JP2005108394A - Recording tape cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a recording tape cartridge in which vibration generated by the sliding contact of a member elastically supported by a case with a reel or a a member rotated together with the reel is suppressed. <P>SOLUTION: In the recording tape cartridge 10, a reel 28 received in a case 12 and having a magnetic tape T wound thereon is blocked for rotation by the engagement of a nonrotatable brake member 46 with the case 12 during nonuse, and rotated together with a release pad 64 by the disengagement of the brake member 46 when it is pushed up by the release pad 64. With this rotation, the brake member 46 comes in slide contact with a slide-contact projected part 68 disposed in the axial center of the release pad 64 while a pivot part 50 is pressed to the slide-contact projected part 68 by the the biasing force of a compression coil spring 60. When the reel 28 is rotated together with the release pad 64, μ×L≤0.4 is established in which L(mm) is the load length of the compression coil spring along the axial direction of the reel 28 and μ a coefficient of dynamic friction between a slide-contact surface 50A and the pivot part 68, and the self-excited vibration of the brake member 46 accompanying the slide-contact is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording tape cartridge that rotatably accommodates a reel on which a recording tape such as a magnetic tape is wound.

  A recording tape such as a magnetic tape is used as an external recording medium such as a computer. As this recording tape, a so-called one-reel recording tape cartridge is used which has a small storage space during storage and can record a large amount of information, and a single reel wound with a recording tape is rotatably accommodated in a case. Has been.

  Such a recording tape cartridge includes a lock mechanism so that the reel does not rotate in the case when not in use (see, for example, Patent Document 1). A recording tape cartridge provided with such a locking mechanism will be described with reference to FIG. In the recording tape cartridge 200 shown in FIG. 10, a single reel 204 is accommodated in the case 202. The case 202 includes a gear opening 206 provided at the center of the bottom plate 202A, and a rotation restricting rib 208 protruding downward from the top plate 202B.

  The reel 204 includes a reel hub 210 that is formed in a cylindrical shape with a bottom and on which a recording tape is wound around the outer periphery. A drive gear formed on the rotary shaft 212 of the drive device is formed on the bottom surface of the bottom 210A of the reel hub 210. A reel gear 214 that can mesh with 212A is formed in an annular shape. On the other hand, an engagement gear 216 is formed in an annular shape on the upper surface of the bottom portion 210A. In addition, a through hole 218 is provided in the axial center portion of the bottom portion 210A. Further, an annular reel plate 219 made of a magnetic material is fixed between the reel gear 214 and the through hole 218 on the lower surface of the bottom portion 210A.

  In the reel hub 210, a disc-shaped braking member (pressed member) 220 having an annular braking gear 220A that can mesh with the engagement gear 216 provided on the lower surface is inserted. The braking member 220 is configured such that a rotation restricting rib 208 of the case 202 is inserted into an engaging projection 222 erected from the upper surface of the braking member 220 so that the brake member 220 cannot rotate with respect to the case 202 and can move vertically. Further, the pivot portion 223 protruding from the lower surface axial center portion of the braking member 220 enters the through hole 218 of the reel hub 210 and faces the gear opening 206.

  A compression coil spring 224 is disposed between the top plate 202B of the case 202 and the braking member 220. Normally, the braking member 220 is urged downward by the urging force of the compression coil spring 224 to perform braking. The gear 220A meshes with the engagement gear 216. As a result, the recording tape cartridge 200 is in a rotation locked state in which the rotation of the reel 204 relative to the case 202 is prevented when not in use. Further, the reel 204 exposes the reel gear 214 from the gear opening 206 while the reel 204 is pressed against the bottom plate 202 </ b> A side of the case 202 by this biasing force.

  On the other hand, when the recording tape cartridge 200 is loaded into the drive device, the release portion 212B that protrudes from the axial center of the rotating shaft 212 is brought into contact with the pivot portion 223 of the braking member 220 as the drive gear 212A meshes with the reel gear 214. Abut and press. As a result, the braking member 220 is pushed upward against the urging force of the compression coil spring 224, and the meshing between the braking gear 220A and the engagement gear 216 is released.

  Then, when the drive gear 212A and the reel gear 214 are completely meshed and the reel plate 219 is attracted by the magnetic force of the magnet 212C of the rotary shaft 212, the rotary shaft 212 rotates around its axis, and the reel 204 becomes Rotates together. At this time, since the braking member 220 is not rotatable with respect to the case 202, the pivot portion 223 and the release portion 212B are in sliding contact with each other while being pressed against each other by the urging force of the compression coil spring 224. In order to reduce this sliding contact resistance, the release portion 212B on the drive device side is also made of a resin material with respect to the pivot portion 223 of the braking member 220 made of a resin material, and the tip of the pivot portion 223 is squeezed to make contact. The area is reduced.

  Further, a configuration in which a release member is interposed between the braking member 220 and the rotating shaft 212 is known (see, for example, Patent Document 2). The difference between this configuration and the recording tape cartridge 200 will be described with reference to FIGS.

  A recording tape cartridge 250 shown in FIG. 11 includes a release member 252 that is disposed between the bottom 210A of the reel hub 210 and the braking member 220 and is made of a resin material. As shown in FIG. 12, the release member 252 is formed in a substantially equilateral triangle shape in a plan view, and includes a leg portion 254 that protrudes downward from each top portion. Each leg 254 enters the insertion hole 256 provided in the bottom 210 </ b> A instead of the through hole 218 and faces the gear opening 206. Each insertion hole 256 is provided so as to penetrate the formation portion of the reel gear 214 in the bottom portion 210A.

  Further, a plurality of locking projections 258 are provided on the upper surface of the bottom portion 210 </ b> A instead of the engagement gear 216. The locking protrusions 258 are arranged at equal intervals along a predetermined circumference so as to avoid the tops of the release member 252, and gear teeth 258 </ b> A that can mesh with the braking gear 220 </ b> A are formed at the upper ends thereof. Yes. Further, a slidable contact projection 260 is projected from the upper surface axial center portion of the release member 252, and the slidable contact projection 260 is a substantially spherical pivot provided on the braking member 220 in place of the pivot portion 223. It is always in contact with the portion 262. The sliding contact projections 260 and 262 are both made of a resin material, and the pivot portion 262 is formed in a spherical shape so as to be brought into substantially point contact.

  When the recording tape cartridge 250 is not used, the braking gear 220A of the braking member 220 is engaged with the gear teeth 258A of the reel 204 by the urging force of the compression coil spring 224, thereby preventing the reel 204 from rotating with respect to the case 202. . In this state, the release member 252 abuts against the braking member 220 at the sliding contact portion 260 and the lower surface thereof is pressed against the bottom portion 210 </ b> A, and the end surface of each leg portion 254 located in the insertion hole 256 is the reel gear 214. It is almost flush with the tooth tip.

