JPH09180403A - Magnetic recording medium cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent, the interference of each reel, etc., while minimizing the amount of travel of a cartridge body due to the placement to a drive device. SOLUTION: When drive gears are engaged to corresponding gears 32 and 53 to be driven of reels 30 and 50, respectively, a reel spring 40 positions an upper-stage reel 30 to a specific position where it is displaced by a specific amount L1 in the thickness direction of a cartridge body 20 for the lower-stage reel 50, thus nearly simultaneously engaging the gears 32 and 53 to be driven of the reels 30 and 50 to a drive gear which is arranged in two stages with the amount of deviation corresponding to the specific amount L1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium cartridge for feeding or winding a magnetic recording medium such as a magnetic tape between a pair of reels. The present invention relates to a structure for surely preventing interference and the like of each reel while minimizing the above.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium cartridge, there is a magnetic tape cassette for feeding or winding a magnetic tape between a pair of rotatably provided inside a cartridge body. The respective reels are provided in the cartridge main body such that the centers of rotation are substantially parallel to each other with a predetermined gap.

[0003]

In the above-described conventional magnetic tape cassette, the reels are arranged in the cartridge body so as not to overlap in the thickness direction of the cartridge body. Therefore, it is necessary to secure a space corresponding to the outer diameter of each reel and a space corresponding to the winding diameter of the magnetic tape on each reel in the cartridge body, and there is a problem that the space efficiency in the cartridge body is extremely low. . Further, in order to increase the storage capacity, it is necessary to lengthen the magnetic tape, but when the magnetic tape is lengthened, the winding diameter of the magnetic tape on each reel becomes large. Therefore, it is necessary to significantly increase the outer dimensions of the cartridge body. That is, for example, when the winding diameter of the magnetic tape on each reel is doubled, the winding diameter of the magnetic tape inside the cartridge body is quadrupled for both reels, and the outer dimensions of the cartridge body are significantly increased.

Therefore, in order to increase the storage capacity while suppressing an increase in the size of the cartridge body, the pair of reels are arranged so that their centers of rotation are substantially aligned in the cartridge body, and the reels are spaced at predetermined intervals in the thickness direction of the cartridge body. It is conceivable that they are placed facing each other with an opening. in this case,
Considering the ease of mounting the cartridge main body to the required drive device, it is preferable to drive each reel from one side of the cartridge main body. Therefore, each reel is provided with a driven gear on one surface side of the cartridge main body, and the driving gear of the drive device is meshed with each driven gear. As a result, each reel rotates while being driven by the corresponding drive gear of the driven gear while the cartridge main body is mounted in the drive device in a predetermined posture, thereby feeding or winding the magnetic tape.

Here, in order to surely prevent interference between the reels and to make the cartridge body compact in the thickness direction, considering the dimensional accuracy of each reel, the drive gears of the drive device are respectively cartridges. It is desirable that the main body is arranged in two stages with a predetermined deviation in the thickness direction.
However, if the drive gears of the drive device are arranged in two stages, when the cartridge main body is mounted on the drive device, the meshing of the driven gears of the reels with the corresponding drive gears is sequentially performed along the thickness direction of the cartridge main body. It will be done in two stages. That is, first, the corresponding drive gear is engaged with the driven gear of the reel closer to the drive gear in the cartridge body, and then the corresponding driven gear of the reel located far from the drive gear in the cartridge body is driven. Gears mesh. In other words, when the cartridge body is mounted on the drive device, in order to engage the drive gears corresponding to the driven gears of the respective reels, it is necessary to make the movement amount of the cartridge body considerably large in the thickness direction. There was a problem that it was extremely difficult to achieve this.

According to the present invention, it is possible to surely prevent interference of each reel while minimizing the amount of movement of the cartridge main body when it is mounted on the drive unit, whereby the cartridge main body and the drive unit are compact. It is an object of the present invention to provide a magnetic recording medium cartridge which can be realized in a stable manner and which can stably rotate each reel.

