Patent Publication Number: US-2009218430-A1

Title: Reel and recording tape cartridge

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC 119 from Japanese Patent Application No. 2008-049386, the disclosure of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a reel around which a recording tape such as a magnetic tape is wound and a recording tape cartridge provided with the reel. 
     2. Description of the Related Art 
     There is well known a technique in which rigidity of a resin made reel hub is ensured by mounting a ring-shaped reinforcing member on an opening end side of the reel hub (for example, see Japanese patent Application Laid-Open Nos. 2004-127358 and 2005-182948). 
     However, in a structure of the conventional technique mentioned above, a flange on the opening end side of the reel hub is formed separately from the reel hub, and a flange on a bottom portion side of the reel hub is integral with the reel hub. In other words, there is a large difference in rigidity between both ends in an axis line direction of the reel hub in the case where the reinforcing member is not provided. Therefore, it is necessary that a high-rigidity reinforcing ring be used to reduce the difference in rigidity, and unfortunately there are many restrictions in a material, dimensions, and shape of the reinforcing member (low degree of freedom of design). 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, an object of the present invention is to provide a reel which substantially equalizes the rigidity at both ends in the axis line direction of the reel hub using a small and light-weight reinforcing ring and a recording tape cartridge which applies the reel to well protect the recording tape. 
     In accordance with a first aspect of the present invention, a reel includes: a reel hub that is made of a resin material and is formed into a cylindrical shape having a bottom portion; a flange that is made of a resin material and is provided integrally at the reel hub so as to extend outwardly in a radial direction of the reel hub from an opening end of the reel hub; a flange member that is made of a resin material and is bonded to an end portion on the bottom portion of the reel hub, the flange member having a flange portion facing the flange; and a reinforcing ring that reinforces the reel hub in the radial direction and is attached to a part of the reel hub in an axis line direction of the reel hub, the part including the opening end. 
     In the reel according to the first aspect of the invention, the flange member is bonded to the end portion of the bottom portion of the reel hub, and the flange portion of the flange member faces the flange extended from the opening end of the reel hub. Usually, compared with the bottom portion side of the reel hub, the radial rigidity tends to be decreased at the opening end side of the reel hub. However, in the reel according to the first aspect, the flange member is formed separately from the reel hub in order to suppress the increase in rigidity of the reel hub at the bottom portion side, and the rigidity is increased at the opening end side of the reel hub by the reinforcing ring and the flange integrally extended from the opening end. Therefore, the difference in rigidity is decreased at both ends in the axis line direction of the reel hub. In the configuration of the first aspect, it is only necessary to attach the reinforcing ring to a part of the reel hub in the axis line direction of the reel hub. The part of the reel hub includes the opening end in the reel hub. 
     Thus, in the reel according to the first aspect, the rigidity can substantially be equalized at both ends in the axis line direction of the reel hub by using the small and light-weight reinforcing ring. Therefore, in the reel hub, deformation amounts are substantially equalized at both the ends in the axis line direction in the state in which the reel hub is deformed by a winding pressure of the wound subject. 
     In accordance with a second aspect of the present invention, a reel includes: a reel hub that is made of a resin material and is formed into a cylindrical shape having a bottom portion; a flange that is made of a resin material and is provided integrally at the reel hub so as to extend outwardly in a radial direction of the reel hub from an opening end of the reel hub; a flange member that is made of a resin material and is bonded to the bottom portion of the reel hub within a range where a metal plate attached to a center portion of the flange member overlaps the bottom portion of the reel hub in an axis line direction of the reel hub, the flange member having a flange portion facing the flange; and a reinforcing ring that reinforces the reel hub in the radial direction and is attached to a part of the reel hub in the axis line direction, the part including the opening end. 
     In the reel according to the second aspect, the center portion of the flange member is bonded to the bottom portion of the reel hub, and the flange portion of the flange member faces the flange extended from the opening end of the reel hub. Usually, compared with the bottom portion which is of the closed end of the reel hub, the radial rigidity tends to be decreased at the opening end of the reel hub. However, in the reel of the second aspect, the flange member is formed separately from the reel hub in order to suppress the increase in rigidity of the reel hub at the bottom portion side, the rigidity is increased at the opening end side of the reel hub by the reinforcing ring and the flange integrally extended from the opening end. Therefore, the difference in rigidity is decreased at both the ends in the axis line direction of the reel hub. In the configuration of the second aspect, it is only necessary to attach the reinforcing ring to a part of the reel hub in the axis line direction of the reel hub. The part of the reel hub includes the opening end of the reel hub. 
     Thus, in the reel according to the second aspect, the difference in rigidity at both the ends in the axis line direction of the reel hub can be equalized by using the small and light-weight reinforcing ring. Therefore, in the reel hub, deformation amounts are substantially equalized at both the ends in the axis line direction in the state in which the reel hub is deformed by a winding pressure of the wound subject. In the flange member bonded to the bottom portion of the reel hub in the center portion where the metal plate is attached, the flange portion is hardly deformed due to the deformation of the reel hub. 
     In accordance with a third aspect of the present invention, in the reel according to the first or second aspect, the reinforcing ring is attached to the reel hub such that a clearance is radially formed between the reinforcing ring and an inner circumference of the reel hub. 
     In the reel according to the third aspect, because the clearance is radially set between the reel hub and the reinforcing ring, in other words, because the reinforcing member is attached to the reel hub by loose fitting, accuracy of the winding surface of the reel hub is not influenced by attaching the reinforcing ring. Additionally the reinforcing ring is easily attached. 
     In accordance with a fourth aspect of the present invention, in the reel as in any one of first to third aspects, a clearance of 0.05 mm or less is set between the inner circumference of the reel hub and an outer circumference of the reinforcing ring. 
     In the reel according to the fourth aspect, the clearance of 0.05 mm or less is set between the inner circumference of the reel hub and the outer circumference of the reinforcing ring. Therefore, the good reinforcing effect of the reel hub is exerted by the reinforcing ring in a creep environment of the resin reel hub. 
     In accordance with a fifth aspect of the present invention, in the reel as in any one of first to fourth aspects, the reinforcing ring is fixed to the reel hub by welding. 