  On the other hand, when the recording tape cartridge 250 is loaded in the drive device, the leg 254 is pressed by the drive gear 212A and released as the reel gear 214 is engaged with the drive gear 212A of the rotary shaft 212 not provided with the release portion 212B. The member 252 is pushed upward against the urging force of the compression coil spring 224. Then, the release member 252 pushes up the braking member 220 while being separated from the bottom portion 210A, and the meshing between the braking gear 220A and the gear teeth 258A is released. In the state where the engagement between the drive gear 212A and the reel gear 214 is maintained, the release member 252 is configured to hold the brake member 220 at the release position by the leg portion 254 being in contact with the drive gear 212A. is there.

  The reel 204 rotates in the case 202 when the rotary shaft 212 rotates. At this time, the release member 252 that causes the leg portion 254 to enter the insertion hole 256 of the reel 204 rotates integrally with the reel 204, and the sliding contact projection 260 and the pivot portion 262 of the braking member 220 are connected to the compression coil spring. The two members slidably contact each other while being pressed by the urging force of 224.

  As described above, in the recording tape cartridges 200 and 250, as the reel 204 rotates, the pivot portion 223 of the braking member 220 and the release portion 212B of the rotary shaft 212, or the sliding contact protrusion of the pivot portion 262 and the release member 252 are obtained. 260 was in sliding contact with each other. For this reason, the brake member 220 supported by the compression coil spring 224 may self-vibrate due to the rotation of the reel 28 (the release portion 212B or the release member 252).

  The rotation speed of the reel 204 is expected to be increased due to a request for an increase in recording capacity and the like, and the sliding contact with the urging force of the compression coil spring 224 is supported as the rotation speed increases. There is a concern that abrasion or resin material may melt out at the contact part. When the state or shape of the sliding contact surface changes due to this wear or the like, the self-excited vibration of the braking member 220 is more likely to occur. Such self-excited vibration causes the urging force of the compression coil spring 224 to fluctuate, and the fluctuating urging force is transmitted to the case and the reel, causing the recording tape to become unstable.

  Moreover, the structure provided with the cancellation | release member 252 considers the structure which reduces the abrasion of the sliding contact site | part of the braking member 220 and the cancellation | release member 252 (for example, refer patent document 3). This structure will be described with reference to FIG. 13. A curved concave portion 264 is provided in the lower surface axial center portion of the braking member 220 in place of the pivot portion 262, and a sliding contact with the upper surface axial center portion of the release member 252 is provided. Instead of the portion 260, a pivot portion 266 protruding in a spherical shape is provided. An annular protrusion 268 is provided around the pivot portion 266. At least one of the braking member 220 and the release member 252 is made of a low-friction and low-wear material, and the curved concave portion 264 and the pivot portion 266 are substantially pointed as the reel 204 rotates. While being in sliding contact, the lower surface of the braking member 220 and the annular protrusion 268 are in sliding contact with each other in a surface contact state. As a result, the braking member 220 and the release member 252 are in sliding contact with low friction and low wear, and wear of the sliding contact portion is reduced.

  However, even with this configuration, it is difficult to completely prevent wear, and when wear occurs, it becomes easy to cause self-excited vibration of the braking member 220 as described above.

  Furthermore, the problem of the self-excited vibration as described above is not only in the lock mechanism that locks the rotation of the reel when not in use, but also in a portion that is elastically supported and is in sliding contact with the rotating portion as the reel rotates. May occur. For example, in a commercial two-reel recording tape cartridge (tape cassette) used in a broadcasting station or the like, a reel and a reel holder that supports the reel with respect to a case come into sliding contact with the rotation of the reel. (For example, refer to Patent Document 4).

  Specifically, as shown in FIGS. 14 and 15, the recording tape cartridge 270 houses two reels 274 rotatably in a case 272. A pivot portion 277 is formed on the upper surface of the hub 276 of each reel 274. On the other hand, on the top plate 272A of the case 272, the reel holder 280 is supported through the center cap 278 so as not to be rotatable and vertically movable, corresponding to the two reels 274, respectively. Each reel holder 280 is always in contact with the pivot portion 277 of the corresponding reel 274 while being urged downward by the compression coil spring 282. Accordingly, each reel 274 is supported so as to be swingable with respect to the case 272.

In the recording tape cartridge 270, when the reel 274 is rotated, the pivot portion 277 and the reel holder 280 are brought into sliding contact with each other while being pressed against each other by the urging force of the compression coil spring 282. Therefore, in the recording tape cartridge 270, the self-excited vibration of the reel holder 280 becomes a problem.
JP-A-63-251983 Japanese Patent No. 3187022 Japanese Patent Laid-Open No. 11-250618 JP 2003-45143 A

  As described above, in various conventional recording tape cartridges, a sliding member and a member such as a braking member of a lock mechanism and a reel holder that are elastically supported with respect to the case and rotate with the reel as the reel rotates. The problem that the self-excited vibration of the member in contact becomes a problem, and no means for solving this problem have been considered.

  In view of the above facts, the present invention has an object to obtain a recording tape cartridge that can suppress vibration generated when a member elastically supported by a case is in sliding contact with a reel or a member that rotates together with the reel. is there.

  In order to achieve the above object, a recording tape cartridge according to claim 1 is a reel around which a recording tape is wound, a case that rotatably accommodates the reel, and a non-rotatably supported case. A pressed member that can be brought into contact with and separated from the reel along the axial direction of the reel, and the case and the pressed member. When the reel is rotated, the pressed member is compressed in a compressed state. An elastic member that presses near the rotation center of the reel or a member that rotates together with the reel, and the length of the elastic member along the axial direction of the reel when rotating the reel is L (mm), When the coefficient of dynamic friction between the member to be pressed and the reel or a member that rotates together with the reel is μ, μ × L ≦ 0.4.

  The recording tape cartridge according to claim 1, wherein the pressed member is pressed near the rotation center of the reel or a member that rotates together with the reel (hereinafter referred to as a reel) by the urging force of the compressed elastic member. Rotate. For this reason, when the reel is rotating, the pressed member that does not rotate with respect to the case, the reel, and the like are in sliding contact with each other. The member that rotates together with the reel may be a component of the recording tape cartridge (for example, a release member that is operated when releasing the rotation lock of the reel), or a component (for example, a rotating shaft) on the drive device side. May be a release unit provided in the Further, the pressed member may be constantly pressed against the reel or the like by the urging force of the elastic member.

  Here, the relationship between the length of the elastic member along the axial direction of the reel when the reel is rotated (hereinafter referred to as the load length of the elastic member) L and the coefficient of dynamic friction μ between the pressed member and the reel, etc. The expression μ × L ≦ 0.4 shown is a stability discrimination expression. When the relationship of the expression is not satisfied, the amplitude of the self-excited vibration of the pressed member may increase (oscillate) over time. When the above relationship is satisfied, the self-excited vibration of the pressed member accompanying the sliding contact with the reel or the like during the rotation of the reel is attenuated. That is, in the present configuration that satisfies the above stability discriminant, vibration (periodic motion) of the pressed member is eliminated or the amplitude is remarkably reduced.

