JPH0594688A - Hub of tape cassette - Google Patents

Abstract

PURPOSE:To prevent from losing a function of a tape cassette by smoothly being engaged with a hub driving shaft of a tape driving mechanism in the hub incorporated in the tape cassette, even though a shrinkage in the inner circumferential direction generates with winding pressure of a magnetic tape due to deterioration of rigidity of a resin at time of storage in high temp. CONSTITUTION:The hub 3 is constituted with an outer peripheral part 3a on which the magnetic tape 2 is wound, an inner peripheral part 3b being engaged with the hub driving shaft of the tape driving mechanism, and a thin thickness of connection part 3c connecting the outer peripheral part 3a and the inner peripheral part 3b. Even though the outer peripheral part 3a shrinks in the inner circumferential direction with the winding pressure of the magnetic tape 2 at high temp., the shrinkage is absorbed by deformation of the thin thickness of connection part 3c, and it is not transmitted to the inner peripheral part 3b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hub incorporated in a tape cassette.

[0002]

2. Description of the Related Art First, a conventional example will be described with reference to FIGS. In FIG. 2, reference numeral 1 denotes a tape cassette (compact cassette for audio), and a pair of hubs 3 around which a magnetic tape 2 is wound are rotatably accommodated in the tape cassette 1. This hub 3 has a central hole 4 as shown in FIG.
Is formed in a ring shape having a plurality of engaging projections 5 on its inner peripheral surface. The hub 3 is arranged corresponding to the hub drive shaft insertion hole 6 formed in the upper and lower surfaces of the tape cassette 1. The magnetic tape 2 wound around the hub 3 is led out and exposed to the front opening 7 through a predetermined tape guide portion in the tape cassette, and corresponds to a magnetic head or the like of a tape drive mechanism described later. Further, a portion forming the front opening 7 has a trapezoidal bulge 8 which bulges vertically.
The bulging portion 8 has a positioning reference hole 9 and a capstan insertion hole 10.

On the other hand, 11 is a tape drive mechanism of a cassette tape recorder, 12 is a hub drive shaft, 13 is a positioning reference pin, 14 is a capstan, 15 is a magnetic head for recording / reproducing, 16 is a magnetic head for erasing, and 17 is a magnetic head. It is a pinch roller. When the tape cassette 1 is attached to the tape drive mechanism 11, the reference pin 12 is inserted into the reference hole 9 for positioning, and at the same time, the hub drive shaft 12 is inserted into the tape cassette through the hub drive shaft insertion hole 6. Center hole 4 of hub 3
And the capstan 14 is inserted into the capstan insertion hole 10.

When the tape cassette 1 is completely attached to the tape drive mechanism 11 in this manner, the magnetic heads 15 and 16 and the pinch roller 17 are advanced and inserted into the front opening 7, and the magnetic heads 15 and 16 are connected to the magnetic tape. In contact with each other, the pinch roller 17 is pressed against the capstan 14 while sandwiching the magnetic tape. In this state, the hub drive shaft 12 and the capstan 14 are rotationally driven, so that the running operation of the magnetic tape is performed. A plurality of engagement claws 12a are formed on the peripheral surface of the hub drive shaft 12, and the engagement claws 12a are engaged with the engagement protrusions 5 of the hub 3 in the rotational direction, so that the hub drive shaft 12 is fixed. The following rotation of the hub 3 is performed.

[0005]

FIG. 3 shows the dimensional relationship between the hub 3 of the tape cassette and the hub drive shaft 12 of the tape drive mechanism. That is, the diameter of the hub drive shaft 12 including the engaging claws 12a (rotational diameter of the hub drive shaft 12) a ₁ and the hub 3
The inner diameter b ₁ of the center hole 4 is a ₁ <b ₁ , the engaging claw 12
The relationship between the diameter a _{2 of the} main body of the hub drive shaft 12 that does not include a and the distance b ₂ between the opposing engagement projections 5 of the hub 3 is a ₂ <b
₂ , the hub drive shaft 12 is smoothly engaged with the hub 3 in a normal state. However, if the tape cassette is stored at a high temperature for a long time, the hub 3 may contract in the inner peripheral direction, which may not be smoothly engaged with the hub drive shaft 12. This is because hub 3 is generally PO
This is because it is formed of a resin material such as M and the winding pressure of the magnetic tape 2 is applied to the hub 3 when the rigidity of the resin material is reduced by heat. When the hub 3 contracts, as shown in FIG. 4A, the hub 3 cannot be engaged with the hub drive shaft 12 and the tape cassette cannot be mounted. As shown in FIG. B, the hub 3 tightens the hub drive shaft 12 and the tape cassette cannot be taken out.

The present invention has been made in view of the above points,
An object of the present invention is to provide a hub structure that does not prevent the tape cassette from being attached or detached even when contraction occurs due to tape winding pressure.

[0007]

To achieve the above object, a hub of the present invention comprises an outer peripheral portion around which a tape is wound, an inner peripheral portion engaged with a hub drive shaft of a tape drive mechanism, It is configured by a thin connecting portion that connects the outer peripheral portion and the inner peripheral portion.

[0008]

In the hub of the present invention constructed as described above, even if the outer peripheral portion contracts due to the winding pressure of the tape during high temperature storage, this contraction is absorbed by the thin connecting portion being crushed, and the inner peripheral portion I don't get it. Therefore, since the inner peripheral portion does not contract, the hub is always smoothly engaged with the hub drive shaft of the tape drive mechanism, and the tape cassette is not detachable.