     In the reel according to the fifth aspect, the reinforcing ring which is formed separately from the reel hub is fixed to the reel hub by the welding. Therefore, the reinforcing ring has no influence on resin molding of the reel hub and the flange. 
     In accordance with a sixth aspect of the present invention, in the reel according to the fifth aspect, the reinforcing ring is fixed to the reel hub by welding in a face portion orientated toward the axis line direction of the reel hub. 
     In the sixth aspect, it is possible that the reinforcing ring includes an outer flange portion provided so as to extend outwardly in the radial direction, a step portion at which the face portion is formed is formed at the opening end of the reel hub, and a lower face of the outer flange portion is fixed to the face portion by welding. 
     In the reel according to the sixth aspect, the reinforcing ring is fixed to the reel hub at the face portion (including surface inclined to the surface orthogonal to the axis line direction of the reel hub) orientated toward the axis line direction of the reel hub. Therefore, the reinforcing ring can be fixed to the reel hub while the clearance is radially formed between the reinforcing ring and the reel hub. 
     In accordance with a seventh aspect of the present invention, the recording tape cartridge includes a case; and the reel as in any one of first to sixth aspects in which a recording tape is wound around a winding surface of the reel hub, the recording tape being accommodated in the case while being able to be drawn and wound. 
     In the recording tape cartridge according to the seventh aspect, the recording tape wound around the reel hub of the reel is drawn from the case to write and read (may be either one) information. Applying of the reel as in any one of first to sixth aspects equalizes the rigidity at both the ends in the axis line direction of the reel hub. In the state in which the recording tape is wound around the reel hub, the shape of the reel hub substantially becomes symmetrical in relation to the center in the axis line direction, thereby suppressing the deformation of the recording tape wound around the reel hub. That is, the recording tape is protected. 
     Thus, in the recording tape cartridge according to the seventh aspect, the recording tape may well be protected by applying the reel of any one of the aspects. 
     In accordance with an eighth aspect of the present invention, preferably the recording tape cartridge according to the seventh aspect further includes a rotation lock member that is provided in the reel hub so as to be able to be relatively displaced in the axis line direction of the reel hub with respect to the case, the rotation lock member being switched between a rotation lock position and a rotation permission position by the relative displacement, rotation of the reel with respect to the case being prohibited at the rotation lock position and rotation of the reel with respect to the case being permitted at the rotation permission position, wherein the reinforcing ring is formed such that a gap in the radial direction between the reinforcing ring and the rotation lock member when the rotation lock member is located at the rotation lock position becomes a predetermined value or less. 
     In the recording tape cartridge according to the eighth aspect, the reel is prohibited to be rotated with respect to the case by the rotating lock member located at the rotating lock position. In the rotating lock state, the reinforcing ring attached to the reel hub faces the rotating lock member from the radial outside with the gap of the predetermined value or less. Therefore, the radial position shift of the rotating lock member relative to the reel, that is, the radial position shift of the reel relative to the case is suppressed. 
     Thus, the reel of the invention has the excellent effect that the reel can ensure a proper attitude of the flange with respect to the reel hub. Additionally the recording tape cartridge of the invention has the excellent effect that the recording tape can well be protected by applying this reel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will be described in detail with reference to the following figures, wherein: 
         FIG. 1  is an enlarged sectional view showing a main part of a reel according to an exemplary embodiment of the invention; 
         FIG. 2  is an exploded perspective view showing the reel according to the exemplary embodiment of the invention; 
         FIG. 3  is a perspective view showing the reel according to the exemplary embodiment of the invention; 
         FIGS. 4A and 4B  show an appearance of a recording tape cartridge to which the reel according to the exemplary embodiment of the invention is applied,  FIG. 4A  is a perspective view of the recording tape cartridge when the recording tape cartridge is viewed from above, and  FIG. 4B  is a perspective view of the recording tape cartridge when the recording tape cartridge is viewed from below; 
         FIG. 5  is a sectional view showing the recording tape cartridge to which the reel according to the exemplary embodiment of the invention is applied in rotary lock of the reel; 
         FIG. 6  is a sectional view showing the recording tape cartridge to which the reel according to the exemplary embodiment of the invention is applied in releasing the rotary lock of the reel; and 
         FIGS. 7A to 7C  are enlarged views showing reels according to comparative examples with respect to the exemplary embodiment of the invention,  FIG. 7A  is a sectional view of a first comparative example,  FIG. 7B  is a sectional view of a second comparative example, and  FIG. 7C  is a sectional view of a third comparative example. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A reel  28  according to an exemplary embodiment of the present invention and a recording tape cartridge  10  to which the reel  28  is applied will be described with reference to  FIGS. 1 to 6 . An entire configuration of the recording tape cartridge  10  will schematically be described first and a configuration of the reel  28  will be described in detail next. 
       FIG. 4A  is a perspective view of the recording tape cartridge  10  when the recording tape cartridge  10  is viewed obliquely from above, and  FIG. 4B  is a perspective view of the recording tape cartridge  10  when the recording tape cartridge  10  is viewed obliquely from below.  FIG. 5  is a sectional view taken on a line  5 - 5  of  FIG. 4A . An arrow A of  FIG. 4  indicates a direction in which the recording tape cartridge  10  is loaded in a drive device. For the sake of convenience, in the following description, a side indicated by the arrow A is referred to as a front side, and a side indicated by an arrow U is referred to as an upper side. 
     As shown in  FIGS. 4 and 5 , the recording tape cartridge  10  includes a case  12 . The case  12  is formed by bonding an upper case  14  and a lower case  16 . Specifically the upper case  14  is formed while a substantially frame-shaped peripheral wall  14 B is vertically provided along an outer edge of a top plate  14 A having a rectangular shape in planar view, and a lower case  16  is formed while a peripheral wall  16 B is vertically provided along an outer edge of a bottom plate  16 A having a shape substantially corresponding to the top plate  14 A. In the case  12 , the upper case  14  and the lower case  16  are bonded and formed into a substantial box shape by ultrasonic welding or screws while an opening end of the peripheral wall  14 B and an opening end of the peripheral wall  16 B abut on each other. 
     In the case  12 , the top plate  14 A, the peripheral wall  14 B, the bottom plate  16 A, and the peripheral wall  16 B are notched in a corner portion on a head side in the direction in which the recording tape cartridge  10  is loaded in the drive device, and thereby forming an opening  18  which is inclined relative to the loaded direction. A circular gear opening  20  which is pierced through the bottom plate  16 A is provided in a substantial center portion of the bottom plate  16 A, and the gear opening  20  is used to expose a reel gear  62  described later. In an edge portion of the gear opening  20  in the bottom plate  16 A, an annular rib  22  is projected toward the inside of the case  12  (see  FIG. 5 ), and the rib  22  is used for positioning of a reel  28  described later. 
