JPH08315539A - Reel for magnetic tape cassette - Google Patents

Abstract

PURPOSE: To protect a reel against contamination and to protect a magnetic tape against damage. CONSTITUTION: A tooth 15 is provided on the outer circumference of a lower flange 13 and the inner surface 16 is set higher than the upper end face 17 of the tooth 15. The edge 18 on the outer circumference of inner surface 16 is formed with a radius of curvature R within a predetermined range. In the embodiment, the radius of curvature R is set in the range of 1-4mm, preferably, in the range of 1.5-3mm. Since the radius of curvature R is not too large, a magnetic tape 2 is prevented from touching the upper end face 17 of the tooth 15 to be scrubbed locally. Furthermore, since the radius of curvature R is not too small, the magnetic tape 2 is prevented from being scrubbed locally by the edge 18. With such structure, a magnetic body is prevented from being stripped to cause contamination of a reel or to cause damage on the magnetic tape 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reel for a magnetic tape cassette, and more particularly to a high density magnetic tape having flanges on the upper and lower ends of a tape winding surface, and a magnetic tape cassette for business use in which the tape winding diameter is large. The present invention relates to a magnetic tape cassette reel suitable for use in, for example,

[0002]

2. Description of the Related Art Conventionally, there are various types of magnetic tape cassettes used in VTRs (video tape recorders) and the like, but a pair of reels for magnetic tape cassettes are usually provided in this magnetic tape cassette. It is magnetically wrapped and stored rotatably. As shown in FIG. 3, the reel 40 for the magnetic tape cassette is a cylindrical tape winding body portion 4 around which the magnetic tape 102 is wound, as is well known.
Upper and lower flanges 44 and 100 are provided above and below the unit 1. In many cases, the lower flange 100 is integrally formed with the tape winding body 41, while the upper flange 44 is separately formed and attached to the upper end of the tape winding body 41 by welding, fitting, or the like. There is. This is because the upper and lower flanges 44, 100 are made of different materials, as will be described next.

That is, the lower flange 100 is engaged with the reel brake means on the outer peripheral edge thereof, the rotation driving shaft of the VTR is engaged with the engagement hole at the center thereof, and the center portion of the upper end thereof is Mechanical strength is required for the reason that a leaf spring provided on the magnetic tape cassette for urging the reel for the magnetic tape cassette is engaged with the magnetic tape cassette. Therefore, for example, polyoxymethylene (POM) or It is integrally molded with resin such as high-impact polystyrene (HIPS).

On the other hand, the upper flange 44 is not required to have the same strength as the lower flange, and the winding state of the magnetic tape needs to be light-transmitting so that it can be seen from the outside of the cassette. Therefore, it is formed of a material different from that of the lower flange, such as acrylonitrile / styrene copolymer (AS) or general-purpose polystyrene (GPPS), which is relatively inexpensive to manufacture.

[0005]

By the way, as shown in FIG. 4, the lower flange 100 of the conventional magnetic tape cassette reel 40 is provided with teeth 101 for engaging the reel brake means on the entire outer circumference. ing. Inner surface 103 of lower flange 100 that contacts magnetic tape 102
Has a step (protruded in the figure) having a step protruding from the upper end surface of the tooth 101 toward the upper flange side. Then, the edge 104 on the outer peripheral side of the inner surface 103 has a radius of curvature R in a cross section in a plane passing through the rotation center axis of the reel 40 (hereinafter, this radius of curvature is simply referred to as “curvature radius R”). Usually, it is formed with a thickness of about 0.2 mm.

