a gap between the taper portion  49  of the metal plate  48  and the fixed side mold plate  92 . At the time of molding, due to the molding material (resin material) flowing into this gap, an annular claw portion  59 , which serves as a biting-in portion which bites into the outer peripheral edge of the metal plate  48 , is formed at the reel hub  56 .  
         [0037]    Due to the claw portion  59  biting into the taper portion  49  of the metal plate  48 , the metal plate  48  becomes integral with the reel hub  56  and the lower flange  54 . However, provided that there is a structure in which the metal plate  48 , the reel hub  56 , and the lower flange  54  can be made integral by insert molding, any structure suffices, and the present invention is not limited to the illustrated structure.  
         [0038]    Further, a ring-shaped member  74  formed of metal (and hereinafter called “metal ring”) is provided integrally by insert molding at the inner side of the reel hub  56 . The material of the metal ring  74  can be appropriately selected in accordance with the resin material used for the reel hub  56  and the configuration (such as the thickness and the like) of the reel hub  56 . However, a non-magnetic stainless material is particularly preferable.  
         [0039]    The outer peripheral surface of the metal ring  74  is a roughened surface or a knurled surface in which the resin material can get caught. As shown in FIG. 5, after fitting the metal ring  74  in the movable side mold plate  94 , the mold  90  is clamped, and the molding material (resin material) is filled into the cavity  98 . In this way, the outer peripheral surface of the metal ring  74  and the inner peripheral surface of the reel hub  56  can be adhered together.  
         [0040]    Note that, at the time of fitting the metal ring  74  into the movable side mold plate  94 , a gap S is formed between the movable side mold plate  94  and the inner peripheral edge of the bottom end side of the metal ring  74 . At the time of molding, due to the molding material (resin material) flowing into the gap S, an annular claw portion  76 , which tightly contacts the inner peripheral edge of the bottom end side of the metal ring  74 , is formed. In this way, the metal ring  74  is mounted even more stably to the reel hub  56 .  
         [0041]    In this way, in the same way as the above-described metal plate  48 , the metal ring  74  is provided integrally with the reel hub  56 . Due to the outer peripheral surface of the metal ring  74 , which is shown in FIGS. 3 through 5, being adhered to the inner peripheral surface of the reel hub  56 , the inner peripheral surface of the metal ring  74  is exposed at the inner side of the reel hub  56 . Accordingly, it is preferable that the inner peripheral surface of the metal ring  74  in this case be formed as a smooth surface.  
         [0042]    Further, the distal end surface (top surface) of the metal ring  74  is formed to a height which reaches a position which is a predetermined length lower than the distal end surface (top surface) of the reel hub  56 . A boss  52 A of the same height as this predetermined length is formed at the bottom surface of the upper flange  52 . When the upper flange  52  is placed on the peak portion of the welding material  72 , the boss  52 A engages (contacts) the inner peripheral surface of the reel hub  56 . Accordingly, in this state, when the upper flange  52  is welded to the distal end surface (top surface) of the reel hub  56  by ultrasonic welding, the distal end surface (bottom surface) of the boss  52 A and the distal end surface (top surface) of the metal ring  74  abut one another, and the reel  50  which has high dimensional accuracy is obtained.  
         [0043]    Further, it is possible to, rather than carrying out insert molding such that the metal ring  74  is exposed to the inner side of the reel hub  56 , carry out insert molding such that the metal ring  74  is embedded within the reel hub  56  as shown in FIGS. 6A and 6B. In this case, at least one of the outer peripheral surface and the inner peripheral surface of the metal ring  74  is made to be a roughened surface or a knurled surface, and as shown in FIGS. 7A and 7B, an annular concave portion  78 , which holds the upper end portion of the metal ring  74 , is provided in the movable side mold plate  94 . In this structure, the metal ring  74  can be positioned and fixed so that the metal ring  74  is stable at the time of molding.  
         [0044]    By using such a structure, a reel hub  56  in which the metal ring  74  is embedded in a substantially central portion in the direction of thickness thereof is molded. Further, at the upper portion thereof, either the distal end surface (top surface) of the outer side of the reel hub  56  and the distal end surface (top surface) of the metal ring  74  are molded to the same height as shown in FIG. 6A, or the distal end surface (top surface) of the metal ring  74  projects out slightly from the distal end surface (top surface) of the reel hub  56  as shown in FIG. 6B. Note that, in both cases, the configurations and the like of the upper flange  52  and the boss  52 A can of course be changed appropriately.  
         [0045]    In any case, when the metal ring  74  and the reel hub  56  are provided integrally, the strength of the reel hub  56  can be improved. Namely, as compared with resin, metal has a lower coefficient of linear expansion and hardly deforms at all. Thus, even if, due to changes in the environment such as the temperature or the humidity or the like, the resin reel hub  56  attempts to deform itself, or the magnetic tape  12  contracts in the winding/tightening direction and attempts to deform the reel hub  56 , deformation of the reel hub  56  can be suppressed by the metal ring  74  which is molded integrally with the reel hub  56 .  
         [0046]    Accordingly, the reel hub  56  which has high dimensional accuracy can be obtained, and the magnetic tape  12  wound therearound is not adversely affected. Moreover, the metal ring  74  is exposed to the inner side of the reel hub  56 , or is provided so as to be embedded in the substantially central portion in the direction of thickness of the reel hub  56 . Thus, when the temperature is high, if it takes a relatively long time for the temperature of the metal ring  74  to fall, the magnetic tape  12  is not adversely affected.  
         [0047]    As described above, in accordance with the present invention, the strength of the hub can be increased and deformation thereof can be suppressed by the ring-shaped member formed of metal which is provided at the hub by insert molding. Accordingly, a hub having high dimensional accuracy can be obtained, and the recording tape wound therearound is not adversely affected.