     A pair of positioning holes  24  and  26  is opened near a front end in an outer surface of the bottom plate  16 A of the case  12 . The pair of positioning holes  24  and  26  is made in a pouched shape in a projected portion (not shown) vertically provided from the bottom plate  16 A toward the inside of the case  12 , and the positioning holes  24  and  26  are disposed while separated from each other on a virtual line orthogonal to the loaded direction. The positioning hole  24  located closer to the opening  18  is formed into a substantially square shape in bottom view, and the positioning hole  24  is circumscribed in a positioning pin of the drive device. The positioning hole  26  is formed into a long hole along the virtual line, and a width of the positioning hole  26  corresponds to a diameter of the positioning pin. Therefore, when the recording tape cartridge  10  is loaded in the drive device to insert the positioning pins into the positioning holes  24  and  26 , the recording tape cartridge  10  is correctly positioned in a horizontal direction (right and left, back and forth) in the drive device. 
     Portions around the positioning holes  24  and  26  in the bottom plate  16 A are formed into positioning surfaces  24 A and  26 A which are finished smoother than other portions (design surface). The positioning surfaces  24 A and  26 A abut on positioning surfaces of the drive device provided around the positioning pins when the positioning pins are inserted into the positioning holes  24  and  26 . Therefore, the positioning in the vertical direction is also performed in the drive device of the recording tape cartridge  10 . 
     As shown in  FIG. 5 , a reel  28  is rotatably accommodated in the above mentioned case  12 . Only one reel  28  is provided. A magnetic tape T which is of the recording tape is wound around the reel  28 , and a leader block  30  which is of a drawing member is attached to a leading end of the magnetic tape T. 
     The leader block  30  is accommodated and retained inside the opening  18  of the case  12  when the recording tape cartridge  10  is not used. At this state, the leader block  30  closes the opening  18  to prevent dust from invading into case  12 . An engagement recess  30 A is formed at a leading end of the leader block  30 . When the magnetic tape T is drawn in the drive device, the magnetic tape T is drawn from the case  12  by a drawing unit engaged with the engagement recess  30 A, and the magnetic tape T is guided to the winding reel of the drive device. In the leader block  30 , an end face on the opposite side to the engagement recess  30 A is formed into an arc surface  30 B, and the arc surface  30 B is fitted in the winding reel to partially constitute the winding surface which winds the magnetic tape T. 
     The recording tape cartridge  10  includes a brake member  32  which is of the rotary lock member to prevent the rotation of the reel  28  when the recording tape cartridge  10  is not used. The brake member  32  mainly includes a disc portion  34 , a braking gear  36 , a cross projection  38 , and a sliding contact projection  35 . The disc portion  34  is formed into a disc shape. The braking gear  36  is formed downward in a peripheral portion of the disc portion  34 . The cross projection  38  is projected upward from a axis center portion of the disc portion  34 . The sliding contact projection  35  is projected downward from the axis center portion of the disc portion  34 . An insertion groove  38 A is formed in the cross projection  38 , and the insertion groove  38 A corresponding to the shape of the cross projection  38  is formed into a substantially cross shape in a planar view. A cross rib  40  hanging from the top plate  14 A is inserted into the insertion groove  38 A while being relatively movable (slidable) in a vertical direction. Therefore, the brake member  32  may not be rotated with respect to the case  12 , and the brake member  32  may relatively be displaced in the vertical direction with respect to the case  12 . 
     The braking gear  36  of the brake member  32  is engaged with an engagement gear  52  (described later) projected upward from a bottom plate  48  constituting the reel  28 , thereby preventing the rotation of the reel  28  with respect to the case  12 . The braking gear  36  is moved with respect to the case  12  in the vertical direction (the axis line direction of the reel  28 ), thereby switching between the engagement of the braking gear  36  with the engagement gear  52  (rotary lock position) and the engagement release (rotary permission position). A compression coil spring  42  is provided in the recording tape cartridge  10  to bias the brake member  32  toward the side of the bottom plate  48 , and the braking gear  36  of the brake member  32  is biased toward a braking position at which the braking gear  36  is engaged with the engagement gear  52 . 
     The recording tape cartridge  10  includes a release pad  44  which is of a release member. The release pad  44  releases the rotary lock state in which the brake member  32  locks the reel  28  with respect to the case  12 . The release pad  44  includes a plate-like main body portion  44 A having a substantially equilateral triangle shape in planar view and leg portions  44 B projected downward from tops of the main body portion  44 A. In the release pad  44 , the plate-like main body portion  44 A is pressed against the sliding contact projection  35  of the brake member  32  whose braking gear  36  is engaged with the engagement gear  52 , and each leg portion  44 B is pierced through a unlock hole (lock release hole)  64  formed in the bottom plate  48  of the reel  28 . The portion projected toward the outside (lower side) of the reel  28  in each leg portion  44 B is pressed upward, whereby the brake member  32  is moved upward along with the release pad  44  to the rotary permission position at which the engagement is released between the braking gear  36  and the engagement gear  52 . 
     In the exemplary embodiment, the leg portion  44 B of the release pad  44  is pressed upward by a drive gear  106  of the rotary shaft  100  of the drive device, and the brake member  32  is moved from the braking position to the release position against a biasing force of the compression coil spring  42 . 
     Additionally, the rotary shaft  100  includes a rotary table  104  fixed to an upper end of a rotating shaft  102 , and the drive gear  106  which may be engaged with a reel gear  62  of the reel  28  is formed upward in the peripheral portion of the rotary table  104 . Therefore, the rotary shaft  100  is moved upward relative to the case  12  to engage the drive gear  106  with the reel gear  62 . A disc-shaped magnet (not shown) is provided in the radial inside of the drive gear  106  in the rotary table  104 , and the reel plate  66  of the reel  28  is attracted by a magnetic force of the magnet. 
     In the recording tape cartridge  10  described above, during the rotation of the reel  28  (drawing or winding of the magnetic tape T), the relative rotation is generated between the sliding contact projection  35  (brake member  32 ) which is not rotated with respect to the case  12  and the release pad  44  which is rotated along with the reel  28 , and the leading end (lower end) of the sliding contact projection  35  and the upper surface of the release pad  44  are slid by the relative rotation while contacting each other. 
     (Configuration of Reel) 