On the other hand, in a video tape cassette or the like, the VT
In the state of being loaded in the R, the magnetic tape 102 is in a state of being largely pulled out of the cassette. Therefore, particularly when the tape running speed is high such as when the magnetic tape 102 is unwound or wound up, A problem was caused by the tape 102 swinging in the tape width direction (up and down in the drawing). That is, when the magnetic tape 102 swings to the lower side (lower flange side), the lower edge 105 of the magnetic tape 102 contacts the edge 104 of the lower flange 100.
At this time, conventionally, the radius of curvature R of the edge 104 is as small as about 0.2 mm as described above, so the lower edge 105 of the magnetic tape 102 is rubbed by the edge 104 and the magnetic force applied to the magnetic tape 102 is reduced. There is a risk that the body may fall off, or the magnetic tape 102 itself may be damaged together with its base.

Therefore, it can be inferred that the above problem can be solved by increasing the radius of curvature of the edge 104, for example, 6 to 10 mm. However, this curvature is actually increased, and furthermore, the inner surface 103 of the edge 104 is made larger. Even if it is configured with a continuous inclined surface so that there is no step toward the end, the problem is not solved so much, on the contrary, the magnetic tape 1
The damage of 02 etc. became severe. Particularly, in recent years, the tape transport speed at the time of fast-forwarding or rewinding the magnetic tape of the magnetic tape cassette has been increasing more and more, and this kind of problem has become serious. In addition, since high density recording has been achieved in recent years,
Since a dropout is induced by even a slight drop of the magnetic material, this kind of problem has become an extremely serious problem in cassette performance.

The present invention has been made in view of the above problems, and provides a reel for a magnetic tape cassette capable of preventing the magnetic body of the magnetic tape from falling off or damaging the magnetic tape itself. The purpose is.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above problems, and have found a solution to the problems. That is, the object of the present invention is to provide a cylindrical tape winding surface around which a magnetic tape is wound, upper and lower flanges on the upper and lower ends of the tape winding surface, and teeth on the outer periphery of the lower flange. In the reel for magnetic tape cassette, the inner surface other than the teeth of the lower flange is configured to protrude toward the upper flange side from the end surface of the teeth, and further, the rotation of the reel at the outer peripheral edge of the inner surface other than the teeth. The radius of curvature in a cross section on a plane passing through the central axis is 1 to 4 m
It is achieved by a reel for a magnetic tape cassette characterized by being in the range of m.

As a more preferred embodiment of the present invention, the radius of curvature of the outer peripheral edge is in the range of 1.5 to 3 mm.

[0011]

In the reel for magnetic tape cassette of the present invention, the outer peripheral edge of the inner surface other than the teeth of the lower flange is formed with a radius of curvature R in a specific range of 1 to 4 mm, more preferably 1.5 to 3 mm. Therefore, at the lower limit of this value, even if the magnetic tape swings downward and contacts the outer peripheral edge of the inner surface, it is possible to avoid local rubbing by only rubbing in a wider range than before. Exerts an action,
In addition to this, at the upper limit of the numerical value, it is possible to avoid allowing contact between the magnetic tape edge and the tooth edge by approaching the inclined structure so as to eliminate the step at the outer peripheral edge portion. It is presumed that it can exhibit.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a magnetic tape cassette reel according to the present invention will be described below with reference to FIGS. FIG. 1 is an enlarged cross-sectional view of a main part (portion A in FIG. 2) of a magnetic tape cassette reel according to the present invention, and FIG. 2 is a main-part cross-sectional view of a magnetic tape cassette equipped with a magnetic tape cassette reel according to the present invention. is there. For convenience of description, first, the overall structure of the magnetic tape cassette and the reel for the magnetic tape cassette will be described with reference to FIG. 2, and then the lower flange will be described with reference to FIG.