  As described above, in the recording tape cartridge according to the first aspect, it is possible to suppress the vibration generated when the member elastically supported by the case is in sliding contact with the reel or the member rotating together with the reel. For this reason, it is suppressed that the urging | biasing force of an elastic member fluctuates with the vibration of a to-be-pressed member, and a recording tape can be run stably. Further, since the self-excited vibration of the pressed member can be prevented or suppressed by setting the load length L of the elastic member and the dynamic friction coefficient μ, for example, a vibration damping member or the like for describing the vibration of the pressed member is provided. Compared with the configuration, the number of parts does not increase and the manufacturing cost can be reduced.

  In the present invention, the expression “near the center of rotation of a reel or the like” takes into account positional errors due to dimensional errors, assembly errors, wear, etc. of each member.

  As described above, the recording tape cartridge according to the present invention has an excellent effect that it can suppress vibration generated when the member elastically supported by the case is in sliding contact with the reel or a member rotating together with the reel. .

  A recording tape cartridge 10 according to an embodiment of the present invention will be described with reference to FIGS.

(Overall configuration of recording tape cartridge)
FIG. 1A shows a perspective view of the recording tape cartridge 10 as viewed obliquely from above, and FIG. 1B shows a perspective view of the recording tape cartridge 10 as viewed from obliquely below. FIG. 2 is a cross-sectional view of the recording tape cartridge 10. An arrow A shown in FIG. 1 indicates the loading direction of the recording tape cartridge 10 into the drive device. For convenience of explanation, the side indicated by the arrow A is the front side.

  As shown in these drawings, the recording tape cartridge 10 includes a case 12. The case 12 is configured by joining an upper case 14 and a lower case 16. Specifically, the upper case 14 is configured such that a substantially frame-shaped peripheral wall 14B is erected along the outer edge of the substantially rectangular top plate 14A in plan view, and the lower case 16 is substantially disposed on the top plate 14A. A peripheral wall 16B is erected along the outer edge of the bottom plate 16A having a corresponding shape. The case 12 has a substantially box-like shape in which the upper case 14 and the lower case 16 are joined by ultrasonic welding, screwing, or the like in a state where the opening end of the peripheral wall 14B and the opening end of the peripheral wall 16B are abutted. Is formed.

  In the case 12, the top plate 14A, the peripheral wall 14B, the bottom plate 16A, and the peripheral wall 16B are cut out at the corner corner on the leading side in the loading direction of the drive device, and an opening 18 that is inclined with respect to the outer loading direction is formed. Is formed. Further, a circular gear opening 20 penetrating through the bottom plate 16A is provided at a substantially central portion of the bottom plate 16A, and is used for exposing a reel gear 38 to be described later. An annular rib 22 protrudes inward of the case 12 at the edge of the gear opening 20 in the bottom plate 16A, and is used for positioning a reel 28 described later.

  Further, a pair of positioning holes 24 and 26 are opened near the front end of the outer surface of the bottom plate 16 </ b> A of the case 12. The pair of positioning holes 24 and 26 are provided in a bag shape in a protrusion (not shown) standing inward of the case 12 from the bottom plate 16A, and are spaced apart from each other on an imaginary line orthogonal to the loading direction. ing. The positioning hole 24 on the side close to the opening 18 has a substantially square shape as viewed from the bottom, which circumscribes the positioning pin of the drive device, and the positioning hole 26 is long along the imaginary line and has a width equal to the diameter of the positioning pin. It is a corresponding slot.

  Thus, when the recording tape cartridge 10 is loaded in the drive device and the positioning pins are inserted into the positioning holes 24 and 26, the recording tape cartridge 10 is accurately positioned in the horizontal direction (left and right and front and rear) in the drive device. It has come to be.

  Further, the portions around the positioning holes 24 and 26 in the bottom plate 16A are positioning surfaces 24A and 26A that are finished more smoothly than the other portions (design surfaces). The positioning surfaces 24A and 26A come into contact with the positioning surfaces of the drive device provided around the positioning pins when the positioning pins are inserted into the positioning holes 24 and 26, respectively. As a result, the recording tape cartridge 10 is also positioned in the vertical direction within the drive device.

  In the case 12 described above, as shown in FIG. 2, a reel 28 described in detail later is rotatably accommodated. Only one reel 28 is provided. A magnetic tape T as a recording tape is wound around the reel 28, and a leader block 30 as a drawing member is attached to the tip of the magnetic tape T.

  The leader block 30 is accommodated and held inside the opening 18 of the case 12 when the recording tape cartridge 10 is not used. In this state, the leader block 30 closes the opening 18 to prevent dust and the like from entering the case 12. The leader block 30 has an engagement recess 30A formed at the tip thereof, and when the magnetic tape T is pulled out in the drive device, the leader block 30 is pulled out from the case 12 by a drawing means that engages with the engagement recess 30A. And is guided to the take-up reel of the drive device. Further, the end face of the leader block 30 opposite to the engaging recess 30A is an arcuate surface 30B, and the leader block 30 is inserted into the take-up reel and constitutes a part of the take-up surface for winding the magnetic tape T. It is like that.

(Reel configuration)
As shown in FIGS. 2 and 3, the reel 28 is a substantially bottomed cylindrical reel hub having a cylindrical portion 32A around which the magnetic tape T is wound and a bottom portion 32B closing the lower portion of the cylindrical portion 32A. 32. Near the bottom 32B side end (lower end) of the reel hub 32, a lower flange 34 is coaxially and integrally extended outward in the radial direction. On the other hand, an upper flange 36 whose inner diameter is substantially the same as the inner diameter of the cylindrical portion 32A and whose outer diameter is the same as the outer diameter of the lower flange 34 is coaxially formed at the upper end portion of the reel hub 32 by ultrasonic welding or the like. Are joined together. Accordingly, the reel 28 is configured such that the magnetic tape T is wound around the outer peripheral surface of the cylindrical portion 32A of the reel hub 32 between the opposing surfaces of the lower flange 34 and the upper flange 36, and the cylindrical portion 32A is Is open.

  Further, as shown in FIG. 5, the bottom portion 32B of the reel hub 32 has a lower end slightly protruding from the lower surface of the lower flange 34, and an annular reel gear 38 is provided in the vicinity of the outer periphery of the lower end surface. It has been. The reel gear 38 can mesh with a drive gear 102 provided at the tip of the rotary shaft 100 of the drive device. Insertion holes 40 penetrating the bottom portion 32B (reel gear 38) are provided at three positions on the circumference of the reel gear 38 at equal intervals on the circumference. The diameter of each insertion hole 40 is larger than the gear pitch of the reel gear 38, and the teeth of the reel gear 38 are not provided around each insertion hole 40.

  Further, on the inner side of the reel gear 38 at the lower end surface of the bottom portion 32B of the reel hub 32, a reel plate 42 made of a magnetic material that can be attracted by the magnet 104 provided on the inner side of the drive gear 102 of the rotary shaft 100 is integrated by insert molding. Is provided. As shown in FIG. 2, the reel hub 32 has a bottom outer peripheral portion (in the vicinity of the boundary with the lower flange 34) of the bottom portion 32 </ b> B in contact with the upper end portion of the annular rib 22, and is lower than the lower flange 34 at the bottom portion 32 </ b> B. Also, the projecting lower end portion is inserted into the gear opening 20 of the case 12 (freely fitted). As a result, the reel gear 38 and the reel plate 42 are exposed to the outside of the case 12.