     As shown in  FIGS. 1 to 3 , the reel  28  includes a reel hub  45  constituting a axis center portion thereof. The reel hub  45  is formed into a substantially cylindrical shape with a bottom, and the reel hub  45  includes a cylindrical wall  46  and the bottom plate  48 . An outer circumferential surface of the cylindrical wall  46  constitutes a tape winding surface  46 A around which the magnetic tape T is wound. The bottom plate  48  is of a bottom portion which closes a lower portion of the cylindrical wall  46 . An upper flange  50  which is of the flange of the aspect of the invention is extended coaxially and integrally toward the radial outside from the upper end of the cylindrical wall  46  of the reel hub  45 , that is, from an opening end  46 B. In the exemplary embodiment, the opening end  46 B of the cylindrical wall  46  is flush with the upper surface of the upper flange  50 . 
     A circular center hole  48 A is formed in a axis center portion of the bottom plate  48  of the reel hub  45 . A window portion  48 B is also formed in the bottom plate  48  in order to project the engagement gear  52 , which provided in a center portion  58  of a lower flange member  60  (will be mentioned later), above its upper surface thereof. The plural window portions  48 B (six window portions whose number is matched with that of the engagement gears  52 ) are provided along a circumference which is coaxial with the reel hub  45 . A through-hole  48 C is formed in the bottom plate  48  in order to insert the leg portion  44 B of the release pad  44 . The three through-holes  48 C are provided at equal intervals along a circumference which is coaxial with and larger than the circumference on which the plural window portions  48 B are arranged. 
     In the reel hub  45  described above, the cylindrical wall  46  and the bottom plate  48  which are of the main parts are integrally formed by resin molding. In the exemplary embodiment, the upper flange  50  and the reel hub  45  are integrally formed by the resin molding. 
     As shown in  FIGS. 1 to 3 , the reel  28  also includes a lower flange  56  which is of the flange portion facing the upper flange  50 . The lower flange  56  is integrally extended toward the radial outside from the center portion  58  which is of the center portion bonded to the bottom plate  48  of the reel hub  45  (bonding structure is described later), and the lower flange  56  is fixedly retained by the reel hub  45  while the center portion  58  is interposed therebetween. The lower flange  56  and the center portion  58  constitute the lower flange member  60  which is of the flange member. 
     The reel gear  62  which can be engaged with the drive gear  106  of the rotary shaft  100  of the drive device is formed downward in the center portion  58  of the lower flange member  60 . In the reel gear  62 , plural teeth are arrayed so as to form an annular shape which is coaxial with the lower flange member  60 , that is, the reel  28  as a whole. 
     On the other hand, the engagement gear  52  which can be engaged with the braking gear  36  of the brake member  32  is formed upward from the upper surface side of the center portion  58 . That is, as described above, the engagement gear  52  is engaged with the braking gear  36  of the brake member  32  which is located at the braking position, and the engagement of the engagement gear  52  with the braking gear  36  of the brake member  32  is released to permit rotation of the reel  28  about the axis thereof when the brake member  32  is located at the release position. In the exemplary embodiment, the plural (six) engagement gears  52  are provided along the circumference which is coaxial with the reel hub  45 , and each engagement gear  52  can be pierced through the corresponding window portion  48 B of the reel hub  45 . 
     As shown in  FIG. 2 , a circular projection  54  which can be fitted in the center hole  48 A of the reel hub  45  is provided upward from the axis center portion of the center portion  58 . Through-holes  65  are formed near the periphery of the center portion  58 . The through-hole  65  and the through-hole  48 C of the reel hub  45  constitutes the unlock hole  64 , and the leg portion  44 B of the release pad  44  located in the reel hub  45  is projected toward the outside (lower side) of the reel hub  45  through the unlock hole  64 . The through-holes  65 , that is, the unlock holes  64  are arranged at equal intervals on a circumference in a region where the reel gear  62  is placed. Accordingly, the reel gear  62  is circumferentially divided by the unlock holes  64  (tooth of the reel gear  62  is not provided around the unlock hole  64 ). 
     In the lower flange member  60 , the lower flange  56 , the center portion  58 , the engagement gears  52 , the circular projection  54 , and the reel gear  62  which are of the main parts are integrally formed by the resin molding. 
     As shown in  FIGS. 1 and 5 , the reel plate  66  which is of the metal plate made of a magnetic material is fixedly provided in the center portion  58 . The reel plate  66  is formed into a substantial disc shape having a hole  66 A in the axis center portion, and the reel plate  66  is coaxially disposed on the radial inside of the reel gear  62 . The reel plate  66  is attracted in a noncontact manner by the magnetic force of the magnet provided in the rotary shaft  100  of the drive device. 
     The reel plate  66  is fixed to the center portion  58 , that is, the lower flange member  60  by the insert molding. Specifically, plural (in the exemplary embodiment, four) small holes  66 B are made in the reel plate  66  while pierced in a plate thickness direction of the reel plate  66 , and the small holes  66 B are circumferentially disposed at equal intervals along a virtual circle which is coaxial with the hole  66 A. In each small hole  66 B, the diameter is enlarged on the lower surface side of the reel plate  66  to form a so-called pillbox shape. The resin material is injected into a die, and each small hole  66 B is filled with the resin material. The resin material is cooled and solidified, whereby the reel plate  66  is strongly fixed to the lower flange member  60 . The reel plate  66  may be fixed to the lower flange member  60  by calking. 
     As described above, the lower flange member  60  is bonded to the bottom plate  48  of the reel hub  45  in the center portion  58 . Specifically, a welding projection (energy director, not shown) is provided from the lower surface of the bottom plate  48  before the welding, an ultrasonic vibration is imparted while the welding projection abuts on the upper surface of the center portion  58 , thereby performing the ultrasonic welding between the reel hub  45  and the lower flange member  60  in the portion where the welding projection is placed. 
     The welding portion is designated by the numeral W 1  of  FIG. 1 . As may be seen from  FIG. 1 , the reel hub  45  and the lower flange member  60  are bonded to each other within a region where the reel plate  66  is placed. More specifically, as shown in  FIG. 1 , the welding portions W 1  is formed along a circumference, and a diameter of the circumference is smaller than inner peripheries of the engagement gears  52  and reel gear  62 , and the diameter of the circumference is larger than an inner diameter of the hole  66 A, an outer diameter of the circular projection  54 , and a diameter of the virtual circle on which the small holes  66 B are arranged. In the exemplary embodiment, the welding portion W 1  is circumferentially divided into plural portions so as to form plural arc shapes in a planar view. 
     The reel  28  according to the exemplary embodiment of the invention includes a reinforcing ring  68  which is integrally provided on an inner circumferential side of the cylindrical wall  46  of the reel hub  45 . In the exemplary embodiment, the reinforcing ring  68  is provided only in an upper portion of the reel hub  45  in the axis line direction of the reel hub  45 , including the opening end  46 B of the cylindrical wall  46  of the reel hub  45 . The specific description will be made below. 