As shown in FIG. 2, a magnetic tape cassette 200 having a pair of magnetic tape cassette reels 1 according to the present invention is a rotary drive shaft of a recording / reproducing apparatus corresponding to the magnetic tape cassette reel 1 on the bottom surface of the cassette. An opening 203 for inserting the magnetic tape 2 is provided on the front side of the cassette.
10 is provided with a guard panel 201 that can open and close a front opening 204 that can be pulled out by a guide pin that forms a tape path. The magnetic tape cassette reel 1 is provided with a cylindrical tape winding body portion 11 (core portion) around which the magnetic tape 2 is wound, and a rotary drive shaft (not shown) such as a VTR is provided in the center portion thereof. A mating engagement hole 12 is provided. A lower flange 13 is integrally formed on the lower end of the tape winding body 11. On the other hand, at the upper end of the tape winding body portion 11, a separately formed transparent upper flange 14 is formed.
Is stuck. The magnetic tape 2 is normally wound so that the lower end thereof abuts the inner surface 16 of the lower flange 13 as shown in the drawing, and a slight gap is formed between the upper flange 14 and the magnetic tape 2.

As shown in FIG. 1, teeth 15 for engaging a reel brake mechanism (not shown) of the VTR are provided on the outer circumference of the lower flange 13 over the entire circumference. The above-mentioned structure is the same as the conventional one, but the characteristic structure of the magnetic tape cassette reel 1 according to the present invention is that the inner surface 16 of the lower flange 13 against which the magnetic tape 2 abuts, as shown in FIG.
Is higher than the upper end surface 17 of the tooth 15 with a step, and the edge 18 on the outer peripheral side of the inner surface 16 of the lower flange 13 is
Are formed with a radius of curvature R within a predetermined range. In the present embodiment, the radius of curvature R is set to 1 to 4 mm, and preferably the radius of curvature R is set to 1.5 to 3 mm.

By thus forming the edge 18 of the inner surface 16 of the lower flange 13 with a radius of curvature R in a predetermined range, the magnetic tape 2 is swung up and down to be unwound or wound, as will be described below. Even when the magnetic tape 2 is removed, it is possible to prevent the magnetic material applied to the magnetic tape 2 from being peeled off or the magnetic tape 2 itself from being damaged.

Next, when a pair of tape reels is used in the magnetic tape cassette 200, the magnetic tape 2 is unwound on nine types of reels in which the radius of curvature R of the edge 18 is changed in the range of 0 to 5.0 mm. The results of observing how the magnetic tape 2 is damaged and the inner surface of the magnetic tape cassette reel 1 being soiled and the magnetic tape 2 being damaged are shown. The other specifications of the tape reel are as follows. The tape winding surface has a height of 13.3 mm and a diameter of 36 mm, and the upper and lower flanges have a diameter of 122.5 mm.
The length of the lower flange tooth in the radial direction of the reel is 0.5 mm
And the step between the upper surface of the tooth and the inner surface of the lower flange is 0.2m.
m. In this test, after performing fast forward (FF) and winding (REW) 1000 times, stains on the lower flange 13 of the reel and physical damage on the lower end of the magnetic tape were visually observed and evaluated according to the following criteria. . Practically acceptable are A and B. The results are shown in Table 1. Regarding each evaluation in Table 1, A is "the bottom flange is completely free of dirt and the lower end of the magnetic tape is not damaged.", B is "the outer edge of the lower flange is partially dirty, but the bottom end of the tape is damaged. No. ", C" The outer edge of the lower flange is dirty all around, but the bottom edge of the tape is not damaged. ", D is" The outer edge of the lower flange is all around, and the bottom edge of the tape is damaged. Damage was also found. "
Was used as the criterion.

[0017]

[Table 1]

As can be seen from Table 1, when the radius of curvature R of the edge 18 was 5.0 mm, no tape damage was observed, but the outer circumference of the lower flange was dirty over the entire circumference. If the radius of curvature R is too large in this way, the edge 18 becomes close to a tapered surface, and the lower flange 13
Perhaps this is the result of the magnetic tape 2 coming into contact with the edge of the upper end surface 17 of the tooth 15 of this, and this causes the magnetic tape 2 to be locally rubbed and the magnetic substance peeled off, and this magnetic substance adheres to the reel and becomes dirty. Is considered to have occurred.

