Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system
Reexamination Certificate
1998-09-10
2001-11-06
Darling, John P. (Department: 3653)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
Cartridge system
C242S610600, C242S611200, C242S613400
Reexamination Certificate
active
06311917
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tape reel for a tape cassette, such as a VHS cassette or 8 mm video cassette, that holds within its housing a pair of reels around which a length of tape is wound.
2. Description of the Prior Art
Contrivances for making tape reels as light as possible, while reducing the distortion due to uneven curing of the resin at the time of molding and minimizing the sacrifice of strength, have been proposed in prior art documents, for example, by Japanese Patent Application Kokai No. 55-87352.
FIGS. 7 and 8
in the accompanying drawings illustrate an embodiment of the invention described in the specification of the above application. A tape reel
55
is shown comprising a hub which consists of a central drum
62
formed in one piece with, or solidly joined to, a lower flange
72
, and an upper flange
73
fixed to the hub, with a spring (
8
in
FIG. 1
) pressing a center boss
54
at the top of the central drum
62
in place. The central drum
62
consists of an outer cylindrical part
71
on which a tape is wound and an inner cylindrical part
74
adapted to receive a reel drive shaft (not shown) of a device into which the cassette is to be loaded. The inner cylindrical part
74
has a hollow
79
formed open at the bottom and extending short of the top of the part, so that the driving shaft of the recording-reproducing device can enter the inner cylindrical part
74
to drive the tape reel
55
. The inner cylindrical part
74
has a plurality of inward projections
77
adapted to mesh with the driving shaft. Each of the projections
77
has a groove
75
formed on the back side to reduce its thickness. The back grooves
75
must be limited in size lest they should cause inward deformation of the inner cylindrical part
74
under pressure from the tape wound thereon, which would decrease the diameter of the center hollow and hamper the insertion of the driving shaft from the recording-reproducing device. The outer cylindrical part
71
and the inner cylindrical part
74
are secured together with a plurality of connecting ribs
78
.
If the inner cylindrical part
74
, its inward projections
77
and side walls
76
were thus made as thin as possible while avoiding substantially unfavorable effect upon their strength, it would lead to uniform cooling of the resin after molding, reduction of molding strains, and shortening of the molding cycle.
However, the prior art technique described above is still unable to realize the shortening of the molding cycle satisfactorily. With the conventional design the inner ends of the projections
77
have to be thicker than the rest of the inner cylindrical part to cope with the speedup of the molding cycle. This naturally increases molding shrinkage which tends to cause malformation of the inner cylindrical part, but the problem has not been completely settled yet. If the inner cylindrical part is made as thin as the remainder by increasing the depth of the back grooves, there will be the danger of the bore of the inner cylindrical part
74
being deformed under the pressure, transmitted through the connecting ribs
78
, of the tape when the cassette has been stored for long with the tape wound thickly on the particular inner cylindrical part. This is particularly true with an inner cylindrical part of a cassette left inserted in a recording-reproducing device whose internal temperature is higher than the ambient temperature at which the cassette is ordinarily stored. Once the inner cylindrical part has been deformed to such an extent that it does not receive the driving shaft of the device when the cassette is loaded into the device, recording or reproducing will no longer be possible.
In view of these, the present invention aims at providing a tape reel equipped with means to prevent the deformation of the inner cylindrical part when it is made up of walls of the same thickness and thereby accelerating the molding cycle and reducing the molding strains of tape reels.
BRIEF SUMMARY OF THE INVENTION
The invention settles the prior art problems by means of:
(1) thickness-reducing grooves formed axially at the back of the ribs of the inner cylindrical part to allow the inner cylindrical part and walls that constitute its projections to have the same (constant) thickness throughout;
(2) extensions from both shoulder portions of connecting ribs formed on the inner cylindrical part toward the outer cylindrical part; and
(3) separating the outer and inner cylindrical parts of each reel hub by dispensing with ribs connecting the two parts.
Thus the invention provides a tape reel for a tape cassette wherein a pair of such reels are contained, comprising an upper flange and a hub which consists of a drum formed integrally with (formed in one piece with, or solidly joined to) a lower flange, said drum comprising an outer cylindrical part on which a tape is wound and an inner cylindrical part which permits the insertion of a driving shaft of a recording-reproducing device for the tape cassette, characterized in that the inner cylindrical part has projections adapted to engage with the driving shaft, each said projection having a groove formed on the back side for thickness reduction, and the inner cylindrical part and inner ends and both side walls of said projections all have the same thickness.
Such an inner cylindrical part having the same thin wall throughout has not been realized by the prior art. According to the present invention, a plurality of connecting ribs are provided joining the outer and inner cylindrical parts of the drum, and extensions are formed outwardly on the inner cylindrical part, on both shoulder portions close to each said connecting rib.
As alternative means, under the invention, a plurality of ribs are formed along the inner circumference of the outer cylindrical part, extending from the outer cylindrical part toward, but short of, the inner cylindrical part.
The invention thus provides a tape reel for a tape cassette characterized in that the inner cylindrical part of its hub drum has projections adapted to engage with the driving shaft of a recording-reproducing device, each said projection having a groove formed on the back side for thickness reduction, and the inner cylindrical part and inner ends and both side walls of said projections all have the same thickness. The structure prevents molding strains and permits shortening of the molding cycle. The prior art has not realized such an inner cylindrical part having the same thin wall throughout.
Under the invention, a plurality of connecting ribs are provided joining the outer and inner cylindrical parts of the drum, and extensions are formed outwardly on the inner cylindrical part, on both shoulder portions close to each said connecting rib. These extensions bear up under the pressure that a roll of tape applies to the inner cylindrical part and protect the part against deformation.
The invention alternatively provides a plurality of ribs formed along the inner circumference of the outer cylindrical part, extending from the outer cylindrical part toward, but short of, the inner cylindrical part. The ribs reinforce the outer cylindrical part and enhances the independence of the inner cylindrical part, with the result that the pressure of the tape wound up on it is taken up by the outer cylindrical part and the inner cylindrical part is protected against deformation.
REFERENCES:
patent: 4262856 (1981-04-01), Nakagawa
patent: 4371123 (1983-02-01), Watanabe
patent: 4511099 (1985-04-01), Nunokawa et al.
patent: 4605511 (1986-08-01), Machida
patent: 4664328 (1987-05-01), Yamada
patent: 4760972 (1988-08-01), Sasaki et al.
patent: 4807826 (1989-02-01), Iwahashi
patent: 4923137 (1990-05-01), Jorgensen et al.
patent: 5039024 (1991-08-01), Taniguchi
patent: 5252369 (1993-10-01), Akao et al.
patent: 5257749 (1993-11-01), Liepold et al.
patent: 5472150 (1995-12-01), Teuber et al.
patent: 5873543 (1999-02-01), Schneider et al.
patent: 2 040 264 (1980-08-01), None
patent: 4-228160 (1992-08-01), None
Hashizume Kenji
Kaneda Hiroshi
Okamura Masatoshi
Sato Shin'ichi
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