     The reinforcing ring  68  mainly includes a ring body  70 , an outer flange portion  72 , and an inner flange portion  74 . The ring body  70  is formed into a short cylindrical shape having a length of about a half of the cylindrical wall  46  of the reel hub  45 . The outer flange portion  72  is projected toward an outwardly radial direction from an upper end portion of the ring body  70 . The inner flange portion  74  is projected toward an inwardly radial direction from a lower portion of the ring body  70 . The reinforcing ring  68  is configured such that a predetermined clearance C (see  FIG. 1 ) is formed between the outer circumferential surface of the ring body  70  and the inner circumferential surface of the cylindrical wall  46 . 
     In the exemplary embodiment, sizes (tolerance) of the cylindrical wall  46  of the reel hub  45  and the ring body  70  of the reinforcing ring  68  are determined such that the clearance C becomes 0 mm&lt;C≦0.05 mm. That is, the ring body  70  is attached to the cylindrical wall  46  of the reel hub  45  by loose fit. The same clearance C is set between the outer circumferential surface of the outer flange portion  72  and an inner circumferential surface of a recess  46 C (described later). 
     The reinforcing ring  68  is fixed to the reel hub  45  by welding the lower surface of the outer flange portion  72  to the recess (step portion)  46 C. The recess  46 C is provided at the upper end of the cylindrical wall  46  of the reel hub  45  so as to be opened upward and radially inward. In the welded state, the upper surface of the outer flange portion  72  is substantially flush with the upper surface of the upper flange  50 . A numeral W 2  denotes a welded portion. A welded portion W 2  is formed by ultrasonic welding the cylindrical wall  46  of the reel hub  45  and the outer flange portion  72  of the reinforcing ring  68 . 
     That is, in the exemplary embodiment, the reinforcing ring  68  is made of a resin material which can be welded to the resin reel hub  45 . Specifically, the reinforcing ring  68  is made of the resin material in which a Young&#39;s modulus of about 9000 MPa is obtained by adding mica to polycarbonate (PC), while the reel hub  45  is made of polycarbonate (PC). The ring body  70  has a thickness of about 1 mm. 
     The inner flange portion  74  is formed into a ring shape whose inner diameter is slightly larger than the outer diameter of the brake member  32 . As shown in  FIG. 5 , when the braking gear  36  of the brake member  32  is engaged with the engagement gear  52 , that is, when the brake member  32  is located at a rotary lock position, the inner circumferential surface of the inner flange portion  74  faces the outer circumferential surface of the brake member  32  with a distance G which is a predetermined value or less. At this point, the distance G is set so as to range from 0.1 mm to 0.3 mm. Therefore, radial movement of the reel  28  is regulated with respect to the case  12  while the brake member  32  is interposed therebetween. 
     On the other hand, as shown in  FIG. 6 , when the brake member  32  is located at the rotary permission position, the inner flange portion  74  is not located on the outside in the radial direction of the brake member  32 . That is, the inner flange portion  74  is disposed such that overlap with brake member  32  in an axis line direction is eliminated by a stroke (movement) along the axis line direction between the rotary lock position and the rotary permission position of the brake member  32 . 
     The action of the exemplary embodiment will be described below. 
     In the recording tape cartridge  10  having the above-described configuration, when the recording tape cartridge  10  is not used, the brake member  32  is located at the rotary lock position by the biasing force of the compression coil spring  42 , and the brake member  32  engages the braking gear  36  with the engagement gear  52 . Therefore, the reel  28  is prevented from being rotated relative to the case  12 . At this point, the reel gear  62  of the reel  28  is exposed from the gear opening  20 , and the leg portion  44 B of the release pad  44  is projected through the unlock hole  64  to face the gear opening  20  while being able to be pressed from the outside. 
     On the other hand, in using the magnetic tape T, the recording tape cartridge  10  is loaded into a bucket (not shown) of the drive device along the direction of the arrow A. When the recording tape cartridge  10  is loaded into the up to a predetermined depth, the bucket is lowered, and the rotary shaft  100  of the drive device is relatively brought close to (move upward) the gear opening  20  of the case  12  to retain the reel  28 . Specifically, the rotary shaft  100  engages the drive gear  106  of the rotary shaft  100  with the reel gear  62  while attracting and retaining the reel plate  66  in a non-contact manner using the magnet. 
     The rotary shaft  100  upwardly presses the release pad  44  whose leg portion  44 B abutting on a tooth tip of the drive gear  106  in accordance with the engagement between the reel gear  62  and the drive gear  106 , that is, the movement of the rotary shaft  100  on the axial direction proximity side relative to the case  12 . Then the release pad  44  is moved upward in the axis line direction of the reel  28  against the biasing force of the compression coil spring  42  by the pressing force while guided by the unlock hole  64  in the leg portion  44 B. Therefore, in the sliding contact projection  35 , the brake member  32  abutting on the main body portion  44 A of the release pad  44  is also moved upward to release the engagement between the braking gear  36  of the brake member  32  and the engagement gear  52 . That is, the brake member  32  reaches the rotary permission position relative to the reel  28 . When the rotary shaft  100  is further relatively moved upward, the reel  28  is lifted along with the release pad  44  and the brake member  32  (while the relative position is not changed) against the biasing force of the compression coil spring  42 , and the lower flange  56  is separated from the annular rib  22  while the brake member  32  reaches the absolute rotary permission position (relative to the case  12 ). Therefore, the reel  28  is floated in the case  12 , and the reel  28  becomes able to be rotated while not brought into contact with the inner surface of the case  12 . 
     The positioning pins of the drive device invade into the positioning hole  24  and  26  of the case  12  by lowering the bucket, that is, the recording tape cartridge  10  in the drive device, and the positioning surfaces of the drive device abut on the positioning surfaces  24 A and  26 A of the case  12 . Therefore, the recording tape cartridge  10  is positioned in the horizontal and vertical directions with respect to the drive device. Then the drawing unit of the drive device draws the leader block  30  from the case  12  to guide the leader block  30  to the winding reel of the drive device while a drawing pin (not shown) of the drawing unit is engages with the engagement recess  30 A of the leader block  30 . The leader block  30  is fitted in the winding reel, and the arc surface  30 B partially constitutes a winding surface which winds the magnetic tape T. 
     At this state, when the leader block  30  is rotated integral with the winding reel, the magnetic tape T is drawn from the case  12  through the opening  18  while wound around the reel hub of the winding reel. At this point, the reel  28  of the recording tape cartridge  10  is rotated in synchronization with the winding reel by the torque of the rotary shaft  100 , which is transmitted by the drive gear  106  engaged with the reel gear  62 . The information is recorded in the magnetic tape T or the information recorded in the magnetic tape T is reproduced by a recording and reproducing head provided along a predetermined tape path of the drive device. At this point, the sliding contact projection  35  of the brake member  32  which may not be rotated relative to the case  12  is slid and contacted to the main body portion  44 A of the release pad  44  which is rotated relative to the case  12  along with the reel  28 . 