When the radius of curvature R = 4.0 mm, the outer peripheral edge of the lower flange was slightly soiled, and no tape damage was observed. Radius of curvature R =
In the case of 3.0 mm and the radius of curvature R = 1.5 mm, the outer circumference of the lower flange was not contaminated at all and no tape damage was observed. When the radius of curvature R was 1.0 mm, the outer peripheral edge of the lower flange was only partially soiled, and no tape damage was observed. From this, when the radius of curvature R = 1.0 to 4.0 mm, it is not too large as in the case of the radius of curvature R = 5.0 mm, so that the magnetic tape 2 does not contact the edge of the tooth 15. Moreover, since it is not too small, the magnetic tape 2 is not locally rubbed, and therefore it is considered that the outer peripheral edge of the lower flange has no stain or a small amount, and the tape is not damaged. In particular, when the radius of curvature R was 1.5 to 3.0 mm, there were no stains on the outer peripheral edge of the lower flange and no tape damage, and very favorable results were obtained.

When the radius of curvature R = 0.5 mm or 0.3 mm, the outer peripheral edge of the lower flange was soiled over the entire circumference. Thus, when the radius of curvature R becomes smaller,
The magnetic tape 2 is locally rubbed and the magnetic material is peeled off,
It is considered that the magnetic tape 2 itself is damaged. Radius of curvature R
= 0.2 mm and a radius of curvature R = 0 mm, the outer edge of the lower flange was heavily soiled and the tape was damaged. Therefore, the radius of curvature R = 0.5
If it is less than mm, it is not suitable for practical use.

From this test result, the radius of curvature R = 1.0
.About.40 mm is judged to be suitable for practical use, and the radius of curvature R = 1.5 to 3.0 mm is more preferable. As described above, the reel 1 for the magnetic tape cassette of the present invention
Since it can prevent reel dirt and tape damage, it is particularly suitable for a high-density magnetic tape coated with a large amount of magnetic material and a commercial magnetic tape cassette reel in which the winding diameter of the magnetic tape 2 becomes large. There is.

[0022]

As described above, in the reel for magnetic tape cassette of the present invention, the outer peripheral edge of the inner surface of the lower flange has a radius of curvature in the range of 1 to 4 mm, preferably 1.5 to 3 m.
Since it is formed with a radius of curvature of a specific range, that is, a radius of curvature of m, local rubbing of the tape edge of the magnetic tape by the outer peripheral edge or the teeth is avoided along with the behavior change of the magnetic tape swinging up and down, As a result, the magnetic material applied to the magnetic tape does not fall off or peel off, and it is possible to prevent the reel from becoming dirty and the edge of the magnetic tape from being damaged.

[Brief description of drawings]

FIG. 1 is an enlarged view showing an outer peripheral portion of a lower flange of a reel for a magnetic tape cassette according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a magnetic tape cassette reel.

FIG. 3 is a cross-sectional view of a conventional magnetic tape cassette reel.

FIG. 4 is an enlarged view of an outer peripheral portion of a lower flange in a conventional magnetic tape cassette reel.

[Explanation of symbols]

 1 Magnetic Tape Cassette Reel 2,102 Magnetic Tape 13,100 Lower Flange 14 Upper Flange 15,101 Teeth 16,103 Inner Surface 18,104 Edge 200 Magnetic Tape Cassette

Claims (1)

[Claims] 1. A magnetic tape cassette having a cylindrical tape winding surface around which a magnetic tape is wound, upper and lower flanges provided at the upper and lower ends of the tape winding surface, and teeth provided on the outer periphery of the lower flange. In the reel, the inner surface other than the teeth of the lower flange is configured to project toward the upper flange side from the end surface of the teeth, and further passes the rotation center axis of the reel at the outer peripheral edge of the inner surface other than the teeth. A magnetic tape cassette reel having a radius of curvature in a plane section of 1 to 4 mm.