  On the other hand, as shown in FIG. 4, a pair (six in total) of locking projections 44 are coaxial with the reel hub 32 at three positions between the insertion holes 40 on the upper surface of the bottom portion 32 </ b> B of the reel hub 32. It is set up at regular intervals on the circumference. Gear teeth 44A are formed at the front end portions (upper end portions) of the respective locking projections 44 (see FIG. 2), and the gear teeth 44A can mesh with a braking gear 46A of a brake member 46 described later. .

(Configuration of lock mechanism)
Further, the recording tape cartridge 10 is provided with a lock mechanism 45 as a braking means for preventing rotation of the reel 28 when not in use. As shown in FIGS. 4 and 5, the lock mechanism 45 is provided in the present invention. The brake member 46 is provided as a “pressed member”.

  The brake member 46 includes a disc portion 48 formed in a substantially disc shape, and a brake gear 46A that can mesh with the gear teeth 44A of the reel 28 is annular in the vicinity of the outer periphery of the lower end surface of the disc portion 48. Is formed. In addition, a pivot portion 50 that abuts a later-described release pad 64 protrudes from the lower surface axial center portion of the disc portion 48. The pivot part 50 is formed in a substantially spherical shape, and is in point contact with the release pad 64.

  On the other hand, the brake member 46 includes a cross projection 52 that is erected from the upper surface of the disc portion 48 and has a substantially cross shape in plan view. A cross-shaped guide groove 52 </ b> A corresponding to this is formed inside the cross projection 52. That is, the cross projection 52 constitutes the groove wall of the guide groove 52A. A spring receiving recess 54 surrounded by an annular wall portion in plan view is formed outside the cross projection 52 on the upper surface of the disc portion 48.

  As shown in FIG. 5, the brake member 46 includes a through hole 56 that penetrates the disc portion 48 in the thickness direction. The through-hole 56 is formed in a rectangular shape corresponding to this portion so as to communicate with the radially outer portion excluding the intersecting portion which is the axial center portion of the guide groove 52A formed in a cross shape in plan view, and is divided into four. Has been. Each through hole 56 is located on the radially outer side than the pivot portion 50.

  The brake member 46 described above is integrally formed as a whole by resin molding. The brake member 46 is inserted in the cylindrical portion 32A of the reel hub 32 so as to be movable in the vertical direction (the axial direction of the reel 28) and substantially coaxially. That is, the brake member 46 moves in the vertical direction, so that the brake gear 46A meshes with the gear teeth 44A of the locking projection 44 provided on the reel hub 32 (rotation lock position that is the meshing position), and the meshing. It is possible to take a position for releasing (release position).

  And the cross rib 58 (refer FIG. 2 thru | or FIG. 5) protruding downward from the top plate 14A of the case 12 enters the guide groove 52A of the cross protrusion 52 of the brake member 46. The cross rib 58 has a non-rotating shape formed such that two thin plate pieces intersect each other so as to be orthogonal to each other, and engages with the cross protrusion 52 (groove wall of the guide groove 52A) to engage the brake member 46. It is the structure which prevents rotation with respect to the case 12.

  As a result, the brake member 46 prevents rotation of the reel 28 in a state where the brake gear 46A is positioned at a rotation lock position where the brake gear 46A meshes with the gear teeth 44A of the reel hub 32. Note that the cross rib 58 is maintained in the state of entering the guide groove 52A over the entire vertical movement stroke of the brake member 46, and the function of guiding the movement direction of the brake member 46 in the vertical direction. It is the structure which fulfills.

  In addition, projecting pieces 58 </ b> A are extended downward from the four locations excluding the intersection at the lower end of the cross rib 58. Each protruding piece 58A enters the through hole 56 of the brake member 46 when the brake member 46 is located at the release position (through and protrudes toward the braking gear 46A). As a result, the cross rib 58 having the protrusions 58 </ b> A greatly increases the amount of engagement (insertion depth) with the brake member 46 and suppresses the inclination of the brake member 46 with respect to the case 12. . In the present embodiment, the amount of engagement in the axial direction with the brake member 46 located at the rotation lock position of the cross rib 58 including each protruding piece 58 </ b> A is set sufficiently larger than the entire movement stroke of the brake member 46. (See FIGS. 2 and 3).

  A compression coil spring 60 as an “elastic member” is disposed in a compressed state between the spring receiving recess 54 of the brake member 46 and the top plate 14A. One end of the compression coil spring 60 enters the spring receiving recess 54 and comes into contact with the bottom surface of the spring receiving recess 54 (the upper surface of the disc portion 48), and the other end from the outside of the cross rib 58 in the top plate 14A. It abuts (engages) with the lower surface of an annular spring seat 62 projecting downward.

  The spring seat 62 is formed in a cylindrical shape having a diameter corresponding to the winding diameter of the compression coil spring 60, and the cross projection 52 of the brake member 46 located at the release position is inserted inside the spring seat 62. An annular wall portion 62A into which the other end portion of the compression coil spring 60 enters is projected downward from the outer peripheral portion of the spring seat 62, so that the compression coil spring 60 is not displaced in the radial direction. Yes. As described above, the compression coil spring 60 is disposed substantially coaxially with respect to the reel 28 and the brake member 46. The protrusion length of the spring seat 62 from the top plate 14A will be described later.

  In the lock mechanism 45, the brake member 46 is urged downward by the urging force of the compression coil spring 60, and the brake gear 46A is normally engaged with the gear teeth 44A as shown in FIG. In this configuration, inadvertent rotation is reliably prevented (the brake member 46 is positioned at the rotation lock position). In addition, the urging force also urges the reel 28 engaged with the brake member 46 in the locking projection 44 downward, and causes the outer peripheral portion of the bottom surface of the bottom portion 32B to abut the annular rib 22 in the case 12 as described above. It is designed not to rattle.

  Further, a release pad 64 as a release member is disposed between the bottom portion 32B and the brake member 46 in the reel hub 32 (cylindrical portion 32A) of the reel 28. The release pad 64 is formed in a flat plate shape having a substantially equilateral triangle in plan view, and three columnar leg portions 66 corresponding to the insertion holes 40 of the bottom portion 32B project from the lower surface in the vicinity of each top portion. Yes. On the other hand, a slidable contact protrusion 68 that comes into contact with the pivot portion 50 of the brake member 46 protrudes from the central portion on the upper surface of the release pad 64. The release pad 64 is integrally formed as a whole by resin molding.