[0007]

The above object of the present invention is to provide a predetermined interval in the thickness direction of the cartridge body such that the cartridge body is rotatable in the cartridge body and the centers of rotation are substantially coincident with each other. A pair of reels that are provided to face each other with a space between them and that feeds or winds the magnetic recording medium between each other, and that is provided on each reel and arranged in two stages with a predetermined deviation in the thickness direction of the cartridge body. The driven gears that rotate the reels as the drive gears rotate and the driven gears that rotate on the reels When the drive gears are meshed with each other, the reel on the other side in the thickness direction of the cartridge body is aligned with the reel in the thickness direction of the cartridge body. The reel recording means is provided with reel positioning means for positioning the reel on the side of the cartridge at a position displaced in the thickness direction of the cartridge body by a predetermined amount corresponding to the shift amount between the two-stage drive gears. Achieved by a media cartridge.

At the center of the reel on the other side in the thickness direction of the cartridge body, a boss portion is provided so as to project toward the drive gear side, and is provided at the center of the reel on the one side in the thickness direction of the cartridge body. It is preferable that the recessed portion is loosely inserted in the formed through hole, and a recess is formed on at least one of the outer peripheral surface of the boss portion and the inner peripheral surface of the through hole.

[0009]

In the magnetic recording medium cartridge according to the present invention, each of the pair of reels has a predetermined drive gear arranged in two stages with a predetermined amount of deviation in the thickness direction of the cartridge body, and the driven gear has the thickness of the cartridge body. By engaging with each other from one side in the direction, the drive gears rotate with the rotation of the drive gears, and the magnetic recording medium is fed or wound between them. When a predetermined drive gear is meshed with the driven gear of each reel, the reel positioning means sets the reel on the other side in the thickness direction of the cartridge body to the cartridge on the other side of the cartridge body in the thickness direction. The main body is positioned at a position displaced by a predetermined amount corresponding to the amount of deviation between the two-stage drive gears in the thickness direction. Therefore, the driven gears of the reels and the predetermined drive gears are engaged with each other almost at the same time. As a result, for example, the amount of movement of the cartridge body associated with mounting on the drive device is minimized, and
Interference between the reels is reliably prevented.

In the magnetic recording medium cartridge according to the present invention, each of the pair of reels has a predetermined drive gear arranged in two stages with a predetermined amount of deviation in the thickness direction of the cartridge body, and a driven gear of the cartridge body. By engaging with each other from one side in the thickness direction, the drive gears rotate with the rotation of the drive gears, and the magnetic recording medium is fed or wound between them. When a predetermined drive gear is meshed with the driven gear of each reel, the reel positioning means sets the reel on the other side in the thickness direction of the cartridge body to the cartridge on the other side of the cartridge body in the thickness direction. The main body is positioned at a position displaced by a predetermined amount corresponding to the amount of deviation between the two-stage drive gears in the thickness direction. Therefore, the driven gears of the reels and the predetermined drive gears are engaged with each other almost at the same time. As a result, for example, the amount of movement of the cartridge main body due to mounting on the drive device is minimized, and interference between the reels is reliably prevented. Further, a recess is formed on at least one of the outer peripheral surface of the boss portion of the reel on the other side in the thickness direction of the cartridge body or the inner peripheral surface of the through hole of the reel on the one side of the cartridge body in the thickness direction. Thus, the recesses more reliably prevent interference between the reels.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. 1 to 7 are views showing a magnetic recording medium cartridge according to a first embodiment of the present invention. FIG. 1 is a perspective view, FIG. 2 is an exploded perspective view of the magnetic tape cartridge of FIG. 1, and FIG. 1 is a perspective view showing a state in which the upper cover of the magnetic tape cartridge 1 is removed, and FIG. 4 is a view of the magnetic tape cartridge of FIG. 5 is a cross-sectional view showing the main part of the magnetic tape cartridge of FIG.
(A) shows a state in which each reel is locked, and (b) shows a state in which each reel is driven by a drive device. 6 is a perspective view showing the magnetic tape cartridge of FIG. 1 in an upside down state, and FIG. 7 is an exploded perspective view of the magnetic tape cartridge of FIG.

In FIGS. 1 and 2, the magnetic tape cartridge 10 is mounted in a predetermined drive device (not shown) in a predetermined posture, and a pair of reels 30 and 50 provided in the cartridge body 20 are attached to the cartridge body 20. It is driven by a predetermined drive gear (not shown) of the drive device from one surface side (lower surface side in FIG. 2). This allows a magnetic tape (not shown) between the reels 30 and 50.
Is sent or wound. The drive gears of the drive device are arranged in two stages in the thickness direction of the cartridge body 20 with a predetermined deviation amount.