     On the other hand, the bucket in which the recording tape cartridge  10  is loaded is lifted when the magnetic tape T is rewound around the reel  28  to retain the leader block  30  in the neighborhood of the opening  18  of the case  12 . Then abutment is released between the drive gear  106  and the leg portion  44 B of the release pad  44  while the engagement is released between the reel gear  62  and the drive gear  106 , the release pad  44  is moved downward along with the brake member  32  by the biasing force of the compression coil spring  42 . Therefore, the brake member  32  is returned to a braking position at which the braking gear  36  of the brake member  32  is engaged with the engagement gear  52 . In accordance with the operation in which the brake member  32  and the release pad  44  are moved by the biasing force of the compression coil spring  42 , the reel  28  is also moved downward and returned to the initial state in which the reel gear  62  is exposed from the gear opening  20  while the lower flange  56  of the reel  28  abuts on the annular rib  22 . At this state, the recording tape cartridge  10  is discharged from the bucket. 
     In producing the reel  28  constituting the recording tape cartridge  10 , the reel hub  45  including the upper flange  50 , the lower flange member  60 , and the reinforcing ring  68  are separately formed by resin molding. The reel plate  66  is integrated with the lower flange member  60  by insert molding. 
     Then the reinforcing ring  68  is fixed to the reel hub  45 . Specifically, an ultrasonic vibration is generated from an ultrasonic horn while the outer flange portion  72  and the cylindrical wall  46  are clamped between a receiving table (not shown) abutting on the lower end surface of the cylindrical wall  46  of the reel hub  45  and the ultrasonic horn abutting on the upper surface of the outer flange portion  72  of the reinforcing ring  68 , thereby performing ultrasonic welding of the reel hub  45  and the reinforcing ring  68 . 
     Then, the lower flange member  60  is fixed to the reel hub  45 . Specifically, the engagement gear  52  of the lower flange member  60  is inserted in the window portion  48 B of the reel hub  45  while the circular projection  54  is fitted in the center hole  48 A of the reel hub  45 , and centering (positioning) is performed to the lower flange member  60  relative to the reel hub  45 . The ultrasonic vibration is generated from the ultrasonic horn, while the bottom plate  48 , the center portion  58  and the reel plate  66  are clamped between “the receiving table (not shown) abutting on the reel plate  66  at an area (between the reel gear  62  and each small hole  66 B) including a backside portion of the surface abutting on the welding projection of the center portion  58 ” and “the ultrasonic horn abutting on the backside of the surface having the welding projection of the bottom plate  48  (upper surface of the bottom plate  48 )”, thereby performing the ultrasonic welding of the reel hub  45  and the lower flange member  60 . Therefore, the reel hub  45  and the lower flange member  60  are fixed to each other to form the reel  28  in which the upper flange  50  and the lower flange  56  protect the magnetic tape T wound around the tape winding surface  46 A. 
     The rigidity on the side of the bottom plate  48  (lower end side) tend to become larger than the rigidity on the side of the opening end  46 B, in the reel having the reel hub  45  in which the bottom plate  48  is provided in one of end portions in the axis line direction of the cylindrical wall  46  while the opening end  46 B is formed in the other end portion of the cylindrical wall  46 . 
     In the reel  28  according to the exemplary embodiment of the invention, because the lower flange  56  is formed independently from the reel hub  45 , the increase in rigidity in the radial direction is prevented on the side of the bottom plate  48  in the reel hub  45 . On the other hand, in the reel  28 , because the upper flange  50  is integrally extended from the opening end  46 B of the cylindrical wall  46 , the rigidity in the radial direction is increased on the side of the opening end  46 B. Therefore, in the reel  28 , a difference in rigidity between the upper and lower ends of the cylindrical wall  46  becomes small in the reel hub  45 . In the reel  28 , because the reinforcing ring  68  is attached to the upper portion of the cylindrical wall  46  of the reel hub  45 , the difference in rigidity between the upper and lower ends of the cylindrical wall  46  is suppressed to a small level in the reel hub  45 . 
     In the reel of the exemplary embodiment, the radial rigidity is substantially equalized in the vertical direction of the cylindrical wall  46  of the reel hub  45 . Therefore, the deformation of the cylindrical wall  46  of the reel hub  45  is suppressed in the state where the magnetic tape T is wound around the tape winding surface  46 A, and the curvature of the magnetic tape T may be suppressed. Particularly, the deformation of the reel hub  45  of the resin reel  28  is effectively suppressed in a creep environment. 
     This point will be described in detail with reference to Table 1 showing comparison result and comparative examples. Table 1 shows numerical analysis results (decimals are rounded) of deformation amounts at upper and lower ends of the cylindrical wall  46  of the reel hub  45  and differences between the upper and lower deformation amounts in two types of creep environments. Each deformation amount is a deformation amount from the state that is before the magnetic tape T is wound. An environmental temperature of 40° C., relative humidity of 80%, and a retention period of one week are set as a first creep environment, and an environmental temperature of 60° C., relative humidity of 90%, and a retention period of one week are set as a second creep environment. The magnetic tape T is wound under the following predetermined conditions on the cylindrical wall  46  of the reel hub  45  of the exemplary embodiment: the tape winding surface  46 A has an outer diameter of 44 mm, the magnetic tape T has a width of 12.65 mm (½ inch), a thickness of 6.6 μm, and a length of 820 m, and the magnetic tape T is wound around the tape winding surface  46 A of the reel hub  45  while a tension of 70 g per section (above mentioned width×thickness). 
     As shown in  FIG. 7A , in a first comparative example, the lower flange  56  is integrally extended from the lower end of the cylindrical wall  46 , and the upper flange  50  which is of an independent member is welded to the opening end  46 B of the cylindrical wall  46 . As shown in  FIG. 7B , a reel of a second comparative example is similar to the reel  28  of the exemplary embodiment in that the upper flange  50  is integrally extended from the opening end  46 B while the lower flange member  60  is bonded to the bottom plate  48 , however, the reel of the second comparative example differs from the reel  28  in that reinforcing ring  68  is not provided. As shown in  FIG. 7C , a reel of a third comparative example is similar to the reel  28  in that reinforcing ring  68  is provided, however, the reel of the third comparative example differs from the reel  28  in that the lower flange  56  is integrally extended from the lower end of the cylindrical wall  46  while the upper flange  50  is formed independently of the reel hub  45 . In the third comparative example, although the upper flange  50  and the reinforcing ring  68  are integrally formed, it is considered that the integral formation of the upper flange  50  and the reinforcing ring  68  has no influence on the reinforcing effect. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 40° C. RH80 % 
                 60° C. RH90 % 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Upper 
                 Lower 
                 Differ- 
                 Upper 
                 Lower 
                 Differ- 
               