  The release pad 64 is placed on the bottom portion 32B of the reel hub 32 (the lower surface is the bottom portion 32B) so as not to interfere with the locking projections 44 in a state where the leg portions 66 are inserted through the insertion holes 40 so as to be movable in the vertical direction. Is in contact with the upper surface of the substrate. In this state, each leg portion 66 protrudes from the lower end portion of the insertion hole 40 so that the tip end of the leg portion 66 and the tooth tip of the reel gear 38 are substantially the same. The release pad 64 is in contact with the pivot portion 50 of the brake member 46 in which the sliding contact projection 68 is positioned at the rotation lock position, so that the leg 66 is normally protruded by the urging force of the compression coil spring 60. It is the structure to maintain.

  On the other hand, when the leg portion 66 is pressed and moved upward against the urging force of the compression coil spring 60, the release pad 64 causes the brake member 46 that makes the pivot portion 50 abut on the sliding contact projection 68. The brake gear 46A and the gear teeth 44A of the locking projection 44 are released (pushing the brake member 46 to the release position).

  Specifically, as shown in FIG. 3, each leg 66 of the release pad 64 moves the rotary shaft 100 relative to the case 12 upward when the drive gear 102 is engaged with the reel gear 38 of the reel 28. Thus, it is pressed by the tooth tip of the drive gear 102. As a result, the reel 28 floats in the case 12 against the urging force of the compression coil spring 60 as the drive gear 102 is engaged with the reel gear 38 (the lower flange 34 is separated from the annular rib 22). ) And the rotation prevention state by the brake member 46 is released, and the case 12 can be rotated in a non-contact manner.

  As described above, the lock mechanism 45 is configured such that the sliding contact projection 68 and the pivot portion 50 are always brought into contact with each other by the urging force of the compression coil spring 60. In the state where the reel 28 is rotatable, the release pad 64 is configured such that each leg portion 66 is positioned in the insertion hole 40 of the reel hub 32 and rotates together with the reel 28 when the rotating shaft 100 rotates. For this reason, the brake member 46 and the release pad 64 that cannot rotate with respect to the case 12 rotate relative to each other when the reel 28 rotates, and the pivot portion 50 and the sliding contact projection 68 are pressed against each other by the urging force of the compression coil spring 60. It is the structure which is slidably contacted in a substantially point contact state.

  In the lock mechanism 45, as shown in FIG. 6, the length along the axial direction of the compression coil spring 60 when the brake member 46 is located at the release position (hereinafter referred to as “load length of the compression coil spring 60”, or It is set so that μ × L ≦ 0.4, where L is simply “load length” and μ is the dynamic friction coefficient between the pivot portion 50 and the sliding contact projection 68. Specifically, the dynamic friction coefficient μ between the pivot portion 50 and the sliding contact protrusion 68, both of which are made of a resin material, to reduce the sliding contact resistance is approximately 0.1, and this is substituted into the above equation. Then, the load length L of the compression coil spring 60, that is, the distance between the upper surface of the disc portion 48 of the brake member 46 located at the release position (position when the reel 28 rotates) and the lower surface of the spring seat 62 is 4 0.0 mm or less.

  In the present embodiment, the load length L of the compression coil spring 60 is set to 2.9 mm which is 4.0 mm or less. In order to realize this, the spring seat 62 with which one end of the compression coil spring 60 abuts is attached to the case 12. A configuration is employed in which the top plate 14A protrudes downward (on the brake member 46 side). That is, the protruding length of the spring seat 62 from the top plate 14A is determined so that the load length L of the compression coil spring 60 is 2.9 mm. The compression coil spring 60 has a wire diameter of approximately 0.8 mm and a winding number of 2.5 to 3. In FIG. 6, the cross rib 58 is partially cut away.

  Here, the relationship μ × L ≦ 0.4 between the load length L and the dynamic friction coefficient μ is a stability discriminant for determining whether or not the self-excited vibration of the brake member 46 occurs. This will be described later together with the operation of this embodiment.

  Next, the operation of the present embodiment will be described.

  In the recording tape cartridge 10 configured as described above, when not in use, the urging force of the compression coil spring 60 causes the brake member 46 to be positioned at the rotation lock position and meshes the braking gear 46A with the gear teeth 44A of the locking projection 44. . For this reason, the reel 28 is in a rotation locked state in which the rotation with respect to the case 12 is prevented. Further, the reel 28 is provided in the vicinity of the outer edge of the bottom portion 32 </ b> B (boundary portion with the lower flange 34) by the urging force of the compression coil spring 60 transmitted through the brake member 46 (and the release pad 64) that meshes with the locking protrusion 44. ) Is pressed against the annular rib 22.

  At this time, the reel gear 38 of the reel 28 is exposed from the gear opening 20, and each leg portion 66 of the release pad 64 passes through the insertion hole 40 and faces the gear opening 20 to the outside. The opening 18 is closed by the leader block 30.

  On the other hand, when using the magnetic tape T, the recording tape cartridge 10 is loaded into a bucket (not shown) of the drive device. When the recording tape cartridge 10 is loaded into the bucket to a predetermined depth, the bucket descends, and the rotary shaft 100 of the drive device relatively approaches (moves upward) toward the gear opening 20 of the case 12 to move the reel 28. Hold. Specifically, the rotating shaft 100 meshes the drive gear 102 with the reel gear 38 while attracting and holding the reel plate 42 in a non-contact manner by the magnet 104 disposed at the tip thereof.

  As the reel gear 38 and the drive gear 102 mesh with each other, the tooth tips of the drive gear 102 come into contact with the tips (lower end surfaces) of the leg portions 66 of the release pad 64, respectively. Against this, the release pad 64 is pushed upward. As a result, the brake member 46 in contact with the release pad 64 in the pivot portion 50 also moves upward, and the meshing between the brake gear 46A of the brake member 46 and the gear teeth 44A of the locking projection 44 is released.

  When the rotary shaft 100 moves further upward, the reel 28 is lifted upward together with the release pad 64 and the brake member 46 against the urging force of the compression coil spring 60 (without changing the relative position), and the lower flange 34 is moved. Separated from the annular rib 22. As described above, the reel 28 floats in the case 12 and can rotate in a non-contact state with the inner surface of the case 12.

  Further, when the bucket, that is, the recording tape cartridge 10 is lowered in the drive device, the positioning pins of the drive device enter the positioning holes 24 and 26 of the case 12, respectively, and the positioning surfaces 24A and 26A of the case 12 The positioning surface comes into contact. As a result, the case 12 is positioned in the horizontal direction and the vertical direction with respect to the drive device.

  Then, the draw-out means of the drive device pulls out the leader block 30 from the case 12 and guides it to the take-up reel of the drive device while engaging the draw pin (not shown) with the engagement recess 30A of the leader block 30. . Further, the leader block 30 is inserted into the take-up reel, and the arc surface 30B constitutes a part of the take-up surface on which the magnetic tape T is taken up. In this state, when the leader block 30 rotates integrally with the take-up reel, the magnetic tape T is drawn out from the case 12 through the opening 18 while being wound around the reel hub of the take-up reel.

  At this time, the reel 28 of the recording tape cartridge 10 is rotationally driven in synchronism with the take-up reel by the rotational force of the rotary shaft 100 transmitted by the drive gear 102 meshing with the reel gear 38. Then, information is recorded on the magnetic tape T or information recorded on the magnetic tape T is reproduced by a recording / reproducing head disposed along a predetermined tape path of the drive device.