Referring to FIGS. 1-4, 6 and 7,
The cartridge body 20 includes an upper cover 21 and an upper cover 2
It is composed of a lower cover 22 that can be fitted to the unit 1. A through hole 23 is provided substantially in the center of the lower cover 22, and guide rollers 24 are provided at the four corners of the inner surface of the lower cover 22, respectively.
Is provided. Each guide roller 24 is connected to each reel 30,
Guide the magnetic tape that is fed or wound between 50.

The upper cover 21 and the lower cover 22 are each provided with a notch 25 at a corresponding predetermined position (in the center of the front side in FIG. 2). The covers 21 and 22 are fitted so as to overlap the cutouts 25, and the cutouts 25 form the required openings 26. Each cover 2
A slide shutter 27 that is slidable in the left and right directions in FIG. The slide shutter 27 has the opening 2 when the cartridge body 20 is not mounted on the drive device.
When 6 is closed and the cartridge body 20 is mounted in the drive device in a predetermined posture, the cartridge body 20 is slid along the covers 21 and 22 in the diagonally right direction in FIG. 2 to open the opening 26. A magnetic head or the like (not shown) is inserted into the opened opening portion 26, and various information is magnetically recorded on the magnetic tape between the reels 30 and 50 by the magnetic head or the like, or various information magnetically recorded on the magnetic tape. Is read.

The pair of reels 30 and 50 are rotatably provided in the cartridge body 20 so that the centers of rotation thereof are substantially coincident with each other, and are overlapped in the thickness direction of the cartridge body 20 (vertical direction in FIG. 2). And are opposed to each other at a predetermined interval. Each reel 30, 50 is driven by the corresponding drive gear,
By rotating in a predetermined direction, the magnetic tape is fed or wound between them.

A cylindrical boss portion 31 is provided substantially at the center of the upper surface of the upper reel 30 in FIG. 2 (hereinafter referred to as the upper reel 30) in FIG. A metal plate 35 is provided at the tip (upper end in FIG. 7) of the boss portion 31, and a driven gear 32 is provided on the outer periphery of the metal plate 35. Boss part 3
1, the metal plate 35 and the driven gear 32 are loosely inserted into the through holes 51 of the lower reel 50 (hereinafter referred to as the lower reel 50) in FIG. 2, and the metal plate 52 and the driven gear of the lower reel 50 are driven. It is loosely inserted together with the gear 53 into the through hole 23 of the lower cover 22 and exposed on the lower surface of the lower cover 22.

As shown in FIG. 5A, the upper reel 30 has a reel spring 40, which is a coil spring, when the driven gear 32 is not meshed with the drive gear.
By a spring force (described later), the cartridge main body 20 is held at a predetermined lower position (hereinafter referred to as an upper reel lock position) displaced by a predetermined amount L1 from the lower cover 22 lower surface position. The displacement amount L1 is set to a value slightly smaller than the displacement amount in correspondence with the displacement amount between the two-stage drive gears of the drive device. In the present embodiment, the driven gear 32 or 53 of FIG.
Almost equal to the vertical dimension. In the upper reel lock position, the upper reel 30 is engaged with the lock gear 34 provided on the lower surface in FIG. 5 by the lock gear 54 of the lower reel 50 and is fitted into the lock groove 55 of the lower reel 50 by the reel lock gear 28. , And is held in a non-rotatable state together with the lower reel 50. The reel lock gear 28
Is provided on the lower cover 22 of the cartridge body 20.

As shown in FIG. 5B, the upper reel 30 is pressed by the drive gear when the driven gear 32 meshes with the driven gear 32 and is displaced upward by a predetermined amount in FIG. A predetermined amount L2 from the lower surface position of the lower cover 22 of 20
It is held at the displaced predetermined elevated position (hereinafter referred to as the upper reel drive position). At the upper reel drive position, the upper reel 30 is disengaged from the lock gear 34 and the lock gear 54 of the lower reel 50, and is rotated in a predetermined direction as the driven gear 32 is driven by the drive gear. At this time, the upper reel 30 attracts the metal plate 35 downward in FIG. 5 by the magnetic force of a magnet (not shown) on the driving device side, and at the same time, drives the driven gear 32 by the downward biasing force of the reel spring 40. The drive gear is securely meshed with a predetermined positional relationship. The metal plate 35 of the upper reel 30 may be omitted, and in this case, the corresponding magnet on the drive device side is also omitted.

