JP2000003577A - Magnetic tape cassette and driving device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic tape cassette and a driving device therefor which can reduce defects in linearity. SOLUTION: This cassette and driving device therefor is provided with a hub 1 of a hollow cylindrical type on which a magnetic tape is wound and a reel for a magnetic tape of which upper and lower flanges are provided at the upper and lower ends of the hub 1, and engaging with the hub 1, the reel for magnetic tape is driven to rotate by a driving shaft 2. In this case, the difference between a radius R of the hub 1 and a radius(r) of the driving shaft 2 is 50 μm or more to less than 200 μm, out of roundness of the hub 1, that is, the difference between radiuses (R-R') and out of roundness of the driving shaft 2, that is, the difference between radiuses (r-r') are both set to 20 μm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape cassette and a driving device therefor. More specifically, the present invention relates to a magnetic tape cassette in which a magnetic tape reel having upper and lower flanges at upper and lower ends of a hub around which a magnetic tape is wound is accommodated in a cassette case, and a driving device therefor.

[0002]

2. Description of the Related Art Conventionally, there are various types of magnetic tape cassettes used for a video tape recorder (hereinafter, simply referred to as "VTR") and the like. A magnetic reel is wound around a magnetic tape and is rotatably housed.

FIG. 2 shows the basic structure of the magnetic tape reel 20 described above. As shown in FIG. 2, the magnetic tape reel 20 is a hollow cylindrical hub 2 around which a magnetic tape is wound.
2, a disk-shaped upper flange 24 fixed to the upper end of the hub 22, and a disk-shaped lower flange 25 integrally formed at the lower end of the hub 22.

The hollow cylindrical hub 22 is provided with engaging teeth 22a for engaging with a reel drive shaft in the hollow circle, and has an upper end engaged with a reel spring provided in a cassette case. And a welding boss 22c for positioning the upper flange 24 are provided. Also,
The upper flange 24 and the lower flange 25 protect the tape by preventing the magnetic tape from being distorted or distorted, and by preventing damage to the tape edge and the like.

[0005]

In recent years, with the digitization and miniaturization of magnetic recording apparatuses, the recording density has been improved in order to record enormous information data in a small space. In view of this, tape layers have been made thinner to improve the volume recording density of the magnetic tape wound around the above-described magnetic tape reel 20, and narrower tracks have been made to improve the surface recording density. However, if the tape is made thinner, the tape is easily deformed, and if the track is made narrower, even if the tape is slightly deformed, if the recording signal is partially bent, the output of that part will be lower than the linear part during reproduction. That is, a so-called linearity defect easily occurs.

When the tape is deformed, the tape comes into strong contact with a guide roller or the like during high-speed running or acceleration / deceleration in the VTR, and appears as locally strong weaving. Here, when recording / reproducing is performed in the tape deformed portion, the output fluctuates due to linearity failure.

[0007] In view of such circumstances, an object of the present invention is to provide a magnetic tape cassette capable of reducing linearity defects and a drive device therefor.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a hollow cylindrical hub on which a magnetic tape is wound and a magnetic tape reel having upper and lower flanges at the upper and lower ends of the hub. A magnetic tape cassette and a driving device for rotating the magnetic tape reel by a driving shaft while being engaged with the hub, wherein a difference between a radius of the hub and a radius of the driving shaft is 50 μm or more and less than 200 μm; The magnetic tape cassette is characterized in that both the circularity, ie, the radius difference, and the circularity, ie, the radius difference of the driving shaft provided in the driving device, are set to 20 μm or less, and a driving device for the magnetic tape cassette is provided.

According to the present invention, for example, a magnetic tape reel on which a magnetic tape is wound has a hub diameter of 14.0 to 14.
When the distance is within the range of 1 mm, the difference between the radius of the hub and the radius of the drive shaft that rotationally drives the hub is 50 μm or more and
The magnetic tape wound around the hub is set to be less than 0 μm, and the roundness of the hub, that is, the radius difference, and the circularity, that is, the radius difference of the drive shaft are both set to 20 μm or less to form a substantially circular shape. The vertical movement of the tape is suppressed, the tape is hardly deformed, and the upper winding hardness can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram of a magnetic tape reel of a magnetic tape cassette and a drive shaft of a VTR according to an embodiment of the present invention.