  At this time, as the reel 28 rotates, the pivot portion 50 of the brake member 46 that cannot rotate with respect to the case 12 is compressed against the sliding contact protrusion 68 of the release pad 64 that rotates with the reel 28 with respect to the case 12. While being pressed by the urging force of the spring 60, it is in sliding contact with the sliding contact projection 68.

  On the other hand, when the magnetic tape T is rewound onto the reel 28 and the leader block 30 is held near the opening 18 of the case 12, the bucket loaded with the recording tape cartridge 10 is raised. Then, the engagement between the reel gear 38 and the drive gear 102 is released and the contact between the drive gear 102 and the leg portion 66 of the release pad 64 is released, and the release pad 64 is braked by the urging force of the compression coil spring 60. It moves downward with 46 (while maintaining the contact state).

  As a result, each leg portion 66 of the release pad 64 protrudes from the insertion hole 40 until the tip thereof substantially coincides with the tooth tip of the reel gear 38, and the braking gear 46A of the brake member 46 is gear teeth 44A of the locking projection 44. Mesh with. That is, the brake member 46 returns to the rotation lock position where the rotation of the reel 28 is prevented. The reel 28 also moves downward, and returns to the initial state in which the reel gear 38 is exposed from the gear opening 20 while being pressed against the annular rib 22 by the urging force of the compression coil spring 60.

  In this state, the recording tape cartridge 10 is ejected from the bucket, that is, the drive device.

  Here, in the recording tape cartridge 10, when the brake member 46 is positioned at the release position, that is, when the reel 28 rotates, the load length L of the compression coil spring 60 and the pivot portion 50 and the sliding contact projection 68 are Since the dynamic friction coefficient μ is set to satisfy μ × L ≦ 0.4, that is, the dynamic friction coefficient μ is set to 0.1, and the load length L is set to 2.9 mm which is 4.0 mm or less. The self-excited vibration of the brake member 46 due to the sliding contact between the pivot portion 50 and the sliding contact projection 68 when the reel 28 rotates is suppressed.

  That is, the relationship μ × L ≦ 0.4 between the load length L and the dynamic friction coefficient μ is the rotation of the reel 28 in the vibration system including the case 12, the brake member 46, and the compression coil spring 60 as described above. Is a stability discriminant for determining whether the self-excited vibration of the brake member 46 oscillates or attenuates, and when the relationship of this stability discriminant is not satisfied, it is in sliding contact with the pivot portion 50 as the reel 28 rotates. The brake member 46 enters an oscillation state in which the amplitude of the self-excited vibration increases with time due to the sliding contact with the protrusion 68, but the self-excited vibration of the brake member 46 is attenuated when the relationship of the stability discriminant is satisfied. Is known. In the present embodiment, since the dynamic friction coefficient μ is 0.1 as described above based on this knowledge, the load length L is set to 2.9 mm so as to satisfy the stability discriminant. The self-excited vibration of the brake member 46 is attenuated, and the vibration of the brake member 46 is eliminated or the amplitude is remarkably reduced.

  More specifically, as shown in the schematic diagram of FIG. 7A, the self-excited vibration of the brake member 46 is caused by the sliding contact S with the release pad 64 at the rotation center C (the brake member 46 and the release pad 64). It is likely to occur when it is displaced by a distance ΔX in the horizontal direction (the direction along the rotation surface of the release pad 64) with respect to the center of the relative rotation with respect to. 7A exaggerates the case where the state and shape of the sliding contact portion are changed due to wear (when displacement is likely to occur), the brake member 46, the release pad 64, the reel 28, the rotation The deviation of ΔX may occur due to a dimensional error or an assembly error of the shaft 100 or the like. FIG. 7B is a diagram (calculation result) showing the relationship of the stability determination value D to the deviation amount ΔX when the dynamic friction coefficient μ is fixed to 0.1. When the stability determination value D exceeds 0 (D> 0), this corresponds to the oscillation of the brake member 46 in an unstable state, and when it is 0 or less (D ≦ 0), the stability determination value D is stable. This corresponds to the damping of self-excited vibration.

  As is clear from this figure, in the configuration where the load length L is 2.9 mm, that is, the configuration of μ × L ≦ 0.4, the entire range of the deviation amount ΔX is stable, and the self-excited vibration of the brake member 46 is not generated. Attenuates. Further, in the configuration in which the load length L is 2.0 mm which is smaller than 2.9 mm, it is obvious that the load length L is stable over the entire range of the deviation amount ΔX, and the self-excited vibration of the brake member 46 is attenuated. On the other hand, in the configuration in which the load length L shown for comparison is 7.15 mm, that is, the configuration of μ × L = 0.715> 0.4, the brake member 46 is not stable over the entire range of the deviation amount ΔX. It can be seen that excitation vibration occurs (the brake member 46 oscillates).

  When the load length L corresponding to the upper limit of the stability discriminant is 4.0 mm (μ × L = 0.4), the load length L is stable over the entire range of the deviation amount ΔX, and the self-excited vibration of the brake member 46 is obtained. Can be seen to attenuate. The diagram shown in FIG. 7B shows that the damping rate (as a whole vibration system) in the vibration system constituted by the case 12, the brake member 46, and the compression coil spring 60 is about 0.01. The stability discrimination value D is 0 or less within the range satisfying the above stability discriminant even if the damping rate of the vibration system is estimated to be close to 0.005. It has been confirmed that it is stable (not shown).

  Further, in the actual measurement in any case where the damping rate of the vibration system is set to 0.01 or 0.005, the brake member 46 is subjected to the load length L = 4.0 mm and the load length L = 2.9 mm. It was confirmed that self-excited vibration was prevented. Therefore, sufficient self-excited vibration prevention (suppression) effect can be obtained even in an actual machine by satisfying the above stability discriminant. In the present embodiment in which the brake member 46 is made of a resin material, the damping rate of the vibration system is about 0.01.

  Further, the diagram shown in FIG. 7B is a calculation result when the load that the brake member 46 is pressed against the release pad 64 by the compression coil spring 60 having each load length L is approximately 4N. Even when the pressing load was increased and decreased with these load lengths L kept constant, a diagram almost identical to the diagram shown in FIG. 7B was obtained (not shown). Therefore, it has been confirmed that the above stability discriminant is valid without being influenced by the spring constant or natural length of the compression coil spring 60.

  As described above, since the recording tape cartridge 10 satisfies the stability determination formula, self-excited vibration of the brake member 46 is prevented or independent of the magnitude of the shift amount ΔX of the sliding contact S with respect to the rotation center C. It is suppressed. Therefore, if the sliding contact portion between the pivot portion 50 and the sliding contact projection 68 is worn and the sliding contact S is deviated from the rotation center C, that is, the self-excited vibration of the brake member 46 is likely to occur. Even in this case, in the recording tape cartridge 10 according to the present embodiment, the self-excited vibration of the brake member 46 is prevented or suppressed.