[0009]

Embodiments of the present invention will be described below with reference to FIG. Hub 3 of tape cassette according to the invention
Is characterized by having a three-step structure in the radial direction as is clear from the drawing. That is, the hub 3 of this example includes the outer peripheral portion 3a, the inner peripheral portion 3b, and the outer peripheral portion 3a and the inner peripheral portion 3a.
and a thin connecting portion 3c for connecting b.

The outer peripheral portion 3a has a magnetic tape 2 on its peripheral surface.
On the other hand, the inner peripheral portion 3b has a central hole 4 at the center thereof into which the hub drive shaft 12 of the tape drive mechanism 11 is inserted and engaged, and the inner peripheral surface of the central hole 4 has the aforementioned Engagement protrusions 5 that engage with the engagement claws 12 a of the hub drive shaft 12 are formed. The thin connecting portion 3c connects and connects the outer peripheral portion 3a and the inner peripheral portion 3b at the central portion, and its cross section is formed in a bellows shape bent in a V shape. In this example, the thin connecting portion 3c is formed continuously over the entire circumference of the hub 3.

In the hub 3 of the present embodiment thus constructed, when the rigidity of the resin decreases during high temperature storage, the outer peripheral portion 3a contracts due to the winding pressure of the magnetic tape 2 (see FIG. 1B). At this time, the connecting portion 3c functions as a cushioning portion to stop the contraction, so that the inner peripheral portion 3b does not contract. That is, since the connecting portion 3c is thin and has a shape bent in advance in a V shape, the connecting portion 3c is easily crushed by contraction of the outer peripheral portion 3a, and thus the contraction of the outer peripheral portion 3a is not transmitted to the inner peripheral portion 3b.

Therefore, even if the dimension of the outer peripheral portion 3a changes due to the contraction of the magnetic tape 2 due to the winding pressure, the dimension of the inner peripheral portion 3b does not change, that is, as shown in FIG. inner diameter c ₁ of the inner peripheral portion 3b of a), the outer diameter d _1,
Inner diameter e ₁ and outer diameter f _{1 of} the outer peripheral portion 3 a, inner diameter c ₂ of the inner peripheral portion 3 b after contraction of the hub (the same figure B), outer diameter d _{2 of the} same, inner diameter dimension of the outer peripheral portion 3 a e ₂ , same outer diameter f ₂
The relationship with c ₁ = c ₂ , d ₁ = d ₂ , e ₁ > e ₂ , f
₁ > f ₂ , so that when the tape cassette is mounted on the cassette tape recorder, the hub 3 smoothly engages with the hub drive shaft, and even when the hub 3 contracts in the cassette tape recorder, the hub 3 will be The tape cassette can be taken out from the hub drive shaft easily without any trouble.

In the structure of the hub of the present embodiment, if the thickness g of the connecting portion 3c is too thin, the connection between the outer peripheral portion 3a and the inner peripheral portion 3b is poor, and if it is too thick, the contraction of the outer peripheral portion 3a is absorbed. Since the effect becomes thin (hard to be crushed), the outer peripheral portion 3
It is desirable to set it to about 1/3 to 1/4 of the thickness h of a.

As described above, according to the hub of this embodiment, even if the magnetic tape 2 is shrunk due to the winding pressure during high temperature storage, the shrinkage is absorbed by the thin connecting portion 3c, so that the inner diameter of the hub 3 is reduced. Since it is maintained, normal use is always possible without losing the function of the tape cassette. Further, as a material of the hub 3, an inexpensive resin material such as HI-PS, which has been conventionally unusable because of its high shrinkage ratio, can be used, which greatly contributes to cost reduction. ..

In the structure of this embodiment, the thin connecting portion 3c for connecting the outer peripheral portion 3a and the inner peripheral portion 3b does not have to be continuously formed over the entire circumference of the hub 3, but the outer peripheral portion 3a and the inner peripheral portion 3b. It may be partially formed in consideration of connectivity, strength, etc. of 3b. Further, the present invention is not limited to the hub of the audio compact cassette as shown in the drawing, but it is needless to say that the present invention can be widely applied to hubs of all kinds of tape cassettes such as so-called micro cassettes, video cassettes, and DAT cassettes. ..

[0016]

As described above, the hub of the present invention is
Since the tape is wound around the outer peripheral portion, the inner peripheral portion that is engaged with the hub drive shaft of the tape drive mechanism, and the thin connecting portion that connects the outer peripheral portion and the inner peripheral portion, Even if shrinkage occurs due to the winding pressure of the tape, this shrinkage is absorbed by the thin-walled connection portion being crushed and is not transmitted to the inner peripheral portion. Therefore, when the tape cassette is attached and detached, the hub is always smoothly engaged with and disengaged from the hub drive shaft, and the tape cassette can reliably maintain its function.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a hub showing an embodiment, where A is a state before contraction and B is a state after contraction.

FIG. 2 is an explanatory diagram of a tape cassette and a tape drive mechanism.

FIG. 3 is an explanatory diagram of a conventional hub.

FIG. 4 is an explanatory view of a problem of the conventional hub, where A is a state in which the hub contracts and cannot engage with the hub drive shaft, and B is a state in which the hub cannot be disengaged from the hub drive shaft.

[Explanation of symbols]

 1 tape cassette 2 magnetic tape 3 hub 3a outer peripheral part 3b inner peripheral part 3c connecting part 11 tape drive mechanism 12 hub drive shaft

Claims (1)

[Claims] 1. A hub built in a tape cassette, wherein an outer peripheral portion around which a tape is wound, an inner peripheral portion engaged with a hub drive shaft of a tape drive mechanism, and the outer peripheral portion and the inner peripheral portion. Hub of the tape cassette consisting of a thin connecting part that connects