As shown in FIGS. 5A and 5B, the reel spring 40 is provided between the upper reel 30 and the upper cover 21 of the cartridge body 20, and the reel plate 41 and the reel holder 42 are connected to each other. A spring force is applied to the upper reel 30 via the above. That is, the reel spring 40 has its upper end in FIG. 5 fitted to the inner circumference of the cylindrical portion 29 projecting from the inner surface of the upper cover 21 of the cartridge body 20, and its lower end in FIG. 5 to the inner surface of the reel holder 42 (see FIG. 5 is fitted to the outer circumference of the protruding portion 43 that is provided on the upper surface). The left and right ends of the reel plate 41 in FIG. 5 are fitted into the fitting grooves 36 of the upper reel 30, and the substantially central portion is engaged with the lower surface of the reel holder 42 in FIG.

With reference to FIGS. 2, 6 and 7, a through hole 51 is provided substantially in the center of the lower reel 50, and the boss portion 31 of the upper reel 30 is loosely inserted in the through hole 51. . A recess 51a is formed on the inner peripheral surface of the through hole 51. The recess 51a creates a required space between the lower reel 50 and the boss portion 31 of the upper reel 30, and reliably prevents interference between the reels 30 and 50, particularly when they are mounted on the drive device. . A metal plate 52 is provided around the through hole 51 on the upper surface of the lower reel 50 in FIG. 7, and a driven gear 53 is provided on the inner periphery of the metal plate 52. The metal plate 52 and the driven gear 53 are loosely inserted into the through holes 23 of the lower cover 22 of the cartridge body 20, and are exposed on the lower surface of the lower cover 22 together with the driven gear 32.

As shown in FIG. 5A, the lower reel 50 has the lock gear 54 and the lock gear 3 of the upper reel 30 in a state in which the drive gear is not meshed with the driven gear 53.
4 is engaged, and is urged downward in FIG. 5 by the spring force of the reel spring 40 via the lock gears 34 and 54. As a result, the lower reel 50 is held at a position where the reel lock gear 28 is fitted into the lock groove 55 provided on the lower surface in FIG. 5 (hereinafter, referred to as lower reel lock position).

When the driven gear 53 is engaged with the driven gear, the lower reel 50 is pressed by the driven gear and displaced upward by a predetermined amount L3 in FIG. 5, and the position shown in FIG. The lower reel drive position). At the lower reel drive position, the lower reel 50 is disengaged from the lock gear 54 and the lock gear 34 of the upper reel 30, and is rotated in a predetermined direction as the driven gear 53 is driven by the drive gear. At this time, the lower reel 50 is driven by the magnetic force of a magnet (not shown) on the driving device side.
The metal plate 52 is sucked downward in FIG. 5, and the driven gear 53 is reliably meshed with the driving gear in a predetermined positional relationship.

The operation of the present embodiment will be described. The upper and lower reels 30 and 50 are respectively the cartridge body 20.
2 is mounted on the drive device in a predetermined posture, the driven gears 32 and 53 are driven and rotated by the drive gear meshed from the lower surface side of the cartridge body 20 in FIG. Is sent out or wound up through the guide roller 24. In the magnetic tape between the reels 30 and 50, various information is magnetically recorded by a magnetic head or the like in the vicinity of the opening 26 of the cartridge body 20, or various magnetically recorded information is read.

Driven gears 32, 5 of each reel 30, 50
3, when the corresponding drive gears are engaged with each other, the reel spring 40 causes the upper reel 30 to move to the lower reel 5
A predetermined amount L in the thickness direction of the cartridge body 20 with respect to 0
The lower reel 50 is positioned at the upper reel lock position which is displaced one position, and the lower reel 50 is positioned at the lower reel lock position via the upper reel 30 and the lock gears 34 and 54. Therefore, the driven gears 32 and 53 of the reels 30 and 50 and the drive gears arranged in two stages with a shift amount corresponding to the predetermined amount L1 are engaged substantially at the same time. As a result, the amount of movement of the cartridge body 20 (or the amount of movement of the driving device) associated with mounting on the driving device is minimized, and interference between the reels 30 and 50 is reliably prevented.