  As a result, in the recording tape cartridge 10, the urging force of the compression coil spring 60 is prevented from fluctuating with the rotation of the reel 28. In other words, the fluctuating urging force is applied to the case 12 and the reel 28 as a vibration force. The transmission is suppressed, and the magnetic tape T can be stably run (drawn or rewound).

  As described above, in the recording tape cartridge according to the present embodiment, it is possible to suppress the vibration generated when the brake member 46 elastically supported by the case 12 is in sliding contact with the release pad 64 that rotates together with the reel 28. Further, since the self-excited vibration of the brake member 46 can be prevented or suppressed by setting the load length L and the dynamic friction coefficient μ of the compression coil spring 60, the number of parts is smaller than that of a configuration in which, for example, a vibration damping member is provided. It is possible to reduce the manufacturing cost without increasing.

  As shown in FIG. 7B, when the deviation amount ΔX is larger than a predetermined value, stability against self-excited vibration increases, but there is a concern that forced vibration will occur. ) It is not preferable to set the deviation amount ΔX large.

(Modification of lock mechanism)
Next, a modification of the present embodiment will be described. Note that components / portions that are basically the same as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment, and description thereof is omitted.

  8 shows an exploded perspective view of a lock mechanism 80 according to a modification, and FIG. 9 shows a cross-sectional view of the lock mechanism 80. As shown in these drawings, the lock mechanism 80 is different from the lock mechanism 45 in that it includes a clutch member 82 as a release member instead of the release pad 64. This will be specifically described below.

  The reel 28 that is prevented from rotating with respect to the case 12 by the lock mechanism 80 includes a clutch boss portion 84 that holds the clutch member 82 so as to be operable from the outside, instead of the insertion hole 40. The clutch boss portion 84 is formed in a substantially cylindrical shape and protrudes upward from the axial center portion of the bottom portion 32B of the reel hub 32. The inside of the clutch boss portion 84 serves as a through hole 84A that also penetrates the bottom portion 32B in the plate thickness direction. ing. And the through-hole 42A is provided in the axial center part of the reel plate 42 which concerns on this modification corresponding to the through-hole 84A. Further, three rotation restricting grooves 84B and stopper grooves 84C are continuously provided on the radially outer side of the through hole 84A. Lower portions of the rotation restricting grooves 84B and the stopper grooves 84C are closed, and the stopper grooves 84C are configured to be shallower in the vertical direction than the rotation restricting grooves 84B. Further, from the upper surface of the bottom portion 32B, an engaging gear 86 that can mesh with the braking gear 46A is formed in a coaxial annular shape instead of the locking projection 44. In FIG. 8, the upper flange 36 is not shown.

  A brake member 88 serving as a “pressed member” constituting the locking mechanism 80 includes a substantially low-cylindrical main body 90 whose upper portion is closed instead of the disk portion 48. A cross projection 52 and a spring receiving recess 54 are provided on the upper surface of the bottom. The inner diameter of the main body 90 is sufficiently larger than the outer diameter of the clutch boss 84. Further, a pivot portion 50 projects from the bottom lower surface of the main body 90. The pivot part 50 is configured not to protrude from the lower end of the main body part 90. Further, an annular plate portion 92 extends radially outward from the axially intermediate portion of the main body portion 90, and a braking gear 46 </ b> A is provided on the lower surface of the annular plate portion 92.

  In the lock mechanism 80, the load length L of the compression coil spring 60 when the brake member 88 is located at the release position (the distance between the lower surface of the spring seat 62 and the upper surface of the main body 90 that is the bottom surface of the spring receiving recess 54). ) Is 2.9 mm (4.0 mm or less). The brake member 88 is integrally formed as a whole by resin molding.

  The clutch member 82 includes a main body portion 94 formed in a substantially cylindrical shape that can slide in the axial direction in the clutch boss portion 84 of the reel 28, and the lower end surface of the main body portion 94 is the rotation shaft 120. The operation surface 94 </ b> A is pressed by the release pressing portion 122. On the other hand, the upper end surface of the main body portion 94 is a sliding contact surface 94B with which the pivot portion 50 of the brake member 88 abuts. Further, three rotation restricting ribs 96 and seating ribs 98 extend radially outward from the upper part of the main body 94. The clutch member 82 is integrally formed as a whole by resin molding, and the dynamic friction coefficient μ between the sliding contact surface 94B and the pivot portion 50 of the brake member 88 is approximately 0.1.

  In the clutch member 82, each rotation restricting rib 96 enters a different rotation restricting groove 84B in a state where the main body portion 94 enters the through hole 84A (through hole 42A) of the clutch boss 84 and protrudes downward. Each seating rib 98 enters a different stopper groove 84C. When the brake member 88 is positioned at the rotation lock position where the braking gear 46A meshes with the engagement gear 86, each seating rib 98 abuts against the lower closed end of the stopper groove 84C. As a result, the clutch member 82 is prevented from falling off the reel 28, and is held so that it always rotates integrally with the reel 28, and can move upward and return from the rotation lock position.

  The rotation shaft 120 of the drive device includes a drive gear 102, a magnet 104, and a release pressing portion that is provided on the shaft center portion and presses the operation surface 94A of the clutch member 82 upward when the drive gear 102 is engaged with the reel gear 38. 122 is comprised.

  Therefore, in the recording tape cartridge provided with the lock mechanism 80 according to this modification, when not in use, the braking gear 46A of the brake member 88 is engaged with the engaging gear 86 of the reel 28, and the case 12 of the reel 28 is prevented from rotating. The When the magnetic tape T is used, the clutch member 82 is pressed by the release pressing portion 122 of the rotary shaft 120 on the operation surface 94A in accordance with the operation of engaging the drive gear 102 with the reel gear 38 by the lowering of the bucket. . As a result, the clutch member 82 is pushed upward against the biasing force of the compression coil spring 60, and the brake member 88 that is in contact with the clutch member 82 in the pivot portion 50 also moves upward (moves to the release position). ), The meshing between the braking gear 46A and the engaging gear 86 of the brake member 88 is released.

  When the rotation of the rotary shaft 120 is transmitted and the reel 28 rotates, the pivot portion 50 of the brake member 88 that cannot rotate with respect to the case 12 is brought into contact with the sliding contact surface 94B of the clutch member 82 that rotates integrally with the reel 28. While being pressed by the urging force of the compression coil spring 60, the sliding contact surface 94B is slidably contacted in a substantially rolling contact state.

  Here, in the configuration according to this modification, the load length L of the brake member 88 is 2.9 mm, and the dynamic friction coefficient μ between the pivot portion 50 and the sliding contact surface 94B is 0.1. The stability discriminant of L ≦ 0.4 is satisfied, and the self-excited vibration of the brake member 88 can be prevented or suppressed in the same manner as in the above embodiment. That is, the same effects as those of the above-described embodiment can also be obtained by the configuration according to this modification.