A magnetic tape reel according to an embodiment of the present invention also has a hollow cylindrical hub on which a magnetic tape is wound and upper and lower flanges at upper and lower ends of the hub, similarly to the conventional example shown in FIG. Is provided. And, as shown in FIG.
The magnetic tape reel 1 is rotatably driven by a drive shaft 2 by engaging with the hollow circle 1 a of the hub 1.

The magnetic tape reel of the present invention has a hub diameter in a range of 14.0 to 14.1 mm, and a difference between a radius R of the hub 1 and a radius r of the drive shaft 2 is 50 μm to 200 μm.
Is set to less than. Furthermore, the difference (roundness) between the radius R of the hub 1 and the radius R 'on the diagonal is set to 20 μm or less, so that the hub 1 has a substantially perfect circle, and is substantially diagonal to the radius r of the drive shaft. Is also substantially round because the difference (roundness) from the radius r ′ of the is set at 20 μm or less. It will be apparent from the following examples that by setting to such a value, the vertical movement of the magnetic tape wound around the hub 1 is suppressed, the tape is unlikely to be deformed, and the winding rigidity can be improved.

[0013]

EXAMPLES Using Examples 1 to 3 and Comparative Examples 1 to 4, experiments were conducted on the output fluctuation and the hardness of the magnetic tape reel. If the output fluctuation after data storage is 50% or less, the test is passed, and if the hardness after FF / REW is 1 kg or more, the test is passed. The differences between the hub radius and the drive shaft radius, the hub roundness or radius difference, and the drive shaft itself roundness or radius difference shown in Examples 1 to 3 and Comparative Examples 1 to 4 are as shown in Table 1. is there.

[0014]

[Table 1]

As is clear from Table 1, in the case of the first embodiment, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 is 60 μm.
m, and the roundness of the hub 1, that is, the radius difference (R-R ′) is 1
5 μm, and the circularity of the drive shaft 2, that is, the radius difference (r−
r ′) is 5 μm. In this case, it can be seen that the output fluctuation after storage is as small as 20% which is 50% or less, and the winding hardness after FF / REW is 1.0 kg or more and 1.2 kg. Therefore, according to Example 1, it was found that the vertical movement of the magnetic tape was suppressed, the tape was less likely to be deformed, and the winding hardness could be improved.

In the case of the second embodiment, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 is 180 μm, the radius difference (R-R ′) of the hub 1 is 5 μm, and the drive shaft 2 Has a radius difference (rr ′) of 18 μm. In this case, it can be seen that the output fluctuation after storage is as small as 30% which is 50% or less, and the winding hardness after FF / REW is 1.0 kg or more and 1.8 kg. Therefore, it was also found that in Example 2, the vertical movement of the magnetic tape was suppressed, the tape was hardly deformed, and the winding hardness could be improved.

In the case of the third embodiment, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 is 120 μm, the radius difference (R−R ′) of the hub 1 is 18 μm, and the drive shaft 2 Has a radius difference (rr ′) of 15 μm. In this case, it can be seen that the output fluctuation after storage is 50% or less and 40%, and the stiffness after FF / REW is 1.0 kg or more and 1.5 kg. Therefore, according to the third embodiment, it was found that the vertical movement of the magnetic tape was suppressed, the tape was hardly deformed, and the winding hardness could be improved.

On the other hand, in the case of Comparative Example 1, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 is 30 μm, which is 50 μm or less, and the radius difference (R−R ′) of the hub 1 is 15μ
m, and the radius difference (rr ′) of the drive shaft 2 is 5 μm. In this case, the output fluctuation after storage is 15% which is 50% or less.
However, it can be seen that the hardness after FF / REW is 0.8 kg, which is 1.0 kg or less. Therefore, according to the comparative example 1, although the vertical movement of the magnetic tape is suppressed,
It has been found that if the value of r is as small as 30 μm, the winding hardness cannot be improved.

In the case of Comparative Example 2, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 is 250 μm, the radius difference (R−R ′) of the hub 1 is 5 μm, and the drive shaft 2 Has a radius difference (rr ′) of 18 μm. In this case, FF / RE
The roll hardness after W is 1.0 kg or more and 2.0 kg,
It can be seen that the output fluctuation after storage is 55% or more than 50%. Therefore, according to Comparative Example 1, it was found that the hardness of the magnetic tape could be improved, but if the value of R-r was as large as 250 μm, the vertical movement of the magnetic tape was not suppressed.