               
                 Reel 
                 end 
                 end 
                 ence 
                 end 
                 end 
                 ence 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 The 
                 33 
                 39 
                 −6 
                 41 
                 36 
                 5 
               
               
                 exemplary 
               
               
                 embodiment 
               
               
                 The first 
                 83 
                 12 
                 71 
                 130 
                 12 
                 118 
               
               
                 comparative 
               
               
                 example 
               
               
                 The second 
                 60 
                 41 
                 19 
                 95 
                 35 
                 60 
               
               
                 comparative 
               
               
                 example 
               
               
                 The third 
                 56 
                 13 
                 42 
                 85 
                 14 
                 71 
               
               
                 comparative 
               
               
                 example 
               
               
                   
               
            
           
         
       
     
     Table 1 shows that, in the first comparative example in which the rigidity at the lower end of the reel hub  45  is higher than that at the upper end, although the deformation amount at the lower end is suppressed to a small level under each condition, the difference in deformation amount between the upper and lower ends is increased because the deformation amount at the upper end becomes extremely larger than that at the lower end. In the second comparative example, compared with the first comparative example, the rigidity at the lower end is low and the rigidity at the upper end is high. When compared with the first comparative example, the deformation amount at the lower end is increased while the deformation amount at the upper end is decreased, and the difference in deformation amount between the upper and lower ends becomes smaller. In the third comparative example, compared with the first comparative example, the rigidity at the lower end is substantially same while the rigidity at the upper end is increased. When compared with the first comparative example, the deformation amount at the lower end is substantially same while the deformation amount at the upper end is decreased, and the difference in deformation amount between the upper and lower ends becomes smaller. However, the difference in deformation amount between the upper and lower ends becomes larger compared with the second comparative example in which the deformation amount at the lower end is increased. 
     On the other hand, in the reel  28  of the exemplary embodiment, the difference in rigidity between the upper and lower ends is substantially equalized as described above, the reel hub  45 , that is, the difference in deformation amount between the upper and lower ends of the tape winding surface  46 A is suppressed to an extremely small level. Particularly, under the severer creep condition (environmental temperature of 60° C., relative humidity of 90%, retention period of one week), it is confirmed in the exemplary embodiment that the difference in deformation amount between the upper and lower ends becomes 10% or less of each comparative example. 
     The effect may be achieved in theory by, for example, enhancing the rigidity of the reinforcing ring  68  of the third comparative example. However, in this case, various restrictions are generated. In the case where the rigidity is enhanced in the resin reinforcing ring  68 , moldability is lowered when the additive amount of mica is increased, and a countermeasure for avoiding interference with the brake member  32  is required when the thickness of the ring body  70  is increased. In the case where the reinforcing ring  68  is made of metal to enhance the rigidity, cost is increased because the metal material is selected such that the magnetic tape T is not influenced by the metal material, and the mass of the reel  28  is increased and the moldability or an assembling property is deteriorated. 
     On the other hand, in the reel  28  of the embodiment, not only that the reinforcing ring  68  is simply provided, but also that the increase in rigidity is suppressed at the lower end of the reel hub  45  by providing the lower flange  56  as the separate member, the rigidity is increased at the upper end of the reel hub  45  by integrally molding the upper flange  50 , and the reinforcing ring  68  is provided only in the upper portion of the cylindrical wall  46 . Therefore, without the various restraints mentioned above, it is realized that the rigidity is substantially equalized at both the ends in the axis line direction of the reel hub  45  using the small and light-weight reinforcing ring  68 . 
     Accordingly, in the reel  28 , the deformation of the tape winding surface  46 A of the reel hub  45  substantially becomes symmetrical relative to the center portion in the axis line direction (vertical direction) while the magnetic tape T is wound around the reel hub  45 , so that the curvature (tape curvature, see JJS X6175) of the magnetic tape T wound around the reel hub  45  can be suppressed. It is well known that the tape curvature is relatively small at room temperature but increased as the retention environmental temperature and humidity of the magnetic tape T is raised. In the reel  28 , the tape winding surface  46 A is substantially symmetrically deformed in relation to the vertical direction (vertical symmetry is maintained) under the environment in which the tape curvature is easily increased, so that tape curvature can effectively suppressed to a small level. 