  In the above-described embodiment and modification, the configuration in which the dynamic friction coefficient μ is 0.1 and the load length L is 2.9 mm is illustrated, but the present invention is not limited to this, and the stability discriminant μ × L ≦ Needless to say, the dynamic friction coefficient μ and the load length L can be appropriately changed within a range satisfying 0.4. Therefore, the brake members 46 and 88, the release pad 64, and the clutch member 82 are not limited to a configuration made entirely of a resin material (a configuration in which the dynamic friction coefficient μ is approximately 0.1). A part (for example, a sliding contact part with the other party) can be configured by appropriately selecting a material other than a resin material such as a metal material. In this case, the damping rate of the vibration system constituted by the case 12, the brake member 46 (88), and the compression coil spring 60 is preferably 0.005 or more, and more preferably about 0.01.

  In the embodiment and the modification described above, the case 12 is provided with the spring seat 62 (raised portion), so that the load length L of the compression coil spring 60 during rotation of the reel 28 is 4.0 mm or less (stability determination). However, the present invention is not limited by the shape (configuration) of the brake member 46 or the case 12. Therefore, for example, the load length L may be 4.0 mm or less by providing a spring seat (raised portion) protruding upward from the disc portion 48 of the brake member 46, and the stability discriminant is satisfied by other configurations. May be.

  Moreover, in the said embodiment and modification, although it was set as the preferable structure provided with the compression coil spring 60 as an elastic member, when rotating the reel 28, the elastic member in this invention is between a case and a to-be-pressed member. Any member that is positioned in a compressed state and that presses the member to be pressed against the reel 28 or a member that rotates together with the reel 28 is sufficient. Therefore, for example, a leaf spring or the like formed in a substantially “<” shape can be employed as the elastic member. In addition, the elastic member in the present invention is not limited to a preferable configuration that is always in a compressed state (prevents rattling of the brake member 46 and the reel 28), and may be in a natural state when the reel 28 does not rotate.

  Furthermore, in the said embodiment and modification, although it was set as the structure which the brake members 46 and 88 slidably contact with the release pad 64 and the clutch member 82 which are the components of the recording tape cartridge 10, this invention is not limited to this, For example, the brake members 46 and 88 may be applied to a configuration in which the brake members 46 and 88 are in sliding contact with the components (parts) of the rotary shaft 100. Therefore, for example, the load length L, which is the distance between the tip of the pivot portion 223 and the top plate 202B (spring seat 62) in the braking member 220 shown in FIG. 10, and the dynamic friction coefficient μ between the pivot portion 223 and the release portion 212B. However, the above stability discriminant may be satisfied.

  Furthermore, in the above-described embodiment and modification, an example in which the present invention is applied to the lock mechanisms 45 and 80 has been shown. However, the present invention is elastically supported with respect to the case 12 and is accompanied with the rotation of the reel 28. Any configuration (shape) or usage of the pressed member can be applied as long as the pressed member is in sliding contact with the reel 28 or a member (part) rotating with the reel 28. it can. Therefore, for example, in a two-reel recording tape cartridge 270 as shown in FIGS. 14 and 15, the load length L of the compression coil spring 282 when the reel 274 is rotated, and the dynamic friction coefficient between the reel holder 280 and the pivot portion 277. μ may satisfy the above stability discriminant.

  In the above embodiment, the brake members 46 and 88 are configured to be in sliding contact with the release pad 64 and the clutch member 82 in a substantially point contact state. However, the present invention is not limited to this, and for example, the brake member 46 and the like. And the release pad 64 or the like may be in sliding contact with each other in a surface contact state such as a flat surface, a spherical surface, or a conical surface.

  Furthermore, in the above embodiment, the configuration in which the recording tape cartridge 10 has the leader block 30 is exemplified. However, in the present invention, the shape of the case 12, the drawing structure of the magnetic tape T (configuration of the leader member), the opening 18 Needless to say, the opening and closing structure is not limited. Therefore, for example, the recording tape cartridge 10 may have a configuration in which a small cylindrical leader pin is attached to the tip of the magnetic tape T as a leader member, and the shielding member that opens and closes the opening 18 (moves along a predetermined straight line or arc). It is good also as a structure which has a slide door etc. to do.

  Furthermore, in the above embodiment, the magnetic tape T is used as the recording tape. However, the present invention is not limited to this, and the recording tape is long and capable of recording information and reproducing the recorded information. Needless to say, the recording tape cartridge according to the present invention is applicable to any recording / reproducing system recording tape as long as it can be grasped as a tape-shaped information recording / reproducing medium.

1A and 1B are views showing an external appearance of a recording tape cartridge according to an embodiment of the present invention, wherein FIG. 1A is a perspective view seen from above, and FIG. 2B is a perspective view seen from below. FIG. 4 is a cross-sectional view of the recording tape cartridge according to the embodiment of the present invention when the reel is locked for rotation. FIG. 6 is a cross-sectional view of the recording tape cartridge according to the embodiment of the present invention when the reel is unlocked. FIG. 3 is an exploded perspective view of the lock mechanism constituting the recording tape cartridge according to the embodiment of the present invention as seen from above. FIG. 3 is an exploded perspective view showing the lock mechanism constituting the recording tape cartridge according to the embodiment of the present invention as seen from below. FIG. 2 is an enlarged cross-sectional view showing a lock mechanism that constitutes the recording tape cartridge according to the embodiment of the present invention. (A) is a schematic diagram for demonstrating the self-excited vibration generating mechanism of a brake member, (B) is a diagram which shows the vibration stability for every centerline height. It is a disassembled perspective view which shows the locking mechanism which concerns on the modification of embodiment of this invention. It is sectional drawing which shows the locking mechanism which concerns on the modification of embodiment of this invention. It is sectional drawing which shows the conventional 1st recording tape cartridge. It is sectional drawing which shows the conventional 2nd recording tape cartridge. FIG. 10 is an exploded perspective view of a lock mechanism constituting a conventional second recording tape cartridge. It is sectional drawing which shows the conventional 3rd recording tape cartridge. It is a disassembled perspective view which shows the conventional 4th recording tape cartridge. It is sectional drawing which shows the support state of the reel holder which comprises the conventional 4th recording tape cartridge.

Explanation of symbols

10 Recording Tape Cartridge 12 Case 28 Reel 46 Brake Member (Pressed Member)
60 Compression coil spring (elastic member)
64 Release pads (members that rotate with the reel)
82 Clutch member (member that rotates with the reel)
88 Brake member (pressed member)
T Magnetic tape (recording tape)

Claims (1)

A reel on which a recording tape is wound;
A case for rotatably accommodating the reel;
A pressed member supported by the case in a non-rotatable manner and capable of contacting and separating from the reel along the axial direction of the reel;
An elastic member that is provided between the case and the pressed member and presses the pressed member near the rotation center of the reel or a member that rotates together with the reel in a compressed state when rotating the reel;
With
When the length of the elastic member along the axial direction of the reel when rotating the reel is L (mm), and the dynamic friction coefficient between the pressed member and the reel or a member rotating with the reel is μ And μ × L ≦ 0.4.
A recording tape cartridge characterized by the above.

Images