As described above, according to the above-described embodiment, when the corresponding drive gears are engaged with the driven gears 32 and 53 of the reels 30 and 50, respectively, the reel spring 40 is used.
Positions the upper reel 30 at the upper reel lock position displaced by a predetermined amount L1 in the thickness direction of the cartridge body 20 with respect to the lower reel 50.
The zero driven gears 32 and 53 and the drive gears arranged in two stages with a shift amount corresponding to the predetermined amount L1 are engaged substantially at the same time. Therefore, the amount of movement of the cartridge main body 20 (or the amount of movement of the drive device) associated with mounting on the drive device can be minimized, and
It is possible to reliably prevent interference between the reels 30 and 50. Moreover, since the recess 51a is formed on the inner peripheral surface of the through hole 51 of the lower reel 50, the reels 30, 50 are
It is possible to more reliably prevent the interference and the like.
As a result, the cartridge main body 20 and the drive device can be made compact especially in the thickness direction of the cartridge main body 20, and the reels 30 and 50 can be stably rotated, so that the magnetic tape can be fed or wound. It can be performed stably. In addition, the mountability of the cartridge body 20 to the drive device can be stabilized.

Further, the reels 30 and 50 are rotatably provided in the cartridge body 20 so that the centers of rotation thereof are substantially coincident with each other, and are predetermined in the thickness direction of the cartridge body 20 (vertical direction in FIG. 2). The two are facing each other. Therefore, although the thickness of the cartridge body 20 is slightly increased, the outer dimensions of the cartridge body 20 can be significantly reduced. As a result, even if the length of the magnetic tape is lengthened and the storage capacity is significantly increased, it is possible to minimize the increase in the outer dimensions of the cartridge body 20.

Further, the respective reels 30, 50 are engaged with each other by the spring force of the reel spring 40 acting on the upper reel 30, and the respective lock gears 34, 54 are meshed with each other, and the reel lock gears are fitted in the lock grooves 55 of the lower reel 50. 28 is fitted and held at each lock position shown in FIG. Therefore, it is not necessary to separately provide a brake mechanism or the like for preventing the reels 30 and 50 from being rotated carelessly, the number of parts can be reduced, the structure can be simplified, and the cost can be reduced.

In the above embodiment, the recess 51a is formed on the inner peripheral surface of the through hole 51 of the lower reel 50 to create a required space between the lower reel 50 and the boss portion 31 of the upper reel 30. The interference between the reels 30 and 50 is prevented more reliably. The recess 51a is formed on the lower reel 50 in consideration of the ease of molding omission during reel molding. However, by forming the recess 51a on the outer peripheral surface of the boss portion 31 of the upper reel 30, A required space may be created between the boss portion 31 of the reel 30 and the lower reel 50. In addition, the concave portion 51a
Is not formed on either the outer peripheral surface of the boss portion 31 of the upper reel 30 or the inner peripheral surface of the through hole 51 of the lower reel 50, and as shown in FIG. The inner peripheral surfaces may be configured as opposed vertical surfaces (second embodiment).

[0029]