In the case of Comparative Example 3, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 is 60 μm, the radius difference (R-R ′) of the hub 1 is 25 μm, and the drive shaft 2 Has a radius difference (rr ′) of 5 μm. In this case, FF / REW
It can be seen that the hardness after winding is 1.0 kg or more and 1.3 kg, and the output fluctuation after storage is 50% or more and 60%.
Therefore, according to Comparative Example 3, it was found that the hardness of the magnetic tape could be improved, but if RR ′ was as large as 25 μm, the vertical movement was not suppressed.

In the case of Comparative Example 4, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 is 180 μm, the radius difference (R−R ′) of the hub 1 is 5 μm, and the drive shaft 2 Has a radius difference (rr ′) of 30 μm. In this case, FF / RE
The winding hardness after W is 1.9 kg, which is 1.0 kg or more,
It can be seen that the output fluctuation after storage is 50% or more and 75%. Therefore, according to Comparative Example 4, although it was possible to improve the hardness of the magnetic tape, it was found that if rr ′ was as large as 30 μm, the vertical movement was not suppressed.

As described above, Examples 1 to 3 and Comparative Example 1
Taking into account the experimental results based on the above-mentioned conditions, the difference between the radius R of the hub 1 and the radius r of the drive shaft 2 specified in the present invention is 50 μm.
And less than 200 μm, and the difference in radius of the hub 1 (R−
R ′) and the radius difference (rr ′) of the drive shaft 2 are both 20 μm.
It has been found that good experimental results can be obtained if the following conditions are satisfied. Here, the above-described embodiment is preferably applied to a commercial D3 system or a D5HD system.

It should be noted that the present invention is not limited to the above-described embodiment, but can be appropriately changed and improved based on the gist of the present invention. That is, if the hub diameter of the magnetic tape reel is changed from the above-described embodiment, if the above-described value is appropriately changed and set accordingly, the vertical movement of the magnetic tape can be suppressed, and the winding hardness can be improved. be able to. In this case, the present invention can be applied not to the D3 system or the D5HD system but to another recording apparatus.

[0024]

As described above, according to the present invention, the difference between the radius of the hub and the radius of the drive shaft is not less than 50 μm and less than 200 μm, and the circularity of the hub, that is, the difference in radius and the perfect circle of the drive shaft. Since both the degrees, that is, the radius differences are set to 20 μm or less, the vertical movement of the magnetic tape wound around the hub is suppressed, the tape hardly deforms, and the winding hardness can be improved. Therefore,
Output fluctuations due to poor linearity can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a magnetic tape reel of a magnetic tape cassette and a drive shaft of a VTR according to an embodiment of the present invention.

FIG. 2 shows a basic structure of a conventional magnetic tape reel.

[Explanation of symbols]

 1 hub 2 drive shaft

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Sugawara 2-12-1, Ogimachi, Odawara City, Kanagawa Prefecture Inside Fuji Photo Film Co., Ltd. (72) Inventor Mitsugu Yamagishi 2-12-1, Ogimachi, Odawara City, Kanagawa Prefecture Inside Fuji Photo Film Co., Ltd. (72) Inventor Junji Asada 2--12-1, Ogimachi, Odawara-shi, Kanagawa Prefecture Inside Fuji Photo Film Co., Ltd. (72) Mikio Ohno 2-12-1, Ogimachi, Odawara-shi, Kanagawa Prefecture Fuji Photo Film Co., Ltd. F-term (reference) 5D071 AA07 AA15 CC20

Claims (1)

[Claims] 1. A magnetic tape reel comprising: a hollow cylindrical hub on which a magnetic tape is wound; and a magnetic tape reel having upper and lower flanges provided at upper and lower ends of the hub, wherein the magnetic tape reel is engaged in the hub. A magnetic tape cassette and a drive device for rotating the drive shaft by a drive shaft, wherein the difference between the radius of the hub and the radius of the drive shaft is 50 μm or more and less than 200 μm, the circularity of the hub, that is, the radius difference, and the drive device And a drive device for the magnetic tape cassette, wherein both the circularity, that is, the radius difference of the drive shaft provided in the magnetic tape cassette is 20 μm or less.