     In the reel  28 , the reinforcing ring  68  is provided independently from the reel hub  45 , so that the upper flange  50  can be formed with good dimensional accuracy. In the reel  28 , the predetermined clearance C is set between the ring body  70  of the reinforcing ring  68  and the cylindrical wall  46  of the reel hub  45 , so that the tape winding surface  46 A can be formed with good dimensional accuracy. In the configuration in which the metal reinforcing ring is formed by the insert molding, there may be possibly of the reinforcing ring obstructs resin shrinkage in the opening end  46 B during the molding to affect the dimensional accuracy of the upper flange  50 . In the configuration in which the reinforcing ring is press-fitted in the reel hub  45 , there may be possibly of the deformation of the cylindrical wall  46  when press fitting affects the dimensional accuracy of the tape winding surface  46 A. However, in the reel  28 , the upper flange  50  and the tape winding surface  46 A can be formed with good dimensional accuracy. 
     The clearance C between the ring body  70  of the reinforcing ring  68  and the cylindrical wall  46  of the reel hub  45  is set in the range of 0 mm&lt;C≦0.05 mm, so that the sufficient reinforcing effect (improvement of the rigidity in the upper portion of the cylindrical wall  46  of the reel hub  45 ) can be obtained by the reinforcing ring  68 . Particularly the sufficient reinforcing effect can be obtained in the creep environment. 
     In the reel  28 , the reinforcing ring  68  is welded to the reel hub  45  at the lower surface of the outer flange portion  72  projected in the radial direction of the ring body  70 , so that the reinforcing ring  68  can securely be fixed to the reel hub  45  in the configuration in which the clearance C is set. On the other hand, because the clearance C of the dimension is set, the reinforcing ring  68  can easily be inserted into the reel hub  45  and accurately be positioned with respect to the reel hub  45  (centering can accurately be performed). 
     Because the reel  28  has the structure in which the lower flange  56  is fixed to the reel hub  45  (cylindrical wall  46 ) by bonding the center portion  58  to the bottom plate  48 , the lower flange  56  is hardly deformed in accordance with the deformation of the cylindrical wall  46 , which is caused by the winding pressure of the magnetic tape T. Particularly, in the reel  28 , because the center portion  58  is bonded to the bottom plate  48  in the region where the reel plate  66  in the lower flange member  60  is placed, in other words, because the center portion  58  is bonded to the reel hub  45  in the high-rigidity portion (portion reinforced by the reel plate  66 ) in the lower flange member  60 , the deformation such that swing is generated in the thickness direction is hardly generated in the lower flange  56 . Therefore, in the reel  28 , the runout in the thickness direction of an outer circumferential edge of the lower flange  56  can be decreased to ⅓ to ½ when compared with the configuration in which the inner edge of the lower flange  56  is bonded to the lower end surface of the cylindrical wall  46 . 
     Thus, in the reel  28 , the lower flange  56  has the high dimensional accuracy with respect to the reel hub  45 , and the deformation (runout) in the lower flange  56  caused by the deformation of the cylindrical wall  46  due to the winding pressure of the magnetic tape T is suppressed to a small level, so that a proper posture of the lower flange  56  can be ensured with respect to the reel hub  45  in each state. In the reel  28 , because the cylindrical wall  46  of the reel hub  45  is reinforced by the reinforcing ring  68 , the deformation caused by the winding pressure of the magnetic tape T is suppressed in the upper portion of the cylindrical wall  46 , and the deformation (runout) caused by the deformation of the cylindrical wall  46  is suppressed in the upper flange  50 . 
     In the recording tape cartridge  10  including the reel  28  as described above, the upper flange  50  and the lower flange  56  have the high dimensional accuracy with respect to the reel hub  45 , that is, the tape winding surface  46 A, and the runout (reduction of the distance between the surfaces facing each other) is suppressed in the upper flange  50  and the lower flange  56 . Therefore, the interference of the magnetic tape T with the upper flange  50  and the lower flange  56  is prevented to protect the magnetic tape T when the magnetic tape T is drawn from and inserted in the case  12 . 
     In the recording tape cartridge  10 , the inner flange portion  74  of the reinforcing ring  68  faces the brake member  32  located at the rotation lock position with the distance G that is the predetermined value or less. Therefore, the radial displacement of the brake member  32  relative to the reel  28 , that is, the radial position shift of the reel  28  relative to the case  12  can be suppressed. Accordingly, even in the vertical type drive device, the recording tape cartridge  10  of the present invention is not radially shifted in the period until the recording tape cartridge  10  is attracted by and engaged with the rotary shaft  100 , and the recording tape cartridge  10  is properly retained in the rotary shaft  100 . 
     In the exemplary embodiment, for the region where the reel gear  62  is formed, the unlock hole  64  is provided. However, the invention is not limited to the exemplary embodiment, and various modifications may be made. Accordingly, for example, in the recording tape cartridge  10  applying the reel  28 , other structures may be adopted to the structure for stopping the rotation of the reel  28  and the structure for releasing the stop of the rotation. 
     In the exemplary embodiment, the reinforcing ring  68  is made of the resin material to which mica is added. However, the invention is not limited to the exemplary embodiment. For example, the reinforcing ring  68  may be made of metal, a resin material which does not contain the reinforcing material, or a resin which includes glass fiber or carbon fiber as the reinforcing fiber. 
     In the exemplary embodiment, the lower flange  56  is bonded to the reel hub  45  with the center portion  58  interposed therebetween. However, the invention is not limited to the exemplary embodiment. For example, the lower flange  56  may be bonded to the reel hub  45  at the inner edge portion of the lower flange  56  which is formed into an annular shape.