As described above, according to the present invention, when a predetermined drive gear is meshed with the driven gear of each reel, the reel positioning means causes the reel on the other side in the thickness direction of the cartridge body to move, With respect to the reel on one side in the thickness direction of the cartridge body, the cartridge is positioned at a position displaced by a predetermined amount in the thickness direction of the cartridge body, which corresponds to the amount of deviation between the two drive gears. The meshing with the predetermined drive gear is performed almost at the same time. Therefore, for example, the amount of movement of the cartridge main body accompanying the mounting on the drive device can be minimized, and interference between the reels can be reliably prevented. As a result, the cartridge main body and the driving device can be made compact, each reel can be stably rotated, and the magnetic recording medium can be stably fed or wound. Further, the reels are provided in the cartridge body so as to be rotatable and to face each other at a predetermined interval in the thickness direction of the cartridge body so that the centers of rotation are substantially coincident with each other. Therefore, it is possible to significantly increase the storage capacity while suppressing the size increase of the cartridge body as much as possible. Further, according to the present invention, when a predetermined drive gear is meshed with the driven gear of each reel, the reel positioning means sets the reel on the other side in the thickness direction of the cartridge body to the one side in the thickness direction of the cartridge body. The reels are positioned at positions displaced by a predetermined amount in the thickness direction of the cartridge main body in the thickness direction of the cartridge body, so that the driven gears of the reels and the predetermined drive gears are not meshed with each other. , Will be done almost at the same time. Therefore, for example, it is possible to minimize the movement amount of the cartridge main body due to mounting on the drive device, and
Interference between the reels can be reliably prevented. In addition, a recess is formed on at least one of the outer peripheral surface of the boss portion of the reel on the other side in the thickness direction of the cartridge body and the inner peripheral surface of the through hole of the reel on the one side in the thickness direction of the cartridge body. Therefore, it is possible to prevent interference between the reels more reliably. As a result, the cartridge main body and the driving device can be made compact, each reel can be stably rotated, and the magnetic recording medium can be stably fed or wound. In addition, each reel
The cartridge body is provided rotatably in the cartridge body so that the centers of rotation thereof are substantially coincident with each other in the thickness direction of the cartridge body with a predetermined gap therebetween.
Therefore, it is possible to significantly increase the storage capacity while suppressing the size increase of the cartridge body as much as possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a magnetic tape cartridge according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the magnetic tape cartridge of FIG.

3 is a perspective view showing a state in which an upper cover of the magnetic tape cartridge of FIG. 1 is removed.

4 is a view on arrow A of the magnetic tape cartridge of FIG.

5 is a cross-sectional view showing a main part of the magnetic tape cartridge of FIG.

6 is a perspective view showing an upside down state of the magnetic tape cartridge of FIG. 1. FIG.

FIG. 7 is an exploded perspective view of the magnetic tape cartridge of FIG.

FIG. 8 is a sectional view showing a main part of a magnetic tape cartridge according to a second embodiment of the present invention.

[Explanation of symbols]

10 magnetic recording medium cartridge (magnetic tape cartridge) 20 cartridge body 30 reel on the other side in the thickness direction of the cartridge body (upper reel) 31 boss portion of upper reel 32 driven gear (driven gear of upper reel) 34 lock gear 40 reel Positioning means (reel spring) 41 Reel positioning means (reel plate) 42 Reel positioning means (reel holder) 50 Reel on one side in the thickness direction of the cartridge body (lower reel) 51 Lower reel through hole 51a Recessed portion 53 Driven gear ( Driven gear of lower reel) 54 Lock gear L1 Displacement amount of upper reel when drive gear is not meshed (= deviation amount between drive gears) L2 Displacement amount of upper reel when drive gear is meshed L3 Drive gear is Mesh Displacement of the lower reel in state

Claims (2)

[Claims] 1. A cartridge main body and a cartridge main body, which are rotatably provided in the cartridge main body and face each other at predetermined intervals in the thickness direction of the cartridge main body so that their centers of rotation are substantially coincident with each other. In the cartridge main body, a pair of reels for feeding or winding the magnetic recording medium, and a predetermined drive gear provided on each reel and arranged in two stages with a predetermined shift amount in the thickness direction of the cartridge main body. When the gears are engaged from one side in the thickness direction, the driven gears that rotate the reels as the drive gears rotate, and when the driven gears of the reels engage the predetermined drive gears, respectively, the cartridge main body The reel on the other side in the thickness direction with respect to the reel on the other side in the thickness direction of the cartridge body. In the thickness direction of the main body,
A magnetic recording medium cartridge, comprising: a reel positioning means for positioning at a position displaced by a predetermined amount corresponding to a shift amount between the two-stage drive gears. 2. A boss portion is provided so as to project toward a drive gear side at substantially the center of the reel on the other side in the thickness direction of the cartridge body, and the center of the reel on one side in the thickness direction of the cartridge body is approximately at the center. The recess is formed in at least one of the outer peripheral surface of the boss portion and the inner peripheral surface of the through hole, and the recess portion is loosely inserted in the through hole provided in the. Magnetic recording medium cartridge.